ASTM A471/A471M-19(2024)
(Specification)Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
ABSTRACT
This specification covers vacuum-treated alloy steel forgings intended for use as turbine rotor disks and wheels. The steel shall be made by the basic electric-furnace process. The molten steel shall be vacuum treated using either the vacuum stream degassing process, vacuum-lift process or ladle degassing process prior to or during the pouring of the ingot in order to remove objectionable gases, particularly hydrogen. The forgings shall receive their hot mechanical work under a press, hammer, or mill of sufficient power to work the metal throughout its section. Before reheating for heat treatment, the forging shall be allowed to cool in a manner to prevent damage and to accomplish transformation. The forgings shall be heated to a suitable temperature for a sufficient length of time for complete austenitization and shall be tempered to develop the specified properties. The forgings shall be preliminarily machined on all surfaces prior to heat treatment and shall be stress relieved after machining. To measure some mechanical properties, the specimens shall be subjected to tension test, impact test, and hardness test. A non-destructive test like an ultrasonic inspection shall be made on all available surfaces to demonstrate freedom from detrimental internal indications.
SCOPE
1.1 This specification covers vacuum-treated alloy steel forgings intended for use as turbine rotor disks and wheels.
1.2 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.
1.3 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.
1.4 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.
General Information
Relations
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: A471/A471M − 19 (Reapproved 2024)
Standard Specification for
Vacuum-Treated Alloy Steel Forgings for Turbine Rotor
Disks and Wheels
This standard is issued under the fixed designation A471/A471M; 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.
1. Scope E139 Test Methods for Conducting Creep, Creep-Rupture,
and Stress-Rupture Tests of Metallic Materials
1.1 This specification covers vacuum-treated alloy steel
forgings intended for use as turbine rotor disks and wheels.
3. Ordering Information
1.2 The values stated in either SI units or inch-pound units
3.1 Material supplied to this specification shall conform to
are to be regarded separately as standard. The values stated in
the requirements of Specification A788/A788M, which out-
each system are not necessarily exact equivalents; therefore, to
lines additional ordering information, manufacturing methods
ensure conformance with the standard, each system shall be
and procedures, marking, certification, production analysis
used independently of the other, and values from the two
variations, and additional supplementary requirements.
systems shall not be combined.
3.2 The purchaser shall specify in the inquiry and order the
1.3 This standard does not purport to address all of the
class of steel desired and test and purchase options (see 4.5.5,
safety concerns, if any, associated with its use. It is the
5.2.2, 6.1, 6.3, 6.4, and Section 7).
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3.3 Forging Drawing—Each forging shall be manufactured
mine the applicability of regulatory limitations prior to use.
in accordance with a purchaser-supplied drawing showing the
1.4 This international standard was developed in accor-
finished dimensions and the locations of mechanical test
dance with internationally recognized principles on standard-
specimens.
ization established in the Decision on Principles for the
3.4 Supplementary requirements are provided and shall
Development of International Standards, Guides and Recom-
apply only when specified in the purchaser’s order.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Materials and Manufacture
2. Referenced Documents
4.1 Melting Process:
2.1 ASTM Standards: 4.1.1 The steel shall be made by the basic electric-furnace
A275/A275M Practice for Magnetic Particle Examination of process, with additional ladle refining being optional.
Steel Forgings 4.1.2 Provisions for subsequent secondary melting of the
A370 Test Methods and Definitions for Mechanical Testing steel by the consumable electrode-electroslag or vacuum-arc
of Steel Products remelting processes are included in Supplementary Require-
A388/A388M Practice for Ultrasonic Examination of Steel ment S4.
Forgings
4.2 The vacuum degassing requirements of Specification
A751 Test Methods and Practices for Chemical Analysis of
A788/A788M are mandatory.
Steel Products
4.3 Discard—Sufficient discard shall be taken from each
A788/A788M Specification for Steel Forgings, General Re-
ingot to secure freedom from pipe and undue segregation in the
quirements
finished forging.
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
4.4 Forging Process—The forgings shall receive their hot
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
mechanical work under a press, hammer, or mill of sufficient
A01.06 on Steel Forgings and Billets.
power to work the metal throughout its section. The forgings
Current edition approved March 1, 2024. Published March 2024. Originally
shall be upset by forming from a block having an axial length
approved in 1962. Last previous edition approved in 2019 as A471/A471M – 19.
DOI: 10.1520/A0471_A0471M-19R24.
before upsetting of at least two times the thickness of the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
forging after upsetting.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.4.1 The as-forged dimensions of each forging shall be
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. planned so the metal is shaped by forging as close as is
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
A471/A471M − 19 (2024)
practical to the dimensions shown on the purchaser’s drawing 4.6.2 Machining to Purchaser’s Requirements for
so as to keep subsequent machining to a minimum. Shipment—After heat treatment for mechanical properties (see
4.4.2 The axial center of the forging shall be maintained in 4.5.3), the forgings shall be machined to the dimensions of the
common with the axial center of the ingot. purchaser’s forging drawing or instructions on the order.
4.5 Heat Treatment:
5. Chemical Composition
4.5.1 Cooling Prior to Heat Treatment—After forging and
5.1 The steel shall conform to the requirements for chemical
before reheating for heat treatment, the forging shall be
composition prescribed in Table 1.
allowed to cool in a manner to prevent damage and to
accomplish transformation. 5.2 Chemical Analysis:
4.5.2 Preliminary Heat Treatment—The forgings shall be 5.2.1 Heat Analysis—An analysis of each heat of steel shall
given such preliminary heat treatment as is proper for the be made by the manufacturer to determine the percentages of
design and composition. The forgings shall be heated to a those elements specified in Table 1. This analysis shall be made
suitable temperature for a sufficient length of time for complete from a test ingot taken during the pouring of the heat.
austenitization and shall be suitably cooled to bring about 5.2.1.1 If the test sample taken for the ladle analysis is lost
complete transformation. or declared inadequate for chemical determinations, the manu-
4.5.3 Heat Treatment for Mechanical Properties—The forg-
facturer may take alternative samples from appropriate loca-
ings shall be reheated to a temperature above the upper critical tions near the surface of the ingot or forging as necessary to
temperature, held a sufficient length of time for complete
establish the analysis of the heat in question.
austenitization, and liquid quenched. 5.2.2 Product Analysis—A product analysis may be re-
4.5.4 Tempering Temperature—The forgings shall be tem- quested by the purchaser on each forging. Sample for an
pered to develop the specified properties. The final tempering analysis may be taken from the forging at any point from the
temperature for Class 1 to 6 and 11 through 14 shall be not less mid-radius to the outside diameter or from a full-size
than 1100 °F [595 °C], and for Class 10 not less than 1200 °F prolongation, or turnings may be taken from a test specimen.
[650 °C]. The forgings shall be cooled under suitable condi- The chemical composition thus determined shall not vary from
tions from the tempering temperature. the requirements specified in Table 1 more than the amounts
4.5.5 Stress Relief—Unless otherwise specified by the prescribed in Table 1 of Specification A788/A788M.
purchaser, the forgings shall be stress relieved after machining
5.3 Test Methods of Analysis—Test Methods, Practices, and
(see 4.6.2) by heating slowly to a temperature within 100 °F
Terminology A751 shall be used for referee purposes.
[55 °C] below the final tempering temperature but in no case
below 1025 °F [550 °C] for Classes 1 to 6 and 11 through 14 6. Mechanical Properties
and 1150 °F [620 °C] for Class 10. They shall be held for a
6.1 Tension Test—The material shall conform to the require-
sufficient length of time and then cooled under suitable
ment for tensile properties prescribed in Table 2 when tested in
conditions. This stress-relief temperature may be omitted
accordance with Test Methods and Definitions A370. Tension
provided the metal removed in accordance with 4.6.2, exclud-
test specimens shall be the standard round, ⁄2 in. [12.5 mm]
ing test metal, does not exceed ⁄16 in. [5 mm] on any surface.
diameter, 2 in. [50 mm] gauge length as shown in Test Methods
4.6 Machining: and Definitions A370. The yield strength prescribed in Table 2
4.6.1 Preliminary Machining—The forgings shall be pre-
shall be determined by the 0.2 % offset method of Test
liminarily machined on all surfaces prior to heat treatment for Methods and Definitions A370. The offset shall be 0.2 %
mechanical properties (see 4.5.3). unless 0.02 % is specified in the ordering information.
TABLE 1 Chemical Requirements
Composition, %
Classes 1 to 6, Class 10 Classes 11 to 13, Class 14
incl incl
A
Carbon 0.28 max 0.27–0.37 0.38–0.43 0.45 max
Manganese 0.70 max 0.70–1.00 0.60–1.00 0.60–1.00
Phosphorus 0.012 max 0.012 max 0.012 max 0.012 max
Sulfur 0.015 max 0.015 max 0.015 max 0.015 max
B B B B B
Silicon
Nickel 2.00–4.00 0.50 max 0.50 max 1.65–3.50
Chromium 0.75–2.00 0.85–1.25 0.80–1.10 0.50–1.25
Molybdenum 0.20–0.70 1.00–1.50 0.15 min 0.20 min
Vanadium 0.05 min 0.20–0.30 0.06 max optional
C C C C
Antimony
D
Aluminum 0.015 max 0.015 max 0.015 max 0.015 max
A
0.35 % C max for Classes 4 and 5; 0.40 % C, max, for Class 6.
B
0.10 % max unless an alternative value, not in excess of 0.35 %, is specified in the purchase order.
C
To be reported for information only.
D
Total of soluble and insoluble.
A471/A471M − 19 (2024)
TABLE 2 Tensile and Charpy Impact Requirements
Class 1 Class 2 Class 3 Class 4 Class 5 Class 6
Tensile strength, min, ksi [MPa] 100 105 110 120 130 140
[690] [725] [760] [830] [900] [965]
Yield strength, ksi [MPa]
0.2 % offset 80–100 90–110 100–120 110–130 120–140 130–150
[550–690] [620–760] [690–825] [760–895] [825–965] [895–1035]
0.02 % offset 75–95 85–105 95–115 105–125 115–135 125–145
[520–655] [585–725] [655–790] [725–860] [790–930] [860–1000]
Elongation in 2 in. or 50 mm, min, % 20 19 18 17 16 15
Reduction of area, min, % 50 50 47 45 43 43
Charpy V-notch impact, room temperature, ft·lbf [J], min 50 [68] 50 [68] 45 [61] 45 [61] 40 [54] 40 [54]
Transition temperature, FATT , °F [°C], max 0 [–18] 0 [–18] 0 [–18] 0 [–18] 10 [–12] 10 [–12]
Brinell hardness number . . . . . . . . . . . . . . . . . .
Class 10 Class 11 Class 12 Class 13 Class 14
Tensile strength, min, ksi [MPa] 105 100 110 125 125
[725] [690] [760] [860] [860]
Yield strength, ksi [MPa]
0.2 % offset 90–105 . . . . . . . . .
...
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