ASTM A788/A788M-23

Standard Specification for Steel Forgings, General Requirements

ABSTRACT
This specification covers a group of common requirements that, unless covered by the individual product specification in another ASTM document, applies to steel forgings for general use. Materials shall be produced primarily by either electric-furnace, basic oxygen, vacuum-induction (VIM), or open-hearth melting process. The primary melting may incorporate separate degassing or refining and may be followed by secondary melting, using electro slag (ESR) or vacuum arc remelting (VAR). Steel shall be forged by any of these three classes based on forging temperature: cold-worked forging, hot-cold-worked forging, or hot-worked forging. After forging, specimens shall be allowed to cool prior to reheating for heat treatment. Details of heat and product analyses for the evaluation of chemical composition are thoroughly discussed. Tension and hardness tests shall be conducted to evaluate mechanical properties such as percentage of elongation and reduction of area. Repair welding shall not be allowed unless permitted by the product specification.
SCOPE
1.1 This specification2 covers a group of common requirements that, unless otherwise specified in the individual product specification, shall apply to steel forgings under any of the following specifications issued by ASTM:    
ASTM Designation  
Title  
A266/A266M  
Carbon Steel Forgings for Pressure Vessel Components  
A288  
Carbon and Alloy Steel Forgings for Magnetic Retaining Rings for Turbine Generators    
A289/A289M  
Alloy Steel Forgings for Nonmagnetic Retaining Rings for Generators  
A290/A290M  
Carbon and Alloy Steel Forgings for Rings for Reduction Gears  
A291/A291M  
Steel Forgings, Carbon and Alloy, for Pinions, Gears, and Shafts for Reduction Gears    
A336/A336M  
Alloy Steel Forgings for Pressure and High-Temperature Parts    
A372/A372M  
Carbon and Alloy Steel Forgings for Thin-Walled Pressure Vessels    
A469/A469M  
Vacuum-Treated Steel Forgings for Generator Rotors  
A470/A470M  
Vacuum-Treated Carbon and Alloy Steel Forgings for Turbine Rotors and Shafts    
A471/A471M  
Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels    
A473  
Stainless Steel Forgings  
A504/A504M  
Wrought Carbon Steel Wheels  
A508/A508M  
Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels  
A541/A541M  
Quenched and Tempered Carbon and Alloy Steel Forgings for Pressure Vessel Components  
A579/A579M  
Superstrength Alloy Steel Forgings  
A592/A592M  
High-Strength Quenched and Tempered Low-Alloy Steel Forged Parts for Pressure Vessels  
A646/A646M  
Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings  
A649/A649M  
Forged Steel Rolls Used for Corrugating Paper Machinery    
A668/A668M  
Steel Forgings, Carbon and Alloy, for General Industrial Use  
A705/A705M  
Age-Hardening Stainless Steel Forgings  
A711/A711M  
Steel Forging Stock  
A723/A723M  
Alloy Steel Forgings for High-Strength Pressure Component Application  
A729/A729M  
Carbon and Alloy Steel Axles, Heat Treated, for Mass Transit and Electric Railway Service  
A765/A765M  
Carbon Steel and Low-Alloy Steel Pressure-Vessel-Component Forgings with Mandatory Toughness Requirements  
A837/A837M  
Steel Forgings, Alloy, for Carburizing Applications  
A859/A859M  
Age-Hardening Alloy Steel Forgings for Pressure Vessel Components  
A891/A891M  
Precipitation Hardening Iron Base Superalloy Forgings for Turbine Rotor Disks and Wheels    
A909/A909M  
Steel Forgings, Microalloy, for General Industrial Use  
A965/A965M  
Steel Forgings, Austenitic, for Pressure and High Temperature Parts  
A982/A982M  
Steel Forgings, Stainless, for Compressor and Turbine Airfoils  
A983/A983M  
Continuous Grain Flow Forged Carbon and Alloy Steel Crankshafts for Medium Speed Diesel Engines  
A986/A986M  
Magnetic Particle Examination of Cont...

General Information

• Status: Published
• Publication Date: 31-Aug-2023
• ICS: 77.140.85 - Iron and steel forgings
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

Relations

• Refers: ASTM E23-24 - Standard Test Methods for Notched Bar Impact Testing of Metallic Materials
• Effective Date: 01-Apr-2024
• Refers: ASTM A471/A471M-19(2024) - Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
• Effective Date: 01-Mar-2024
• Refers: ASTM A370-24 - Standard Test Methods and Definitions for Mechanical Testing of Steel Products
• Effective Date: 01-Mar-2024
• Refers: ASTM A1090/A1090M-19(2024) - Standard Specification for Forged Rings and Hollows for Use as Base Plates in Power Transmission Structures
• Effective Date: 01-Mar-2024
• Refers: ASTM A941-24 - Standard Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
• Effective Date: 01-Mar-2024
• Refers: ASTM E1316-24 - Standard Terminology for <?Pub Dtl?>Nondestructive Examinations
• Effective Date: 01-Feb-2024
• Refers: ASTM A859/A859M-23 - Standard Specification for Age-Hardening Alloy Steel Forgings for Pressure Vessel Components
• Effective Date: 01-Nov-2023
• Refers: ASTM A965/A965M-23 - Standard Specification for Steel Forgings, Austenitic, for Pressure and High Temperature Parts
• Effective Date: 01-Nov-2023
• Refers: ASTM A275/A275M-23 - Standard Practice for Magnetic Particle Examination of Steel Forgings
• Effective Date: 01-Nov-2023
• Refers: ASTM A388/A388M-23 - Standard Practice for Ultrasonic Examination of Steel Forgings
• Effective Date: 01-Nov-2023
• Refers: ASTM A336/A336M-23 - Standard Specification for Alloy Steel Forgings for Pressure and High-Temperature Parts
• Effective Date: 01-Nov-2023
• Refers: ASTM A508/A508M-23a - Standard Specification for Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels
• Effective Date: 01-Nov-2023
• Refers: ASTM A508/A508M-23 - Standard Specification for Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels
• Effective Date: 01-Sep-2023
• Refers: ASTM A1021/A1021M-20 - Standard Specification for Martensitic Stainless Steel Forgings and Forging Stock for High-Temperature Service
• Effective Date: 01-May-2020
• Refers: ASTM A982/A982M-10(2020) - Standard Specification for Steel Forgings, Stainless, for Compressor and Turbine Airfoils
• Effective Date: 01-Mar-2020

Overview

ASTM A788/A788M-23 - Standard Specification for Steel Forgings, General Requirements establishes a set of common requirements for steel forgings intended for general use. Developed by ASTM International, this standard applies unless an individual ASTM product specification defines alternative or additional criteria. ASTM A788/A788M-23 ensures uniformity in the production, analysis, and testing of steel forgings, covering processes such as electric-furnace, basic oxygen, vacuum-induction, and open-hearth melting. The specification also addresses forging processes, heat treatment, and mechanical property verification, creating a foundational quality benchmark for a variety of steel forgings used across multiple industries.

Key Topics

• Scope of Requirements: Outlines baseline requirements applicable to a broad range of steel forgings, unless overridden by individual product standards. This standard applies to numerous related ASTM specifications for products like pressure vessels, turbine components, axles, and wheels.
• Melting and Refining Processes: Describes permissible primary steelmaking methods, including electric-furnace, basic oxygen, vacuum-induction, and open-hearth, with possible secondary melting such as electro slag remelting (ESR) or vacuum arc remelting (VAR).
• Forging Methods: Accepts steel forgings produced using cold-worked, hot-cold-worked, or hot-worked processes, depending on the required application and subsequent heat treatment.
• Chemical Composition: Details necessary analyses for verifying and controlling the chemical makeup as defined in each product specification. Both heat and product analyses are outlined to maintain composition consistency.
• Mechanical Testing: Specifies the requirement for tension and hardness tests to verify essential mechanical properties, such as elongation and reduction of area.
• Heat Treatment: Establishes guidelines for cooling post-forging and reheating for consistent material properties.
• Restrictions on Repair Welding: States that repair welding is not permitted unless explicitly allowed by the applicable product standard.
• Ordering and Certification: Provides direction for purchasers to specify required details and for producers to include certification information in compliance with the standard.

Applications

The ASTM A788/A788M-23 standard is widely used across industries that require reliable steel forgings with predictable mechanical and chemical properties. Some of the primary application areas include:

• Pressure Vessels: Common in oil and gas, chemical processing, and power generation sectors.
• Turbine Generators and Rotors: Essential for energy and aerospace industries, ensuring component durability and safety.
• Gears, Pinions, and Shafts: Used in heavy machinery, industrial equipment, and reduction gears.
• Rail and Transportation: Applies to forged axles, wheels, and related components for rail and transit systems.
• Aerospace and Defense: Critical for parts requiring stringent metallurgical consistency and traceability, such as those used in aircraft engines and structures.
• General Industrial Use: Suitable for any industrial purpose where forged steel parts are needed and where specific product standards refer back to ASTM A788/A788M.

Ensuring compliance with ASTM A788/A788M-23 helps manufacturers and purchasers achieve higher consistency and reliability in steel forgings, creating safer, longer-lasting products across various industries.

Related Standards

Many individual product specifications reference or rely upon ASTM A788/A788M-23 for their general requirements. Notable related standards include:

• ASTM A266/A266M: Carbon Steel Forgings for Pressure Vessel Components
• ASTM A336/A336M: Alloy Steel Forgings for Pressure and High-Temperature Parts
• ASTM A508/A508M: Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels
• ASTM A668/A668M: Steel Forgings, Carbon and Alloy, for General Industrial Use
• ASTM A473: Stainless Steel Forgings
• ASTM A705/A705M: Age-Hardening Stainless Steel Forgings
• ASME Boiler and Pressure Vessel Code (Section II): Referenced for critical applications

For a complete list of all referring standards and test methods, consult relevant ASTM documentation or the full scope of ASTM A788/A788M-23.

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Keywords: ASTM A788, steel forgings standard, general forging requirements, mechanical testing, chemical analysis, steel forging applications, ASTM steel standards, pressure vessel forgings, turbine component forgings, industrial steel forgings.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: A788/A788M − 23
Standard Specification for
Steel Forgings, General Requirements
This standard is issued under the fixed designation A788/A788M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
A668/A668M Steel Forgings, Carbon and Alloy, for General
Industrial Use
1.1 This specification covers a group of common require-
A705/A705M Age-Hardening Stainless Steel Forgings
ments that, unless otherwise specified in the individual product A711/A711M Steel Forging Stock
A723/A723M Alloy Steel Forgings for High-Strength Pres-
specification, shall apply to steel forgings under any of the
sure Component Application
following specifications issued by ASTM:
A729/A729M Carbon and Alloy Steel Axles, Heat Treated,
for Mass Transit and Electric Railway Ser-
ASTM Designation Title
vice
A765/A765M Carbon Steel and Low-Alloy Steel Pressure-
A266/A266M Carbon Steel Forgings for Pressure Vessel
Vessel-Component Forgings with Manda-
Components
tory Toughness Requirements
A288 Carbon and Alloy Steel Forgings for Magnetic
A837/A837M Steel Forgings, Alloy, for Carburizing Applica-
Retaining Rings for Turbine Generators
tions
A289/A289M Alloy Steel Forgings for Nonmagnetic Retain-
A859/A859M Age-Hardening Alloy Steel Forgings for Pres-
ing Rings for Generators
sure Vessel Components
A290/A290M Carbon and Alloy Steel Forgings for Rings for
A891/A891M Precipitation Hardening Iron Base Superalloy
Reduction Gears
Forgings for Turbine Rotor Disks and
A291/A291M Steel Forgings, Carbon and Alloy, for Pinions,
Wheels
Gears, and Shafts for Reduction Gears
A909/A909M Steel Forgings, Microalloy, for General Indus-
A336/A336M Alloy Steel Forgings for Pressure and High-
trial Use
Temperature Parts
A965/A965M Steel Forgings, Austenitic, for Pressure and
A372/A372M Carbon and Alloy Steel Forgings for Thin-
High Temperature Parts
Walled Pressure Vessels
A982/A982M Steel Forgings, Stainless, for Compressor
A469/A469M Vacuum-Treated Steel Forgings for Generator
and Turbine Airfoils
Rotors
A983/A983M Continuous Grain Flow Forged Carbon and
A470/A470M Vacuum-Treated Carbon and Alloy Steel
Alloy Steel Crankshafts for Medium Speed
Forgings for Turbine Rotors and Shafts
Diesel Engines
A471/A471M Vacuum-Treated Alloy Steel Forgings for Tur-
A986/A986M Magnetic Particle Examination of Continuous
bine Rotor Disks and Wheels
Grain Flow Crankshaft Forgings
A473 Stainless Steel Forgings
A1021/A1021M Martensitic Stainless Steel Forgings and
A504/A504M Wrought Carbon Steel Wheels
Forging Stock for High-Temperature Ser-
A508/A508M Quenched and Tempered Vacuum-Treated
vice
Carbon and Alloy Steel Forgings for Pres-
A1049/A1049M Stainless Steel Forgings, Ferritic/Austenitic
sure Vessels
(Duplex), for Pressure Vessels and Related
A541/A541M Quenched and Tempered Carbon and Alloy
Components
Steel Forgings for Pressure Vessel Compo-
A1090/A1090M Forged Rings and Hollows for Use as Base
nents
Plates in Power Transmission Structures
A579/A579M Superstrength Alloy Steel Forgings
A592/A592M High-Strength Quenched and Tempered Low-
1.2 In case of conflict in requirements, the requirements of
Alloy Steel Forged Parts for Pressure Ves-
the individual product specifications shall prevail over those of
sels
A646/A646M Premium Quality Alloy Steel Blooms and Bil-
this specification.
lets for Aircraft and Aerospace Forgings
A649/A649M Forged Steel Rolls Used for Corrugating Pa-
1.3 The purchaser may specify additional requirements (see
per Machinery
4.2.3) that do not negate any of the provisions of either this
specification or of the individual product specifications. The
acceptance of any such additional requirements shall be
This specification is under the jurisdiction of ASTM Committee A01 on Steel, dependent on negotiations with the supplier and must be
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
included in the order.
A01.06 on Steel Forgings and Billets.
Current edition approved Sept. 1, 2023. Published September 2023. Originally
1.4 If, by agreement, forgings are to be supplied in a
approved in 1984. Last previous edition approved in 2022 as A788/A788M – 22a.
partially completed condition, that is, all of the provisions of
DOI: 10.1520/A0788_A0788M-23.
the product specification have not been filled, then the material
For ASME Boiler and Pressure Vessel Code applications, see related Specifi-
cation SA–788 in Section II of that code. marking (see Section 17) and certification (see Section 16)
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A788/A788M − 23
shall reflect the extent to which the product specification A469/A469M Specification for Vacuum-Treated Steel Forg-
requirements have been met. ings for Generator Rotors
A470/A470M Specification for Vacuum-Treated Carbon and
1.5 As noted in the Certification Section (16), the number
Alloy Steel Forgings for Turbine Rotors and Shafts
and year date of this specification, as well as that of the product
A471/A471M Specification for Vacuum-Treated Alloy Steel
specification, are required to be included in the product
Forgings for Turbine Rotor Disks and Wheels
certification.
A473 Specification for Stainless Steel Forgings
1.6 When the SI version of a product specification is
A504/A504M Specification for Wrought Carbon Steel
required by the purchase order, Specification A788/A788M
Wheels
shall be used in conjunction with Test Methods A1058 instead
A508/A508M Specification for Quenched and Tempered
of Test Methods and Definitions A370.
Vacuum-Treated Carbon and Alloy Steel Forgings for
1.7 The values stated in either SI units or inch-pound units
Pressure Vessels
are to be regarded separately as standard. The values stated in
A541/A541M Specification for Quenched and Tempered
each system are not necessarily exact equivalents; therefore, to
Carbon and Alloy Steel Forgings for Pressure Vessel
ensure conformance with the standard, each system shall be
Components
used independently of the other and values from the two
A551/A551M Specification for Carbon Steel Tires for Rail-
systems shall not be combined.
way and Rapid Transit Applications
1.8 This standard does not purport to address all of the
A579/A579M Specification for Superstrength Alloy Steel
safety concerns, if any, associated with its use. It is the
Forgings
responsibility of the user of this standard to establish appro-
A592/A592M Specification for High-Strength Quenched
priate safety, health, and environmental practices and deter-
and Tempered Low-Alloy Steel Forged Parts for Pressure
mine the applicability of regulatory limitations prior to use.
Vessels
1.9 This international standard was developed in accor-
A646/A646M Specification for Premium Quality Alloy Steel
dance with internationally recognized principles on standard-
Blooms and Billets for Aircraft and Aerospace Forgings
ization established in the Decision on Principles for the
A649/A649M Specification for Forged Steel Rolls Used for
Development of International Standards, Guides and Recom-
Corrugating Paper Machinery
mendations issued by the World Trade Organization Technical
A668/A668M Specification for Steel Forgings, Carbon and
Barriers to Trade (TBT) Committee.
Alloy, for General Industrial Use
A705/A705M Specification for Age-Hardening Stainless
2. Referenced Documents
3 Steel Forgings
2.1 ASTM Standards:
A711/A711M Specification for Steel Forging Stock
A266/A266M Specification for Carbon Steel Forgings for
A723/A723M Specification for Alloy Steel Forgings for
Pressure Vessel Components
High-Strength Pressure Component Application
A275/A275M Practice for Magnetic Particle Examination of
A729/A729M Specification for Carbon and Alloy Steel
Steel Forgings
Axles, Heat-Treated, for Mass Transit and Electric Rail-
A288 Specification for Carbon and Alloy Steel Forgings for
way Service
Magnetic Retaining Rings for Turbine Generators
A751 Test Methods and Practices for Chemical Analysis of
A289/A289M Specification for Alloy Steel Forgings for
Steel Products
Nonmagnetic Retaining Rings for Generators (Withdrawn
A765/A765M Specification for Carbon Steel and Low-Alloy
2023)
Steel Pressure-Vessel-Component Forgings with Manda-
A290/A290M Specification for Carbon and Alloy Steel
Forgings for Rings for Reduction Gears tory Toughness Requirements
A291/A291M Specification for Steel Forgings, Carbon and A833 Test Method for Indentation Hardness of Metallic
Alloy, for Pinions, Gears and Shafts for Reduction Gears
Materials by Comparison Hardness Testers
A336/A336M Specification for Alloy Steel Forgings for
A837/A837M Specification for Steel Forgings, Alloy, for
Pressure and High-Temperature Parts
Carburizing Applications
A370 Test Methods and Definitions for Mechanical Testing
A859/A859M Specification for Age-Hardening Alloy Steel
of Steel Products
Forgings for Pressure Vessel Components
A372/A372M Specification for Carbon and Alloy Steel
A891/A891M Specification for Precipitation Hardening Iron
Forgings for Thin-Walled Pressure Vessels
Base Superalloy Forgings for Turbine Rotor Disks and
A388/A388M Practice for Ultrasonic Examination of Steel
Wheels
Forgings
A909/A909M Specification for Steel Forgings, Microalloy,
for General Industrial Use
A939/A939M Practice for Ultrasonic Examination from
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Bored Surfaces of Cylindrical Forgings (Withdrawn
Standards volume information, refer to the standard’s Document Summary page on
2021)
the ASTM website.
4 A941 Terminology Relating to Steel, Stainless Steel, Related
The last approved version of this historical standard is referenced on
www.astm.org. Alloys, and Ferroalloys
A788/A788M − 23
A965/A965M Specification for Steel Forgings, Austenitic, 3.1.1 A941 Terminology Relating to Steel, Stainless Steel,
for Pressure and High Temperature Parts Related Alloys, and Ferroalloys
A966/A966M Practice for Magnetic Particle Examination of 3.1.2 A370 Test Methods and Definitions for Mechanical
Steel Forgings Using Alternating Current Testing of Steel Products
A982/A982M Specification for Steel Forgings, Stainless, for 3.1.3 A751 Test Methods and Practices for Chemical Analy-
Compressor and Turbine Airfoils sis of Steel Products
A983/A983M Specification for Continuous Grain Flow 3.1.4 E1316 Terminology for Nondestructive Examinations
Forged Carbon and Alloy Steel Crankshafts for Medium
3.2 Forging Definitions:
Speed Diesel Engines
3.2.1 steel forging, n—the product of a substantially com-
A986/A986M Specification for Magnetic Particle Examina-
pressive plastic working operation that consolidates the mate-
tion of Continuous Grain Flow Crankshaft Forgings
rial and produces the desired shape. The plastic working may
A991/A991M Test Method for Conducting Temperature
be performed by a hammer, press, forging machine, or ring
Uniformity Surveys of Furnaces Used to Heat Treat Steel
rolling machine, and must deform the material to produce an
Products
essentially wrought structure.
A1021/A1021M Specification for Martensitic Stainless Steel
3.2.1.1 Discussion—Hot rolling operations may be used to
Forgings and Forging Stock for High-Temperature Service
produce blooms or billets for reforging.
A1049/A1049M Specification for Stainless Steel Forgings,
3.3 Forging Geometries:
Ferritic/Austenitic (Duplex), for Pressure Vessels and
3.3.1 bar forging, n—forging that has no bore and having an
Related Components
axial length greater than its maximum cross sectional dimen-
A1058 Test Methods for Mechanical Testing of Steel
sion.
Products—Metric
3.3.1.1 Discussion—More than one cross sectional shape or
A1090/A1090M Specification for Forged Rings and Hol-
size may be included. Sometimes referred to as a solid forging.
lows for Use as Base Plates in Power Transmission
Structures 3.3.2 disk forging, n—forging, sometimes referred to as a
E23 Test Methods for Notched Bar Impact Testing of Me- pancake forging, that has (a) an axial length appreciably less
tallic Materials than its diameter, (b) may be dished on one or both faces, and
E112 Test Methods for Determining Average Grain Size (c) final forging includes upsetting operations to reduce the
E165/E165M Practice for Liquid Penetrant Testing for Gen- height of the stock and increase its diameter.
eral Industry 3.3.2.1 Discussion—Since much of the hot working is done
E380 Practice for Use of the International System of Units in axially compressing the stock, the central area may not
(SI) (the Modernized Metric System) (Withdrawn 1997) receive sufficient consolidation. To counter this effect, consid-
E399 Test Method for Linear-Elastic Plane-Strain Fracture eration is usually given to the initial saddening (see 3.3.6) of
Toughness of Metallic Materials the ingot or billet.
E428 Practice for Fabrication and Control of Metal, Other
3.3.3 hollow forging, n—forging (also known as a shell
than Aluminum, Reference Blocks Used in Ultrasonic
forging or a mandrel forging) in which (a) the axial length is
Testing (Withdrawn 2019)
equal to or greater than the diameter, and (b) the forging length
E1290 Test Method for Crack-Tip Opening Displacement
and wall thickness are produced by hot working over a mandrel
(CTOD) Fracture Toughness Measurement (Withdrawn
(usually water cooled) such that the bore diameter remains
2013)
essentially the same as that of the mandrel.
E1316 Terminology for Nondestructive Examinations
3.3.3.1 Discussion—Unless a hollow ingot has been used,
E1820 Test Method for Measurement of Fracture Toughness
the starting slug is hot trepanned or punched after upsetting and
E1916 Guide for Identification of Mixed Lots of Metals
the bore diameter adjusted to suit the forging mandrel. The
2.2 Other Standards:
outside diameter may be contoured if required. The workpiece
ANSI/ASME B46.1 Surface Texture (Surface Roughness,
is forged between the upper die and lower dies while the
Waviness and Lay)
mandrel is supported by cranes or manipulators to facilitate
ASME Boiler and Pressure Vessel Code
rotation.
SAE AMS 2750 Pyrometry
3.3.4 ring forging, n—type of hollow forging in which (a)
the axial length is less than the diameter, (b) the wall thickness
3. Terminology
is reduced, and (c) the outside diameter is increased by hot
3.1 Definitions of Terms—For definitions of terms used in
working between the top die and a mandrel supported on
this standard that are not included in 3.2 – 3.5, refer to the
temporary saddles.
following standards:
3.3.4.1 Discussion—Forging between the top die and the
mandrel enables the ring diameter to be increased while
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
reducing the wall thickness, without increasing the axial
4th Floor, New York, NY 10036, http://www.ansi.org.
length.
Available from American Society of Mechanical Engineers (ASME), ASME
International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
3.3.5 ring rolling, n—involves the use of specialized equip-
www.asme.org.
ment whereby a hot-punched, trepanned, or bored disk is (a)
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale,
PA 15096, http://www.sae.org. hot worked between a powered outer roller and an idling inner
A788/A788M − 23
roller, such that the wall thickness is reduced and the outside mold to form a continuous cast product with a change from
diameter is increased, and (b) the axial length of the ring is not heat to heat along its length (see 8.1.5).
intended to increase and may be contained by a radially
3.5.6 strand casting, n—steel from one heat poured into a
oriented tapered roller.
cooled open-ended mold to form a continuous strand or
3.3.6 saddening, n—term used in the open die forging strands.
industry to describe the initial hot working of an ingot for
3.5.7 vacuum carbon deoxidation (VCD), n—steelmaking
surface compaction and flute working surface prior to full
process in which primary deoxidation occurs during vacuum
working of the ingot cross section.
treatment as a result of the carbon-oxygen reaction. In order for
3.3.6.1 Discussion—The term is also extended to initial hot
primary deoxidation to occur during vacuum treatment, deoxi-
working intended to give consolidation of ingot central areas
dizing agents such as aluminum or silicon are not to be added
prior to upsetting when making products such as turbine and
to the melt in any significant amount prior to the vacuum
generator rotors and tube sheets.
treatment operation.
3.3.7 slab forging, n—forging, sometimes referred to as a
forged plate, that is usually square or rectangular in shape, with 4. Ordering Information
a thickness appreciably smaller than the other dimension. The
4.1 It shall be the responsibility of the purchaser to specify
hot working may include upsetting.
all requirements that are necessary for forgings under the
applicable product specification. Such requirements to be
3.4 billets and blooms, n—interchangeable terms represent-
considered include, but are not restricted to, the following:
ing hot-worked semi-finished product intended as a starting
stock for making forgings. 4.1.1 Quantity,
4.1.2 Dimensions, including tolerances and surface finishes.
3.4.1 Discussion—No size limitations are assumed for ei-
4.1.3 Specification number with type, class, and grade as
ther term. Cast shapes produced by a continuous casting
process, without subsequent work, are considered to be ingots applicable (including year date), and should include:
4.1.3.1 Number of copies of the material test report.
for the purposes of this specification, and if supplied as billets
or blooms must carry the descriptor Cast Billet or Cast Bloom. 4.1.3.2 Choice of testing track from the options listed in Test
Methods A1058 when forgings are ordered to a suffix M
3.5 Definitions of Terms Specific to This Standard:
product standard. If the choice of test track is not made in the
3.5.1 bottom pouring, n—steel from a single heat, or from a
ordering information then the default ASTM track shall be used
multiple heat tapped into a common ladle (see 8.1.1 and 8.1.2),
as noted in Test Methods A1058.
introduced into ingot mold(s) such that they are filled from the
bottom up. One or more molds can be set up on an individual 4.2 Additional information including the following may be
added by agreement with the supplier:
plate, and more than one plate may be poured in sequence from
a heat. 4.2.1 Type of heat treatment when alternative methods are
allowed by the product specification,
3.5.2 ingot, n—the product obtained when molten steel,
4.2.2 Supplementary requirements, if any, and
upon being cast into a mold, is subsequently capable of being
4.2.3 Additional requirements (see 1.4, 16.1.6, 16.1.7, and
wrought to produce forgings. Bottom poured, top poured, or
16.1.9).
remelted ingots as well as continuous strand cast product are
4.2.4 Repair welding NOT permitted.
included in this definition.
4.3 For dual format specifications, unless otherwise
3.5.3 intercritical heat treatment, n—use of a multi-stage
specified, the inch-pound units shall be used.
heat treatment procedure in which the material is first austen-
itized at a temperature above the upper critical temperature
5. Melting Process
(Ac3) followed by cooling below the lower critical temperature
(Ac1). The material is then reheated to a temperature in the
5.1 Unless otherwise specified in the product specification,
intercritical range between the Ac1 and the Ac3 and again
the steel shall be produced by any of the following primary
cooled below the Ac1, followed by subcritical tempering in the
processes: electric-furnace (EF), basic oxygen (BOF), or
range specified in the material specification.
vacuum-induction (VIM). The primary melting may incorpo-
3.5.3.1 Discussion—This procedure is generally applicable
rate separate degassing or refining and may be followed by
to low hardenability carbon and low alloy steels that would
secondary processes such as, but not limited to, argon-oxygen
usually have a microstructure of ferrite and pearlite in the heat
decarburization (AOD), vacuum-oxygen decarburization
treated section size of the component being heat treated.
(VOD), or vacuum degassing (VD). The steel may additionally
undergo electro slag remelting (ESR) or vacuum arc remelting
3.5.4 precipitation deoxidation, n—steelmaking process in
(VAR).
which primary deoxidation is achieved by the addition of
5.1.1 The steel shall be fully killed.
strong deoxidizing agents, such as aluminum, early in the
process, and holding the steel in the molten state for sufficient
5.2 The molten steel may be vacuum-treated prior to or
time for the products of deoxidation to separate from the melt
during pouring of the ingot.
to the slag.
5.2.1 When vacuum treatment of the molten steel is re-
3.5.5 sequential or continuous strand casting, n—steel from quired by the product specification the following conditions
several heats poured consecutively into a cooled open-ended shall apply:
A788/A788M − 23
5.2.1.1 When the vacuum stream degassing process is used, 8.1.3 For multiple-heat ingots, either individual heat analy-
the vacuum system must be of sufficient capacity to effect a ses or a weighted average (see Annex A2) may be taken. The
blank-off pressure low enough (usually less than 1000 μm) to results of the method used shall conform to the requirements of
break up the normal tight, rope-like stream of molten metal the product specification.
into a wide-angled conical stream of relatively small droplets.
8.1.4 With the exception of the product from multiple heats
The capacity of the system must also be sufficiently high to sequentially cast in strand casting machines (see 8.1.5), if the
reduce the initial surge pressure at the start of the pour to a low
test sample taken for a heat analysis is lost or declared
level within 2 min. inadequate for chemical determinations, the steel producer may
5.2.1.2 When the vacuum-lift process is utilized, the molten
take alternative samples from appropriate locations near the
metal shall be repeatedly drawn into the evacuated vessel to surface of the ingot or forging as necessary to establish the
give a recirculation factor (see Annex A1) of at least 2.5 to
analysis of the heat in question.
ensure thorough degassing and mixing of the entire heat. The
8.1.5 For multiple heats sequentially cast in strand casting
evacuation system shall be capable of reducing the pressure
machines, the heat analysis shall be determined for each
surges, which occur each time a new portion of steel is
individual heat in accordance with 8.1.1 or 8.1.2 if applicable.
admitted to the vessel to increasingly lower levels, until a
8.1.5.1 If, for multiple heats sequentially strand cast, the test
blank-off pressure (usually less than 1000 μm) is achieved
sample is lost or declared inadequate for chemical analysis
signifying the end of the degassing treatment.
determination, alternative samples, remote from the transition
5.2.1.3 When the ladle degassing process is used, the
zones, may be taken by the steel producer from the cast
evacuation system shall be capable of reducing the system
material or product of that heat, as defined in 8.2 or 8.3 as
vacuum pressure to a low level (usually less than 1000 μm).
appropriate.
The molten metal shall be adequately stirred for a sufficient
8.1.6 Heat Analysis for Remelted Ingots:
length of time to maximize exposure to the evacuated atmo-
8.1.6.1 When consumable remelting processes are used, a
sphere.
chemical analysis shall be taken from a remelted ingot (or the
5.2.1.4 Other methods of vacuum treatment may be used if
product of a remelted ingot) for the remelt heat analysis.
the supplier can demonstrate adequate degassing and accept-
8.1.6.2 When more than one electrode is prepared from a
able properties in the finished forging to the satisfaction of the
master or parent heat for remelting in the same facility by the
purchaser.
same process, then the heat analysis obtained from one
remelted ingot, or the product from that ingot, shall be taken as
6. Forging
the heat analysis for all of the remelted ingots from that master
6.1 Forgings shall be made in accordance with 3.2.1.
heat. For analysis from each remelted ingot, see Supplementary
Requirement S27.
6.2 Because of differences in manufacture, hot-rolled, or
8.1.6.3 When electrodes from different master heats are
hot-rolled and cold-finished bars (semi-finished or finished),
remelted sequentially, an analysis shall be made in each zone
billets, or blooms are not considered to be forgings.
of the remelted ingot corresponding to at least one electrode
6.3 Cold worked forgings shall be made from material
from each master heat. The resultant chemical analysis of each
previously hot worked by forging or rolling; however, a
zone shall conform to the requirements of the product specifi-
hot-cold worked forging may be produced in one continuous
cation. The heat analysis of the remelted ingot shall be
operation wherein the material is first hot worked and then cold
represented by a weighted average (see Annex A2) of the
worked by control of the finishing temperature.
individual chemical analyses for each zone.
8.1.6.4 Limits on aluminum content in remelt ingots shall be
7. Cooling Prior to Heat Treatment
set as required in the product specification.
7.1 After forging and before reheating for heat treatment,
8.2 Heat Number Assignment for Sequentially Strand Cast
the forgings shall be allowed to cool in such a manner as to
Material—When heats of the same chemical composition are
prevent injury and, in the case of ferritic forgings, to permit
sequentially strand cast, the heat number assigned to the cast
substantially complete transformation of austenite.
product may remain unchanged until all of the steel in the
product is from the following heat, except when Supplemen-
8. Chemical Composition
tary Requirement S3 is invoked.
8.1 Heat Analysis:
8.3 Identification of Material of Different Chemical Compo-
8.1.1 An analysis of each heat of steel shall be made by the
sition Ranges, Sequentially Strand Cast—Because of intermix-
steel producer to determine the percentages of those elements
ing in the tun dish, separation and identification of the resultant
specified in the product specification. This analysis shall be
transition material is required when steels of different chemical
made from a test sample preferably taken during the pouring of
composition ranges are sequentially strand cast. The steel
the heat and shall conform to the requirements of the product
producer shall remove the transition material by any estab-
specification.
lished procedure that positively separates the grades.
8.1.2 When multiple heats are tapped into a common ladle,
8.4 Product Analysis:
the ladle chemistry shall apply. The chemical composition thus
determined shall conform to the requirements of the product 8.4.1 An analysis may be made by the purchaser from a
specification. forging representing each heat or multiple heat (see 8.1).
A788/A788M − 23
Samples for analysis may be taken from the forging or from a Methods and Definitions A370. When forgings are ordered to
full-size prolongation. The sampling location shall be at any SI requirements (M suffix standard) Test Methods A1058 shall
point from the midradius to the outer surface of disk or other be used (see 4.1.3.2).
solid forgings. For hollow or bored forgings, the sampling 10.1.1 In addition to the hardness testing provisions of Test
location shall be at any point from the midwall of the hollow Methods and Definitions A370 or, when required, Test Meth-
configuration to the outer surface. The analysis may also be ods A1058, comparison hardness testing in accordance with
taken from a mechanical test specimen or the mechanical test Test Method A833 may be used in determining the hardness of
location as defined in the product specification. forgings.
8.4.2 The chemical composition thus determined shall con- 10.1.2 It can be impractical to hardness test larger forgings
form to the heat analysis requirements of the forging specifi- by any other method than portable hardness testing. Product
standards that state a required hardness result of HBW or HRC
cation subject to the permissible variations specified in Table 1,
for those elements listed in the product specification. Limita- can have this value tested per the portable hardness testers in
Test Methods and Definitions A370. The hardness results must
tions on the application of the allowances in Table 1 may be
made in the product specification for specified elements. be presented and reported according to Test Methods and
Definitions A370, Portable Hardness Testing.
8.4.3 Limits on formula calculations involving elemental
10.1.3 Unless otherwise specified, the forging weight and
contents shall apply only to the heat analysis, unless agreed
upon between supplier and purchaser. Where limits on formula dimension (diameter, length, etc.) used for determining the
number and the location of mechanical properties refer to the
calculations involving elemental contents apply to product
weight and dimension at the time of heat treatment, excluding
analysis by such agreement, permissible variations in the
test prolongation(s). For forgings heat treated as a multiple
formula calculation results beyond the limits for the heat
forging, the weight and dimensions of the multiple forging
analysis shall also be agreed upon between supplier and
shall be used.
purchaser. Examples of such formula calculations include, but
are not limited to, the following:
10.2 Fracture Appearance Transition Temperature
carbon equivalent CE 5 (FATT )—For a product specification (including M suffix SI
n
specifications) that requires the determination of the fracture
C1 Mn/61 Cr 1 Mo 1 V ⁄51 Ni 1 Cu ⁄15
~ ! ~ !
appearance transition temperature (FATT ) where n is the
n
(1)
required minimum percentage of shear fracture as measured on
J factor 5 ~Mn 1 Si! × ~P 1 Sn! × 10 (2)
the fracture surface of a Charpy V-notch sample by one of the
requirements for specific elemental balance or sufficiency, methods described in Test Methods and Definitions A370, the
Charpy test specimen location and orientation shall be as
typically related to Ti, Nb, or Al and interstitials C and N,
specified in the product standard.
such as Nb 5 5 × C minimum. (3)
10.2.1 When the actual fracture appearance transition tem-
8.5 Residual and Unspecified Elements—Provisions for the
perature is required, break at least four specimens that have
limitation of certain residual and unspecified elements have
been taken from a comparable location. Test each specimen at
been made in Supplementary Requirements S1 and S2, respec-
a different temperature such that the percentage of shear
tively.
fracture will be both above and below the value of n, but within
a range of 60.60 times that of the specified value of n. It is
8.6 Grade substitution is not permitted.
desirable that two of the specimens will have values of
8.7 Method of Analysis—Methods included in Test Methods
cleavage fracture above the value of n, and two will have
and Practices A751 shall be used for referee purposes.
values below this level. Plot the percentage shear fracture
against test temperature and determine the transition tempera-
9. Heat Treatment
ture by interpolation (extrapolation is not permitted).
9.1 Heat treatment shall be performed as specified in the 10.2.2 When, rather than calling for an actual FATT as
n
product specification. Supplementary Requirement S4 con-
described in 10.2.1, the product specification requires a mini-
cerns a specialized heat treat process (see 3.5.3) whose mum FATT at a given temperature then, unless otherwise
n
application will be controlled in the product specification.
specified, a single test run at the required temperature satisfies
Unless otherwise specified during a heat treating hold cycle, the requirement provided that the fracture appearance value is
the recorded furnace temperature shall be within 625 °F
at least n. For example, a single test run at 100 °F [38 °C] with
[615 °C] of the controlling set point temperature. Material a fracture appearance of 55 % shear fracture satisfies a require-
shall be heat treated in the working zone of a furnace that has
ment of FATT at 100 °F [38 °C].
been surveyed in accordance with Test Method A991/A991M
10.3 Retests—If the results of the tests do not conform to the
or AMS 2750 provided that the working zone was established
requirements specified, retests are permitted as outlined in Test
using a variation of 625 °F [615 °C] or less from the furnace
Methods and Definitions A370 or as follows:
set point.
10.3.1 If the percentage of elongation or reduction of area of
any tension test specimen is less than specified because a flaw
10. Mechanical Testing
becomes evident in the test specimen during testing, a retest
10.1 Test Methods—Except as specified in 4.1.3.2 or 10.2.1 shall be allowed provided that the defect was not attributable to
and 10.2.2, all tests shall be conducted in accordance with Test ruptures, cracks, or flakes in the steel.
A788/A788M − 23
TABLE 1 Permissible Variations in Product Analysis for Killed Steel
NOTE 1—This table covers permissible variations in product analysis for most of the elements commonly found in killed steels under the jurisdiction
of A01.06. This table is applicable only for those elements for which product analysis variations are permitted by the material specification. The listed
variation value is subtracted from the minimum specified limit, or added to the maximum specified limit for the heat analysis in the product specification.
NOTE 2—Product cross-sectional area (taken at right angles to the axis of the original ingot or billet) is defined as either: (1) maximum cross-sectional
area of a bored forging excluding the bored region, (2) maximum cross-sectional area of the unmachined forging, or (3) maximum cross-sectional area
of the billet bloom or slab.
Permissible Variation Over the Specified Maximum Limit or Under the Specified Minimum Limit
2A 2 2 2 2
Element Maximum or Up to and Over 100 in. to Over 200 in. to Over 400 in. to Over 800 in. to Over 1600 in.
2 2 2 2
200 in. incl
Specified Range—I incl 100 in. 400 in. incl 800 in. incl 1600 in. incl [over 10 300
2 A [650 cm to 2 2 2 2
[650 cm ] [1300 cm to [2600 cm to [5200 cm to cm ]
1300 cm ]
2 2 2
2600 cm ] 5200 cm ] 10 300 cm ]
Carbon Up to and incl 0.05 0.005 0.005 0.005 0.01 0.01 0.01
0.06 to 0.10, incl 0.01 0.01 0.01 0.01 0.01 0.01
0.11 to 0.25, incl 0.02 0.03 0.03 0.04 0.05 0.05
0.26 to 0.55, incl 0.03 0.04 0.04 0.05 0.06 0.06
0.56 and over 0.04 0.05 0.05 0.06 0.07 0.07
Manganese Up to and incl 0.90 0.03 0.04 0.05 0.06 0.07 0.08
0.91 and over 0.06 0.06 0.07 0.08 0.08 0.09
Phosphorus Up to and incl 0.05 0.008 0.008 0.010 0.010 0.015 0.015
Sulfur Up to and incl 0.030 0.005 0.005 0.005 0.005 0.006 0.006
0.031 to 0.060 incl 0.008 0.010 0.010 0.010 0.015 0.015
Silicon Up to and incl 0.35 0.02 0.03 0.04 0.04 0.05 0.06
0.36 and over 0.05 0.06 0.06 0.07 0.07 0.08
Nickel Up to and incl 1.00 0.03 0.03 0.03 0.03 0.03 0.03
1.01 to 2.00, incl 0.05 0.05 0.05 0.05 0.05 0.05
2.01 to 5.30, incl 0.07 0.07 0.07 0.07 0.07 0.07
5.31 to 10.00, incl 0.10 0.10 0.10 0.10 0.10 0.10
10.01 and over 0.15 0.15 0.15 0.15 0.15 0.15
Chromium Up to and incl 0.90 0.03 0.04 0.04 0.05 0.05 0.06
0.91 to 2.10, incl 0.05 0.06 0.06 0.07 0.07 0.08
2.11 to 10.00, incl 0.10 0.10 0.12 0.14 0.15 0.16
10.01 to 15.00, incl 0.15 0.15 0.15 0.17 0.17 0.19
15.01 to 20.00, incl 0.20 0.20 0.20 0.22 0.24 0.24
20.01 and over 0.25 0.25 0.25 0.27 0.27 0.29
Molybdenum Up to and incl 0.20 0.01 0.02 0.02 0.02 0.03 0.03
0.21 to 0.40, incl 0.02 0.03 0.03 0.03 0.04 0.04
0.41 to 1.15, incl 0.03 0.04 0.05 0.06 0.07 0.08
1.16 to 5.50, incl 0.05 0.06 0.08 0.10 0.12 0.12
Vanadium Up to and incl 0.10 0.01 0.01 0.01 0.01 0.01 0.01
0.11 to 0.25, incl 0.02 0.02 0.02 0.02 0.02 0.02
0.26 to 0.50, incl 0.03 0.03 0.03 0.03 0.03 0.03
0.51 to 1.25, incl 0.04 0.04 0.04 0.04 0.04 0.04
B
Columbium (Niobium) Up to and incl 0.14 0.02 0.02 0.02 0.02 0.03 0.03
0.15 to 0.50, incl 0.06 0.06 0.06 0.06 0.07 0.08
Titanium Up to and incl 0.85 0.05 0.05 0.05 0.05 0.05 0.05
Cobalt Up to and incl 0.25 0.01 0.01 0.01 0.01 0.01 0.01
0.25 to 5.00, incl 0.07 0.07 0.07 0.08 0.08 0.09
5.01 to 10.00, incl 0.14 0.14 0.14 0.16 0.16 0.18
Tungsten Up to and incl 1.00 0.05 0.05 0.05 0.06 0.06 0.07
1.01 to 4.00, incl 0.09 0.09 0.10 0.12 0.12 0.14
Copper Up to and incl 1.0 0.03 0.03 0.03 0.03 0.03 0.03
1.01 to 2.00, incl 0.05 0.05 0.05 0.05 0.05 0.05
2.01 to 5.00, incl 0.07 0.07 0.07 0.07 0.07 0.07
Aluminum Up to and incl 0.03 0.01 0.01 0.01 0.01 0.01 0.01
Over 0.03 to 0.05, incl 0.01 0.01 0.02 0.02 0.03 0.03
0.06 to 0.15, incl 0.02 0.02 0.02 0.03 0.03 0.03
0.16 to 0.50, incl 0.05 0.05 0.06 0.07 0.07 0.08
0.50 to 2.00, incl 0.10 0.10 0.10 0.12 0.12 0.14
Zirconium Up to and incl 0.15 0.01 0.01 0.01 0.01 0.01 0.01
Nitrogen Up to 0.02 incl 0.005 0.005 0.005 0.005 0.005 0.005
Over 0.02 to 0.19, incl 0.01 0.01 0.01 0.01 0.01 0.01
Over 0.19 to 0.25, incl 0.02 0.02 0.02 0.02 0.02 0.02
Over 0.25 to 0.35, incl 0.03 0.03 0.03 0.03 0.03 0.03
Over 0.35 to 0.45, incl 0.04 0.04 0.04 0.04 0.04 0.04
A 2 2 2 2 2 2
When the product size range up to 100 in. [650 cm ] is deleted, then the 100 in. to 200 in. [650 cm to 1300 cm ] column shall be changed to read up to and including
2 2
200 in. [1300 cm ].
B
Columbium (Cb) and Niobium (Nb) are alternate names for element 41 in the Periodic Table of the Elements.
10.3.2 If the average impact energy value meets the speci- prescribed in the material specification, a retest is permitted.
fication requirements, but the energy value for one specimen is This shall consist of two impact specimens from a location
below the specified minimum value for individual specimens adjacent to and on either side of the specimen that failed. Each
A788/A788M − 23
of the retested specimens must exhibit an energy value equal to 16.1.2 Forging identification number,
or greater than the minimum average value required by the 16.1.3 The product specification number, including the year
product specification.
date and revision letter if any, as well as the appropriate class,
type, and grade,
11. Reheat Treatment
16.1.3.1 Reference to Specification A788/A788M including
11.1 If the results of the initial mechanical tests do not the year date together with the applicable revision letter, if any,
conform to the specified requirements, the forgings may be of the revision used shall be a part of the certification.
heat treated (if initially tested in the as-forged condition) or
16.1.4 Heat number and analysis,
reheat treated (if heat treated prior to initial testing).
16.1.5 Results of the required acceptance tests for mechani-
cal properties,
12. Repair Welding
16.1.6 Results of any required nondestructive examinations,
12.1 Repair welding of forgings is not permitted unless
16.1.7 Final heat treatment cycle including austenitizing
specifically allowed by the product specification (see also
and tempering temperatures and holding times and cooling
4.2.4).
methods if required by the product specification or 4.2.3,
16.1.8 Extent to which the forging is incomplete with
13. Dimensions and Finish
respect to the product specification (see 1.4 and 16.1.7), and
13.1 The forgings shall conform to the dimensions,
16.1.9 Results of any supplementary and additional test
tolerances, and finishes required by the ordering information
requirements that were specified.
(4.1.2). Supplementary Requirements S5 or S6, concerning
16.1.10 The material test report may be sent to the purchaser
straightening of forgings, may be used.
in electronic form from an electronic data interchange (EDI)
13.2 When surface finish, roughness, or texture is specified transmission, and this shall be regarded as having the same
validity as a counterpart printed in the certifier’s facility. The
in a steel forging product standard, unless otherwise required
by the purchaser, the roughness average (Ra), as defined in content of the EDI transmitted document shall meet the
requirements of the invoked ASTM standard(s) and conform to
ANSI/ASME B46.1, shall be used (see 4.1.2).
any existing EDI agreement between the purchaser and the
14. Inspection
supplier. Notwithstanding the absence of a signature, the
organization submitting the EDI transmission is responsible for
14.1 The manufacturer is responsible for the performance of
the content of the report.
all inspection and test requirements specified. The absence of
any inspection requirements in the specification shall not
17. Packaging and Package Marking
relieve the contractor of the responsibility for ensuring that all
products comply with all requirements of the contract. The
17.1 Each forging shall be legibly identified as required by
manufacturer may use his own or any other suitable facilities
the product specification and instructions from the purchaser.
for the performance of the inspection and test requirements
When not otherwise defined, each forging shall be identified by
unless disapproved by the purchaser at the time the order is
the manufacturer as follows:
placed.
17.1.1 Manufacturer’s name or symbol.
14.2 The manufacturer shall afford the purchaser’s inspector
17.1.2 Manufacturer’s identification or heat number.
all reasonable facilities necessary to satisfy him that the
17.1.3 Product specification number.
material is being produced and furnished in accordance with
17.1.4 The class, grade, and type identification as
the material specification.
appropriate.
17.1.5 Purchaser’s identification (4.2.3).
14.3 Mill inspection by the purchaser shall not interfere
17.1.6 Location of stamping (4.2.3).
unnecessarily with the manufacturer’s operations.
17.1.7 Incomplete forging (1.4). The marking shall include
15. Rejection
the suffix Y immediately following the ASTM number, and
15.1 Any rejection based on the presence of an injurious preceding any other suffix. This suffix shall not be removed
defect found subsequent to acceptance at the manufacturer’s until the material specification requirements have been com-
pleted and the material test report supplemented.
works or based on the results of a product analysis made in
accordance with 8.4 shall be reported to the manufacturer.
17.1.8 Dual marking with the product specification number,
grade or marking symbol, and class is acceptable provided the
15.2 Disposition of forgings rejected by the purchaser under
material meets all the requirements for each specification with
15.1 shall be as agreed upon between manufacturer and the
which it is marked.
purchaser.
17.2 Marking shall be done by impression stamping or other
16. Certification
acceptable means specified in the product specification or
16.1 The manufacturer shall furnish to the purchaser the order. Bar coding is an acceptable supplemental identification
number of copies of the material test report specified in the method. The purchaser may specify in the order a specific bar
ordering information (4.1.3.2). The following items shall be coding system to be used. The bar coding system, if applied at
reported: the discretion of the supplier, should be consistent with one of
16.1.1 Purchase order number, the published industry standards for bar coding.
A788/A788M − 23
17.3 The specification year date and revision letter are not
required to be marked on the forgings.
18. Keywords
18.1 general delivery requirements; steel forgings—alloy;
steel forgings—carbon
SUPPLEMENTARY REQUIREMENTS
(GENERAL)
The following supplementary general requirements are common to the forging specifications listed
in this specification. These and other limitations or tests may be performed by agreement between the
supplier and purchaser. The additional requirements shall be specified in the order, and shall be
completed by the supplier before the shipme
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A788/A788M − 22a A788/A788M − 23
Standard Specification for
Steel Forgings, General Requirements
This standard is issued under the fixed designation A788/A788M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope*
1.1 This specification covers a group of common requirements that, unless otherwise specified in the individual product
specification, shall apply to steel forgings under any of the following specifications issued by ASTM:
ASTM Designation Title
A266/A266M Carbon Steel Forgings for Pressure Vessel
Components
A288 Carbon and Alloy Steel Forgings for Magnetic
Retaining Rings for Turbine Generators
A289/A289M Alloy Steel Forgings for Nonmagnetic Retain-
ing Rings for Generators
A290/A290M Carbon and Alloy Steel Forgings for Rings for
Reduction Gears
A291/A291M Steel Forgings, Carbon and Alloy, for Pinions,
Gears, and Shafts for Reduction Gears
A336/A336M Alloy Steel Forgings for Pressure and High-
Temperature Parts
A372/A372M Carbon and Alloy Steel Forgings for Thin-
Walled Pressure Vessels
A469/A469M Vacuum-Treated Steel Forgings for Generator
Rotors
A470/A470M Vacuum-Treated Carbon and Alloy Steel
Forgings for Turbine Rotors and Shafts
A471/A471M Vacuum-Treated Alloy Steel Forgings for Tur-
bine Rotor Disks and Wheels
A473 Stainless Steel Forgings
A504/A504M Wrought Carbon Steel Wheels
A508/A508M Quenched and Tempered Vacuum-Treated
Carbon and Alloy Steel Forgings for Pres-
sure Vessels
A541/A541M Quenched and Tempered Carbon and Alloy
Steel Forgings for Pressure Vessel Compo-
nents
A579/A579M Superstrength Alloy Steel Forgings
A592/A592M High-Strength Quenched and Tempered Low-
Alloy Steel Forged Parts for Pressure Ves-
sels
A646/A646M Premium Quality Alloy Steel Blooms and Bil-
lets for Aircraft and Aerospace Forgings
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee A01.06
on Steel Forgings and Billets.
Current edition approved Sept. 1, 2022Sept. 1, 2023. Published September 2022September 2023. Originally approved in 1984. Last previous edition approved in 2022
as A788/A788MA788/A788M – 22a.–22. DOI: 10.1520/A0788_A0788M-22A.10.1520/A0788_A0788M-23.
For ASME Boiler and Pressure Vessel Code applications, see related Specification SA–788 in Section II of that code.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A788/A788M − 23
A649/A649M Forged Steel Rolls Used for Corrugating Pa-
per Machinery
A668/A668M Steel Forgings, Carbon and Alloy, for General
Industrial Use
A705/A705M Age-Hardening Stainless Steel Forgings
A711/A711M Steel Forging Stock
A723/A723M Alloy Steel Forgings for High-Strength Pres-
sure Component Application
A729/A729M Carbon and Alloy Steel Axles, Heat Treated,
for Mass Transit and Electric Railway Ser-
vice
A765/A765M Carbon Steel and Low-Alloy Steel Pressure-
Vessel-Component Forgings with Manda-
tory Toughness Requirements
A837/A837M Steel Forgings, Alloy, for Carburizing Applica-
tions
A859/A859M Age-Hardening Alloy Steel Forgings for Pres-
sure Vessel Components
A891/A891M Precipitation Hardening Iron Base Superalloy
Forgings for Turbine Rotor Disks and
Wheels
A909/A909M Steel Forgings, Microalloy, for General Indus-
trial Use
A965/A965M Steel Forgings, Austenitic, for Pressure and
High Temperature Parts
A982/A982M Steel Forgings, Stainless, for Compressor
and Turbine Airfoils
A983/A983M Continuous Grain Flow Forged Carbon and
Alloy Steel Crankshafts for Medium Speed
Diesel Engines
A986/A986M Magnetic Particle Examination of Continuous
Grain Flow Crankshaft Forgings
A1021/A1021M Martensitic Stainless Steel Forgings and
Forging Stock for High-Temperature Ser-
vice
A1049/A1049M Stainless Steel Forgings, Ferritic/Austenitic
(Duplex), for Pressure Vessels and Related
Components
A1090/A1090M Forged Rings and Hollows for Use as Base
Plates in Power Transmission Structures
1.2 In case of conflict in requirements, the requirements of the individual product specifications shall prevail over those of this
specification.
1.3 The purchaser may specify additional requirements (see 4.2.3) that do not negate any of the provisions of either this
specification or of the individual product specifications. The acceptance of any such additional requirements shall be dependent
on negotiations with the supplier and must be included in the order.
1.4 If, by agreement, forgings are to be supplied in a partially completed condition, that is, all of the provisions of the product
specification have not been filled, then the material marking (see Section 17) and certification (see Section 16) shall reflect the
extent to which the product specification requirements have been met.
1.5 As noted in the Certification Section (16), the number and year date of this specification, as well as that of the product
specification, are required to be included in the product certification.
1.6 When the SI version of a product specification is required by the purchase order, Specification A788/A788M shall be used in
conjunction with Test Methods A1058 instead of Test Methods and Definitions A370.
1.7 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used
independently of the other and values from the two systems shall not be combined.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
A788/A788M − 23
1.9 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
A266/A266M Specification for Carbon Steel Forgings for Pressure Vessel Components
A275/A275M Practice for Magnetic Particle Examination of Steel Forgings
A288 Specification for Carbon and Alloy Steel Forgings for Magnetic Retaining Rings for Turbine Generators
A289/A289M Specification for Alloy Steel Forgings for Nonmagnetic Retaining Rings for Generators (Withdrawn 2023)
A290/A290M Specification for Carbon and Alloy Steel Forgings for Rings for Reduction Gears
A291/A291M Specification for Steel Forgings, Carbon and Alloy, for Pinions, Gears and Shafts for Reduction Gears
A336/A336M Specification for Alloy Steel Forgings for Pressure and High-Temperature Parts
A370 Test Methods and Definitions for Mechanical Testing of Steel Products
A372/A372M Specification for Carbon and Alloy Steel Forgings for Thin-Walled Pressure Vessels
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A469/A469M Specification for Vacuum-Treated Steel Forgings for Generator Rotors
A470/A470M Specification for Vacuum-Treated Carbon and Alloy Steel Forgings for Turbine Rotors and Shafts
A471/A471M Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
A473 Specification for Stainless Steel Forgings
A504/A504M Specification for Wrought Carbon Steel Wheels
A508/A508M Specification for Quenched and Tempered Vacuum-Treated Carbon and Alloy Steel Forgings for Pressure Vessels
A541/A541M Specification for Quenched and Tempered Carbon and Alloy Steel Forgings for Pressure Vessel Components
A551/A551M Specification for Carbon Steel Tires for Railway and Rapid Transit Applications
A579/A579M Specification for Superstrength Alloy Steel Forgings
A592/A592M Specification for High-Strength Quenched and Tempered Low-Alloy Steel Forged Parts for Pressure Vessels
A646/A646M Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings
A649/A649M Specification for Forged Steel Rolls Used for Corrugating Paper Machinery
A668/A668M Specification for Steel Forgings, Carbon and Alloy, for General Industrial Use
A705/A705M Specification for Age-Hardening Stainless Steel Forgings
A711/A711M Specification for Steel Forging Stock
A723/A723M Specification for Alloy Steel Forgings for High-Strength Pressure Component Application
A729/A729M Specification for Carbon and Alloy Steel Axles, Heat-Treated, for Mass Transit and Electric Railway Service
A751 Test Methods and Practices for Chemical Analysis of Steel Products
A765/A765M Specification for Carbon Steel and Low-Alloy Steel Pressure-Vessel-Component Forgings with Mandatory
Toughness Requirements
A833 Test Method for Indentation Hardness of Metallic Materials by Comparison Hardness Testers
A837/A837M Specification for Steel Forgings, Alloy, for Carburizing Applications
A859/A859M Specification for Age-Hardening Alloy Steel Forgings for Pressure Vessel Components
A891/A891M Specification for Precipitation Hardening Iron Base Superalloy Forgings for Turbine Rotor Disks and Wheels
A909/A909M Specification for Steel Forgings, Microalloy, for General Industrial Use
A939/A939M Practice for Ultrasonic Examination from Bored Surfaces of Cylindrical Forgings (Withdrawn 2021)
A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
A965/A965M Specification for Steel Forgings, Austenitic, for Pressure and High Temperature Parts
A966/A966M Practice for Magnetic Particle Examination of Steel Forgings Using Alternating Current
A982/A982M Specification for Steel Forgings, Stainless, for Compressor and Turbine Airfoils
A983/A983M Specification for Continuous Grain Flow Forged Carbon and Alloy Steel Crankshafts for Medium Speed Diesel
Engines
A986/A986M Specification for Magnetic Particle Examination of Continuous Grain Flow Crankshaft Forgings
A991/A991M Test Method for Conducting Temperature Uniformity Surveys of Furnaces Used to Heat Treat Steel Products
A1021/A1021M Specification for Martensitic Stainless Steel Forgings and Forging Stock for High-Temperature Service
A1049/A1049M Specification for Stainless Steel Forgings, Ferritic/Austenitic (Duplex), for Pressure Vessels and Related
Components
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
A788/A788M − 23
A1058 Test Methods for Mechanical Testing of Steel Products—Metric
A1090/A1090M Specification for Forged Rings and Hollows for Use as Base Plates in Power Transmission Structures
E23 Test Methods for Notched Bar Impact Testing of Metallic Materials
E112 Test Methods for Determining Average Grain Size
E165/E165M Practice for Liquid Penetrant Testing for General Industry
E380 Practice for Use of the International System of Units (SI) (the Modernized Metric System) (Withdrawn 1997)
E399 Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic Materials
E428 Practice for Fabrication and Control of Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic Testing
(Withdrawn 2019)
E1290 Test Method for Crack-Tip Opening Displacement (CTOD) Fracture Toughness Measurement (Withdrawn 2013)
E1316 Terminology for Nondestructive Examinations
E1820 Test Method for Measurement of Fracture Toughness
E1916 Guide for Identification of Mixed Lots of Metals
2.2 Other Standards:
ANSI/ASME B46.1 Surface Texture (Surface Roughness, Waviness and Lay)
ASME Boiler and Pressure Vessel Code
SAE AMS 2750 Pyrometry
3. Terminology
3.1 Definitions of Terms—TerminologyFor A941 is applicable to this specification. Additional terms and wording more applicable
to forgings are as noteddefinitions of terms used in this standard that are not included in 3.2 – 3.5in this section., refer to the
following standards:
3.1.1 A941 Terminology Relating to Steel, Stainless Steel, Related Alloys, and Ferroalloys
3.1.2 A370 Test Methods and Definitions for Mechanical Testing of Steel Products
3.1.3 A751 Test Methods and Practices for Chemical Analysis of Steel Products
3.1.4 E1316 Terminology for Nondestructive Examinations
3.2 Forging Definitions:
3.2.1 steel forging, n—the product of a substantially compressive plastic working operation that consolidates the material and
produces the desired shape. The plastic working may be performed by a hammer, press, forging machine, or ring rolling machine,
and must deform the material to produce an essentially wrought structure.
3.2.1.1 Discussion—
Hot rolling operations may be used to produce blooms or billets for reforging.
3.3 Forging Geometries:
3.3.1 bar forging, n—forging that has no bore and having an axial length greater than its maximum cross sectional dimension.
3.3.1.1 Discussion—
More than one cross sectional shape or size may be included. Sometimes referred to as a solid forging.
3.3.2 disk forging, n—forging, sometimes referred to as a pancake forging, that has (a) an axial length appreciably less than its
diameter, (b) may be dished on one or both faces, and (c) final forging includes upsetting operations to reduce the height of the
stock and increase its diameter.
3.3.2.1 Discussion—
Since much of the hot working is done in axially compressing the stock, the central area may not receive sufficient consolidation.
To counter this effect, consideration is usually given to the initial saddening (see 3.3.6) of the ingot or billet.
3.3.3 hollow forging, n—forging (also known as a shell forging or a mandrel forging) in which (a) the axial length is equal to or
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
Available from American Society of Mechanical Engineers (ASME), ASME International Headquarters, Two Park Ave., New York, NY 10016-5990, http://
www.asme.org.
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
A788/A788M − 23
greater than the diameter, and (b) the forging length and wall thickness are produced by hot working over a mandrel (usually water
cooled) such that the bore diameter remains essentially the same as that of the mandrel.
3.3.3.1 Discussion—
Unless a hollow ingot has been used, the starting slug is hot trepanned or punched after upsetting and the bore diameter adjusted
to suit the forging mandrel. The outside diameter may be contoured if required. The workpiece is forged between the upper die
and lower dies while the mandrel is supported by cranes or manipulators to facilitate rotation.
3.3.4 ring forging, n—type of hollow forging in which (a) the axial length is less than the diameter, (b) the wall thickness is
reduced, and (c) the outside diameter is increased by hot working between the top die and a mandrel supported on temporary
saddles.
3.3.4.1 Discussion—
Forging between the top die and the mandrel enables the ring diameter to be increased while reducing the wall thickness, without
increasing the axial length.
3.3.5 ring rolling, n—involves the use of specialized equipment whereby a hot punched, hot-punched, trepanned, or bored disk
is (a) hot worked between a powered outer roller and an idling inner roller, such that the wall thickness is reduced and the outside
diameter is increased, and (b) the axial length of the ring is not intended to increase and may be contained by a radially oriented
tapered roller.
3.3.6 saddening, n—term used in the open die forging industry to describe the initial hot working of an ingot for surface
compaction and flute working surface prior to full working of the ingot cross section.
3.3.6.1 Discussion—
The term is also extended to initial hot working intended to give consolidation of ingot central areas prior to upsetting when making
products such as turbine and generator rotors and tube sheets.
3.3.7 slab forging, n—forging, sometimes referred to as a forged plate, that is usually square or rectangular in shape, with a
thickness appreciably smaller than the other dimension. The hot working may include upsetting.
3.4 billets and blooms, n—interchangeable terms representing hot-worked semi-finished product intended as a starting stock for
making forgings.
3.4.1 Discussion—No size limitations are assumed for either term. Cast shapes produced by a continuous casting process, without
subsequent work, are considered to be ingots for the purposes of this specification, and if supplied as billets or blooms must carry
the descriptor Cast Billet or Cast Bloom.
3.5 Definitions of Terms Specific to This Standard:
3.5.1 bottom pouring, n—steel from a single heat, or from a multiple heat tapped into a common ladle (see 8.1.1 and 8.1.2),
introduced into ingot mold(s) such that they are filled from the bottom up. One or more molds can be set up on an individual plate,
and more than one plate may be poured in sequence from a heat.
3.5.2 ingot, n—the product obtained when molten steel, upon being cast into a mold, is subsequently capable of being wrought
to produce forgings. Bottom poured, top poured, or remelted ingots as well as continuous strand cast product are included in this
definition.
3.5.3 intercritical heat treatment, n—use of a multi-stage heat treatment procedure in which the material is first austenitized at a
temperature above the upper critical temperature (Ac3) followed by cooling below the lower critical temperature (Ac1). The
material is then reheated to a temperature in the intercritical range between the Ac1 and the Ac3 and again cooled below the Ac1,
followed by subcritical tempering in the range specified in the material specification.
3.5.3.1 Discussion—
This procedure is generally applicable to low hardenability carbon and low alloy steels that would usually have a microstructure
of ferrite and pearlite in the heat treated section size of the component being heat treated.
3.5.4 precipitation deoxidation, n—steelmaking process in which primary deoxidation is achieved by the addition of strong
deoxidizing agents, such as aluminum, early in the process, and holding the steel in the molten state for sufficient time for the
products of deoxidation to separate from the melt to the slag.
A788/A788M − 23
3.5.5 sequential or continuous strand casting, n—steel from several heats poured consecutively into a cooled open-ended mold
to form a continuous cast product with a change from heat to heat along its length (see 8.1.5).
3.5.6 strand casting, n—steel from one heat poured into a cooled open-ended mold to form a continuous strand or strands.
3.5.7 vacuum carbon deoxidation (VCD), n—steelmaking process in which primary deoxidation occurs during vacuum treatment
as a result of the carbon-oxygen reaction. In order for primary deoxidation to occur during vacuum treatment, deoxidizing agents
such as aluminum or silicon are not to be added to the melt in any significant amount prior to the vacuum treatment operation.
4. Ordering Information
4.1 It shall be the responsibility of the purchaser to specify all requirements that are necessary for forgings under the applicable
product specification. Such requirements to be considered include, but are not restricted to, the following:
4.1.1 Quantity,
4.1.2 Dimensions, including tolerances and surface finishes.
4.1.3 Specification number with type, class, and grade as applicable (including year date), and should include:
4.1.4 Number of copies of the material test report.
4.1.3 Choice of testing track from the options listed in Test Methods Specification number with type, class, and grade A1058 when
forgings are ordered to a suffix M product standard. If the choice of test track is not made in the ordering information then the
default ASTM track shall be used as noted in Test Methodsas applicable (including year date), A1058.and should include:
4.1.3.1 Number of copies of the material test report.
4.1.3.2 Choice of testing track from the options listed in Test Methods A1058 when forgings are ordered to a suffix M product
standard. If the choice of test track is not made in the ordering information then the default ASTM track shall be used as noted
in Test Methods A1058.
4.2 Additional information including the following may be added by agreement with the supplier:
4.2.1 Type of heat treatment when alternative methods are allowed by the product specification,
4.2.2 Supplementary requirements, if any, and
4.2.3 Additional requirements (see 1.4, 16.1.6, 16.1.7, and 16.1.9).
4.2.4 Repair welding NOT permitted.
4.3 For dual format specifications, unless otherwise specified, the inch-pound units shall be used.
5. Melting Process
5.1 Unless otherwise specified in the product specification, the steel shall be produced by any of the following primary processes:
electric-furnace (EF), basic oxygen (BOF), or vacuum-induction (VIM). The primary melting may incorporate separate degassing
or refining and may be followed by secondary processes such as, but not limited to, argon-oxygen decarburization (AOD),
vacuum-oxygen decarburization (VOD), or vacuum degassing (VD). The steel may additionally undergo electro slag remelting
(ESR) or vacuum arc remelting (VAR).
5.1.1 The steel shall be fully killed.
5.2 The molten steel may be vacuum-treated prior to or during pouring of the ingot.
A788/A788M − 23
5.2.1 When vacuum treatment of the molten steel is required by the product specification the following conditions shall apply:
5.2.1.1 When the vacuum stream degassing process is used, the vacuum system must be of sufficient capacity to effect a blank-off
pressure low enough (usually less than 1000 μm) to break up the normal tight, rope-like stream of molten metal into a wide-angled
conical stream of relatively small droplets. The capacity of the system must also be sufficiently high to reduce the initial surge
pressure at the start of the pour to a low level within 2 min.
5.2.1.2 When the vacuum-lift process is utilized, the molten metal shall be repeatedly drawn into the evacuated vessel to give a
recirculation factor (see Annex A1) of at least 2.5 to ensure thorough degassing and mixing of the entire heat. The evacuation
system shall be capable of reducing the pressure surges, which occur each time a new portion of steel is admitted to the vessel
to increasingly lower levels, until a blank-off pressure (usually less than 1000 μm) is achieved signifying the end of the degassing
treatment.
5.2.1.3 When the ladle degassing process is used, the evacuation system shall be capable of reducing the system vacuum pressure
to a low level (usually less than 1000 μm). The molten metal shall be adequately stirred for a sufficient length of time to maximize
exposure to the evacuated atmosphere.
5.2.1.4 Other methods of vacuum treatment may be used if the supplier can demonstrate adequate degassing and acceptable
properties in the finished forging to the satisfaction of the purchaser.
6. Forging
6.1 Forgings shall be made in accordance with 3.2.1.
6.2 Because of differences in manufacture, hot-rolled, or hot-rolled and cold-finished bars (semi-finished or finished), billets, or
blooms are not considered to be forgings.
6.3 Cold worked forgings shall be made from material previously hot worked by forging or rolling; however, a hot-cold worked
forging may be produced in one continuous operation wherein the material is first hot worked and then cold worked by control
of the finishing temperature.
7. Cooling Prior to Heat Treatment
7.1 After forging and before reheating for heat treatment, the forgings shall be allowed to cool in such a manner as to prevent
injury and, in the case of ferritic forgings, to permit substantially complete transformation of austenite.
8. Chemical Composition
8.1 Heat Analysis:
8.1.1 An analysis of each heat of steel shall be made by the steel producer to determine the percentages of those elements specified
in the product specification. This analysis shall be made from a test sample preferably taken during the pouring of the heat and
shall conform to the requirements of the product specification.
8.1.2 When multiple heats are tapped into a common ladle, the ladle chemistry shall apply. The chemical composition thus
determined shall conform to the requirements of the product specification.
8.1.3 For multiple-heat ingots, either individual heat analyses or a weighted average (see Annex A2) may be taken. The results
of the method used shall conform to the requirements of the product specification.
8.1.4 With the exception of the product from multiple heats sequentially cast in strand casting machines (see 8.1.5), if the test
sample taken for a heat analysis is lost or declared inadequate for chemical determinations, the steel producer may take alternative
samples from appropriate locations near the surface of the ingot or forging as necessary to establish the analysis of the heat in
question.
8.1.5 For multiple heats sequentially cast in strand casting machines, the heat analysis shall be determined for each individual heat
in accordance with 8.1.1 or 8.1.2 if applicable.
A788/A788M − 23
8.1.5.1 If, for multiple heats sequentially strand cast, the test sample is lost or declared inadequate for chemical analysis
determination, alternative samples, remote from the transition zones, may be taken by the steel producer from the cast material or
product of that heat, as defined in 8.2 or 8.3 as appropriate.
8.1.6 Heat Analysis for Remelted Ingots:
8.1.6.1 When consumable remelting processes are used, a chemical analysis shall be taken from a remelted ingot (or the product
of a remelted ingot) for the remelt heat analysis.
8.1.6.2 When more than one electrode is prepared from a master or parent heat for remelting in the same facility by the same
process, then the heat analysis obtained from one remelted ingot, or the product from that ingot, shall be taken as the heat analysis
for all of the remelted ingots from that master heat. For analysis from each remelted ingot, see Supplementary Requirement S27.
8.1.6.3 When electrodes from different master heats are remelted sequentially, an analysis shall be made in each zone of the
remelted ingot corresponding to at least one electrode from each master heat. The resultant chemical analysis of each zone shall
conform to the requirements of the product specification. The heat analysis of the remelted ingot shall be represented by a weighted
average (see Annex A2) of the individual chemical analyses for each zone.
8.1.6.4 Limits on aluminum content in remelt ingots shall be set as required in the product specification.
8.2 Heat Number Assignment for Sequentially Strand Cast Material—When heats of the same chemical composition are
sequentially strand cast, the heat number assigned to the cast product may remain unchanged until all of the steel in the product
is from the following heat, except when Supplementary Requirement S3 is invoked.
8.3 Identification of Material of Different Chemical Composition Ranges, Sequentially Strand Cast—Because of intermixing in the
tun dish, separation and identification of the resultant transition material is required when steels of different chemical composition
ranges are sequentially strand cast. The steel producer shall remove the transition material by any established procedure that
positively separates the grades.
8.4 Product Analysis:
8.4.1 An analysis may be made by the purchaser from a forging representing each heat or multiple heat (see 8.1). Samples for
analysis may be taken from the forging or from a full-size prolongation. The sampling location shall be at any point from the
midradius to the outer surface of disk or other solid forgings. For hollow or bored forgings, the sampling location shall be at any
point from the midwall of the hollow configuration to the outer surface. The analysis may also be taken from a mechanical test
specimen or the mechanical test location as defined in the product specification.
8.4.2 The chemical composition thus determined shall conform to the heat analysis requirements of the forging specification
subject to the permissible variations specified in Table 1, for those elements listed in the product specification. Limitations on the
application of the allowances in Table 1 may be made in the product specification for specified elements.
8.4.3 Limits on formula calculations involving elemental contents shall apply only to the heat analysis, unless agreed upon
between supplier and purchaser. Where limits on formula calculations involving elemental contents apply to product analysis by
such agreement, permissible variations in the formula calculation results beyond the limits for the heat analysis shall also be agreed
upon between supplier and purchaser. Examples of such formula calculations include, but are not limited to, the following:
carbon equivalent CE 5
C1Mn/61 Cr 1 Mo 1 V ⁄51 Ni 1 Cu ⁄15 (1)
~ ! ~ !
J factor 5 Mn 1 Si × P 1 Sn ×10 (2)
~ ! ~ !
requirements for specific elemental balance or sufficiency,
typically related to Ti, Nb, or Al and interstitials C and N,
such as Nb 5 5 ×C minimum. (3)
8.5 Residual and Unspecified Elements—Provisions for the limitation of certain residual and unspecified elements have been made
in Supplementary Requirements S1 and S2, respectively.
A788/A788M − 23
TABLE 1 Permissible Variations in Product Analysis for Killed Steel
NOTE 1—This table covers permissible variations in product analysis for most of the elements commonly found in killed steels under the jurisdiction
of A01.06. This table is applicable only for those elements for which product analysis variations are permitted by the material specification. The listed
variation value is subtracted from the minimum specified limit, or added to the maximum specified limit for the heat analysis in the product specification.
NOTE 2—Product cross-sectional area (taken at right angles to the axis of the original ingot or billet) is defined as either: (1) maximum cross-sectional
area of a bored forging excluding the bored region, (2) maximum cross-sectional area of the unmachined forging, or (3) maximum cross-sectional area
of the billet bloom or slab.
Permissible Variation Over the Specified Maximum Limit or Under the Specified Minimum Limit
2A 2 2 2 2
Element Maximum or Up to and Over 100 in. to Over 200 in. to Over 400 in. to Over 800 in. to Over 1600 in.
2 2 2 2
200 in. incl
Specified Range—I incl 100 in. 400 in. incl 800 in. incl 1600 in. incl [over 10 300
[650 cm to
2 A 2 2 2 2
[650 cm ] [1300 cm to [2600 cm to [5200 cm to cm ]
1300 cm ]
2 2 2
2600 cm ] 5200 cm ] 10 300 cm ]
Carbon Up to and incl 0.05 0.005 0.005 0.005 0.01 0.01 0.01
0.06 to 0.10, incl 0.01 0.01 0.01 0.01 0.01 0.01
0.11 to 0.25, incl 0.02 0.03 0.03 0.04 0.05 0.05
0.26 to 0.55, incl 0.03 0.04 0.04 0.05 0.06 0.06
0.56 and over 0.04 0.05 0.05 0.06 0.07 0.07
Manganese Up to and incl 0.90 0.03 0.04 0.05 0.06 0.07 0.08
0.91 and over 0.06 0.06 0.07 0.08 0.08 0.09
Phosphorus Up to and incl 0.05 0.008 0.008 0.010 0.010 0.015 0.015
Sulfur Up to and incl 0.030 0.005 0.005 0.005 0.005 0.006 0.006
0.031 to 0.060 incl 0.008 0.010 0.010 0.010 0.015 0.015
Silicon Up to and incl 0.35 0.02 0.03 0.04 0.04 0.05 0.06
0.36 and over 0.05 0.06 0.06 0.07 0.07 0.08
Nickel Up to and incl 1.00 0.03 0.03 0.03 0.03 0.03 0.03
1.01 to 2.00, incl 0.05 0.05 0.05 0.05 0.05 0.05
2.01 to 5.30, incl 0.07 0.07 0.07 0.07 0.07 0.07
5.31 to 10.00, incl 0.10 0.10 0.10 0.10 0.10 0.10
10.01 and over 0.15 0.15 0.15 0.15 0.15 0.15
Chromium Up to and incl 0.90 0.03 0.04 0.04 0.05 0.05 0.06
0.91 to 2.10, incl 0.05 0.06 0.06 0.07 0.07 0.08
2.11 to 10.00, incl 0.10 0.10 0.12 0.14 0.15 0.16
10.01 to 15.00, incl 0.15 0.15 0.15 0.17 0.17 0.19
15.01 to 20.00, incl 0.20 0.20 0.20 0.22 0.24 0.24
20.01 and over 0.25 0.25 0.25 0.27 0.27 0.29
Molybdenum Up to and incl 0.20 0.01 0.02 0.02 0.02 0.03 0.03
0.21 to 0.40, incl 0.02 0.03 0.03 0.03 0.04 0.04
0.41 to 1.15, incl 0.03 0.04 0.05 0.06 0.07 0.08
1.16 to 5.50, incl 0.05 0.06 0.08 0.10 0.12 0.12
Vanadium Up to and incl 0.10 0.01 0.01 0.01 0.01 0.01 0.01
0.11 to 0.25, incl 0.02 0.02 0.02 0.02 0.02 0.02
0.26 to 0.50, incl 0.03 0.03 0.03 0.03 0.03 0.03
0.51 to 1.25, incl 0.04 0.04 0.04 0.04 0.04 0.04
B
Columbium (Niobium) Up to and incl 0.14 0.02 0.02 0.02 0.02 0.03 0.03
0.15 to 0.50, incl 0.06 0.06 0.06 0.06 0.07 0.08
Titanium Up to and incl 0.85 0.05 0.05 0.05 0.05 0.05 0.05
Cobalt Up to and incl 0.25 0.01 0.01 0.01 0.01 0.01 0.01
0.25 to 5.00, incl 0.07 0.07 0.07 0.08 0.08 0.09
5.01 to 10.00, incl 0.14 0.14 0.14 0.16 0.16 0.18
Tungsten Up to and incl 1.00 0.05 0.05 0.05 0.06 0.06 0.07
1.01 to 4.00, incl 0.09 0.09 0.10 0.12 0.12 0.14
Copper Up to and incl 1.0 0.03 0.03 0.03 0.03 0.03 0.03
1.01 to 2.00, incl 0.05 0.05 0.05 0.05 0.05 0.05
2.01 to 5.00, incl 0.07 0.07 0.07 0.07 0.07 0.07
Aluminum Up to and incl 0.03 0.01 0.01 0.01 0.01 0.01 0.01
Over 0.03 to 0.05, incl 0.01 0.01 0.02 0.02 0.03 0.03
0.06 to 0.15, incl 0.02 0.02 0.02 0.03 0.03 0.03
0.16 to 0.50, incl 0.05 0.05 0.06 0.07 0.07 0.08
0.50 to 2.00, incl 0.10 0.10 0.10 0.12 0.12 0.14
Zirconium Up to and incl 0.15 0.01 0.01 0.01 0.01 0.01 0.01
Nitrogen Up to 0.02 incl 0.005 0.005 0.005 0.005 0.005 0.005
Over 0.02 to 0.19, incl 0.01 0.01 0.01 0.01 0.01 0.01
Over 0.19 to 0.25, incl 0.02 0.02 0.02 0.02 0.02 0.02
Over 0.25 to 0.35, incl 0.03 0.03 0.03 0.03 0.03 0.03
Over 0.35 to 0.45, incl 0.04 0.04 0.04 0.04 0.04 0.04
A 2 2 2 2 2 2
When the product size range up to 100 in. [650 cm ] is deleted, then the 100 in. to 200 in. [650 cm to 1300 cm ] column shall be changed to read up to and including
2 2
200 in. [1300 cm ].
B
Columbium (Cb) and Niobium (Nb) are alternate names for element 41 in the Periodic Table of the Elements.
8.6 Grade substitution is not permitted.
A788/A788M − 23
8.7 Method of Analysis—Methods included in Test Methods and Practices A751 shall be used for referee purposes.
9. Heat Treatment
9.1 Heat treatment shall be performed as specified in the product specification. Supplementary Requirement S4 concerns a
specialized heat treat process (see 3.5.3) whose application will be controlled in the product specification. Unless otherwise
specified during a heat treating hold cycle, the recorded furnace temperature shall be within 625 °F [615 °C] of the controlling
set point temperature. Material shall be heat treated in the working zone of a furnace that has been surveyed in accordance with
Test Method A991/A991M or AMS 2750 provided that the working zone was established using a variation of 625 °F [615 °C]
or less from the furnace set point.
10. Mechanical Testing
10.1 Test Methods—Except as specified in 4.1.54.1.3.2 or 10.2.1 and 10.2.2, all tests shall be conducted in accordance with Test
Methods and Definitions A370. When forgings are ordered to SI requirements (M suffix standard) Test Methods A1058 shall be
used (see 4.1.54.1.3.2).
10.1.1 In addition to the hardness testing provisions of Test Methods and Definitions A370 or, when required, Test Methods
A1058, comparison hardness testing in accordance with Test Method A833 may be used in determining the hardness of forgings.
10.1.2 It can be impractical to hardness test larger forgings by any other method than portable hardness testing. Product standards
that state a required hardness result of HBW or HRC can have this value tested per the portable hardness testers in Test Methods
and Definitions A370. The hardness results must be presented and reported according to Test Methods and Definitions A370,
Portable Hardness Testing.
10.1.3 Unless otherwise specified, the forging weight and dimension (diameter, length, etc.) used for determining the number and
the location of mechanical properties refer to the weight and dimension at the time of heat treatment, excluding test
prolongation(s). For forgings heat treated as a multiple forging, the weight and dimensions of the multiple forging shall be used.
10.2 Fracture Appearance Transition Temperature (FATT )—For a product specification (including M suffix SI specifications) that
n
requires the determination of the fracture appearance transition temperature (FATT ) where n is the required minimum percentage
n
of shear fracture as measured on the fracture surface of a Charpy V-notch sample by one of the methods described in Test Methods
and Definitions A370, the Charpy test specimen location and orientation shall be as specified in the product standard.
10.2.1 When the actual fracture appearance transition temperature is required, break at least four specimens that have been taken
from a comparable location. Test each specimen at a different temperature such that the percentage of shear fracture will be both
above and below the value of n, but within a range of 60.60 times that of the specified value of n. It is desirable that two of the
specimens will have values of cleavage fracture above the value of n, and two will have values below this level. Plot the percentage
shear fracture against test temperature and determine the transition temperature by interpolation (extrapolation is not permitted).
10.2.2 When, rather than calling for an actual FATT as described in 10.2.1, the product specification requires a minimum FATT
n n
at a given temperature then, unless otherwise specified, a single test run at the required temperature satisfies the requirement
provided that the fracture appearance value is at least n. For example, a single test run at 100 °F [38 °C] with a fracture appearance
of 55 % shear fracture satisfies a requirement of FATT at 100 °F [38 °C].
10.3 Retests—If the results of the tests do not conform to the requirements specified, retests are permitted as outlined in Test
Methods and Definitions A370 or as follows:
10.3.1 If the percentage of elongation or reduction of area of any tension test specimen is less than specified because a flaw
becomes evident in the test specimen during testing, a retest shall be allowed provided that the defect was not attributable to
ruptures, cracks, or flakes in the steel.
10.3.2 If the average impact energy value meets the specification requirements, but the energy value for one specimen is below
the specified minimum value for individual specimens prescribed in the material specification, a retest is permitted. This shall
consist of two impact specimens from a location adjacent to and on either side of the specimen that failed. Each of the retested
specimens must exhibit an energy value equal to or greater than the minimum average value required by the product specification.
A788/A788M − 23
11. Reheat Treatment
11.1 If the results of the initial mechanical tests do not conform to the specified requirements, the forgings may be heat treated
(if initially tested in the as-forged condition) or reheat treated (if heat treated prior to initial testing).
12. Repair Welding
12.1 Repair welding of forgings is not permitted unless specifically allowed by the product specification (see also 4.2.4).
13. Dimensions and Finish
13.1 The forgings shall conform to the dimensions, tolerances, and finishes required by the ordering information (4.1.2).
Supplementary Requirements S5 or S6, concerning straightening of forgings, may be used.
13.2 When surface finish, roughness, or texture is specified in a steel forging product standard, unless otherwise required by the
purchaser, the roughness average (Ra), as defined in ANSI/ASME B46.1, shall be used (see 4.1.2).
14. Inspection
14.1 The manufacturer is responsible for the performance of all inspection and test requirements specified. The absence of any
inspection requirements in the specification shall not relieve the contractor of the responsibility for ensuring that all products
comply with all requirements of the contract. The manufacturer may use his own or any other suitable facilities for the performance
of the inspection and test requirements unless disapproved by the purchaser at the time the order is placed.
14.2 The manufacturer shall afford the purchaser’s inspector all reasonable facilities necessary to satisfy him that the material is
being produced and furnished in accordance with the material specification.
14.3 Mill inspection by the purchaser shall not interfere unnecessarily with the manufacturer’s operations.
15. Rejection
15.1 Any rejection based on the presence of an injurious defect found subsequent to acceptance at the manufacturer’s works or
based on the results of a product analysis made in accordance with 8.4 shall be reported to the manufacturer.
15.2 Disposition of forgings rejected by the purchaser under 15.1 shall be as agreed upon between manufacturer and the purchaser.
16. Certification
16.1 The manufacturer shall furnish to the purchaser the number of copies of the material test report specified in the ordering
information (4.1.44.1.3.2). The following items shall be reported:
16.1.1 Purchase order number,
16.1.2 Forging identification number,
16.1.3 The product specification number, including the year date and revision letter if any, as well as the appropriate class, type,
and grade,
16.1.3.1 Reference to Specification A788/A788M including the year date together with the applicable revision letter, if any, of the
revision used shall be a part of the certification.
16.1.4 Heat number and analysis,
16.1.5 Results of the required acceptance tests for mechanical properties,
16.1.6 Results of any required nondestructive examinations,
A788/A788M − 23
16.1.7 Final heat treatment cycle including austenitizing and tempering temperatures and holding times and cooling methods if
required by the product specification or 4.2.3,
16.1.8 Extent to which the forging is incomplete with respect to the product specification (see 1.4 and 16.1.7), and
16.1.9 Results of any supplementary and additional test requirements that were specified.
16.1.10 The material test report may be sent to the purchaser in electronic form from an electronic data interchange (EDI)
transmission, and this shall be regarded as having the same validity as a counterpart printed in the certifier’s facility. The content
of the EDI transmitted document shall meet the requirements of the invoked ASTM standard(s) and conform to any existing EDI
agreement between the purchaser and the supplier. Notwithstanding the absence of a signature, the organization submitting the EDI
transmission is responsible for the content of the report.
17. Packaging and Package Marking
17.1 Each forging shall be legibly identified as required by the product specification and instructions from the purchaser. When
not otherwise defined, each forging shall be identified by the manufacturer as follows:
17.1.1 Manufacturer’s name or symbol.
17.1.2 Manufacturer’s identification or heat number.
17.1.3 Product specification number.
17.1.4 The class, grade, and type identification as
appropriate.
17.1.5 Purchaser’s identification (4.2.3).
17.1.6 Location of stamping (4.2.3).
17.1.7 Incomplete forging (1.4). The marking shall include the suffix Y immediately following the ASTM number, and preceding
any other suffix. This suffix shall not be removed until the material specification requirements have been completed and the material
test report supplemented.
17.1.8 Dual marking with the product specification number, grade or marking symbol, and class is acceptable provided the
material meets all the requirements for each specification with which it is marked.
17.2 Marking shall be done by impress
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