ASTM A471-08

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 inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
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 and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 30-Sep-2008
• 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

• Replaces: ASTM A471-06 - Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
• Effective Date: 01-Oct-2008
• Replaced By: ASTM A471/A471M-09 - Standard Specification for Vacuum-Treated Alloy Steel Forgings for Turbine Rotor Disks and Wheels
• Effective Date: 01-Apr-2009

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: A 471 – 08
Standard Specification for
Vacuum-Treated Alloy Steel Forgings for Turbine Rotor
1
Disks and Wheels
This standard is issued under the fixed designation A 471; 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* offset (0.2 or 0.02 %), and any tests, supplementary require-
ments, and purchase options desired.
1.1 This specification covers vacuum-treated alloy steel
3.2 Forging Drawing—Each forging shall be manufactured
forgings intended for use as turbine rotor disks and wheels.
in accordance with a purchaser-supplied drawing showing the
1.2 The values stated in inch-pound units are to be regarded
finished dimensions and the locations of mechanical test
as standard. The values given in parentheses are mathematical
specimens.
conversions to SI units that are provided for information only
3.3 Supplementary requirements are provided and shall
and are not considered standard.
apply only when specified in the purchaser’s order.
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4. Materials and Manufacture
responsibility of the user of this standard to establish appro-
4.1 Melting Process:
priate safety and health practices and determine the applica-
4.1.1 The steel shall be made by the basic electric-furnace
bility of regulatory limitations prior to use.
process.
2. Referenced Documents 4.1.2 Provisions for subsequent secondary melting of the
2
steel by the consumable electrode-electroslag or vacuum-arc
2.1 ASTM Standards:
remelting processes are included in Supplementary Require-
A 275/A 275M Practice for Magnetic Particle Examination
ment S4.
of Steel Forgings
4.2 Vacuum Treatment—The vacuum degassing require-
A 370 Test Methods and Definitions for MechanicalTesting
ments of Specification A 788/A 788M are mandatory.
of Steel Products
4.2.1 The molten steel shall be vacuum treated prior to or
A 388/A 388M Practice for Ultrasonic Examination of
during the pouring of the ingot in order to remove objection-
Heavy Steel Forgings
able gases, particularly hydrogen.
A 788/A 788M Specification for Steel Forgings, General
4
4.2.1.1 When the vacuum stream degassing process is
Requirements
used,thevacuumsystemmustbeofsufficientcapacitytoeffect
E30 Test Methods for Chemical Analysis of Steel, Cast
3
a blank-off pressure low enough (usually less than 1000 µm) to
Iron, Open-Hearth Iron, and Wrought Iron
break up the normal tight, rope-like stream of molten metal
E 139 Test Methods for Conducting Creep, Creep-Rupture,
into a wide-angled conical stream of relatively small droplets.
and Stress-Rupture Tests of Metallic Materials
The capacity of the system must also be sufficiently high to
3. Ordering Information
reduce the initial surge pressure at the start of the pour to a low
level within 2 min.
3.1 In addition to the ordering information required by
4
4.2.1.2 When the vacuum-lift process is utilized, the mol-
Specification A 788/A 788M, the purchaser shall include with
tenmetalshallberepeatedlydrawnintotheevacuatedvesselto
the inquiry and order, the class of steel, alternative maximum
give a recirculation factor (Note 1) of at least 2.5 to ensure
for silicon content (see Table 1), the choice of yield strength
thorough degassing and mixing of the entire heat. The evacu-
ation system shall be capable of reducing the pressure surges,
which occur each time a new portion of steel is admitted to the
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel,
vessel, to increasingly lower levels until a blank-off pressure
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
(usually less than 1000 µm) is achieved.
A01.06 on Steel Forgings and Billets.
Current edition approved Oct. 1, 2008. Published October 2008. Originally
NOTE 1—The recirculation factor is obtained as follows:
approved in 1962. Last previous edition approved in 2006 as A 471 – 06.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
4
Standards volume information, refer to the standard’s Document Summary page on Details of the vacuum stream degassing process may be found in the Journal
the ASTM website. of the Iron and Steel Institute, Vol 191, January 1959; “Vacuum Pouring of Ingots
3
Withdrawn. for Heavy Forgings” by J. H. Stoll.
*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.
1

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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:A 471–06 Designation: A 471 – 08
Standard Specification for
Vacuum-Treated Alloy Steel Forgings for Turbine Rotor
1
Disks and Wheels
This standard is issued under the fixed designation A 471; 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*
1.1 This specification covers vacuum-treated alloy steel forgings intended for use as turbine rotor disks and wheels.
1.2
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
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 and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
A 275/A 275M Practice for Magnetic Particle Examination of Steel Forgings
A 370 Test Methods and Definitions for Mechanical Testing of Steel Products
A 388/A 388M Practice for Ultrasonic Examination of Heavy Steel Forgings
A 788/A 788M Specification for Steel Forgings, General Requirements
3
E 30 Test Methods for Chemical Analysis of Steel, Cast Iron, Open-Hearth Iron, and Wrought Iron
E 139 Test Methods for Conducting Creep, Creep-Rupture, and Stress-Rupture Tests of Metallic Materials
3. Ordering Information
3.1The purchaser shall specify in the inquiry and order the class of steel desired and test and purchase options (see 4.5.5, 5.2.2,
6.1, 6.3, 7, and 15.1). Ordering Information
3.1 InadditiontotheorderinginformationrequiredbySpecificationA 788/A 788M,thepurchasershallincludewiththeinquiry
and order, the class of steel, alternative maximum for silicon content (see Table 1), the choice of yield strength offset (0.2 or 0.02
%), and any tests, supplementary requirements, and purchase options desired.
3.2 Forging Drawing—Each forging shall be manufactured in accordance with a purchaser-supplied drawing showing the
finished dimensions and the locations of mechanical test specimens.
3.3 Supplementary requirements are provided and shall apply only when specified in the purchaser’s order.
4. Materials and Manufacture
4.1 Melting Process:
4.1.1 The steel shall be made by the basic electric-furnace process.
4.1.2 Provisionsforsubsequentsecondarymeltingofthesteelbytheconsumableelectrode-electroslagorvacuum-arcremelting
processes are included in Supplementary Requirement S4.
4.2 Vacuum Treatment— The vacuum degassing requirements of Specification A 788/A 788Mare mandatory.
4.2.1 Themoltensteelshallbevacuumtreatedpriortoorduringthepouringoftheingotinordertoremoveobjectionablegases,
particularly hydrogen.
1
This specification is under the jurisdiction ofASTM CommitteeA01 on Steel, Stainless Steel and RelatedAlloys,Alloys and is the direct responsibility of Subcommittee
A01.06 on Steel Forgings and Billets.
Current edition approved June 15, 2006.Oct. 1, 2008. Published June 2006.October 2008. Originally approved in 1962. Last previous edition approved in 20052006 as
A 471 – 056.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at [e-mail]. ForAnnualBookofASTMStandards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
Withdrawn.
*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.
1

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A 471–08
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
Silicon 0.15–0.35 0.20 min 0.15–0.35 0.15–0.35
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
CCCC
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
...