ASTM A768/A768M-05(2015)
(Specification)Standard Specification for Vacuum-Treated 12% Chromium Alloy Steel Forgings for Turbine Rotors and Shafts (Withdrawn 2018)
Standard Specification for Vacuum-Treated 12% Chromium Alloy Steel Forgings for Turbine Rotors and Shafts (Withdrawn 2018)
ABSTRACT
This specification covers vacuum-treated 12% chromium alloy steel forgings for turbine rotors and shafts. Materials shall be manufactured by specified melting processes, heat treatment (quenching, tempering, and austenitizing), rough machining, boring, and stress relieving. Product analysis shall be used to evaluate if the elemental chemical compositions of the forgings are within specified range. Specimens shall also undergo tension and impact tests to evaluate their conformance to tensile and notch toughness requirements, which include tensile strength, yield strength, elongation, and reduction of area. Nondestructive tests, such as ultrasonic and internal inspection, and stability tests shall be performed as well. Forgings may be retreated one or more times, but not exceeding three additional times, if the results of mechanical tests fail to meet required values.
SCOPE
1.1 This specification covers vacuum-treated 12 % chromium steel forgings for turbine rotors and shafts.
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 may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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.
WITHDRAWN RATIONALE
This specification covers vacuum-treated 12 % chromium steel forgings for turbine rotors and shafts.
Formerly under the jurisdiction of Committee A01 on Steel, Stainless Steel, and Related Alloys, this specification was withdrawn in May 2018. This standard is being withdrawn without replacement due to its limited use by industry.
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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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: A768/A768M −05 (Reapproved 2015)
Standard Specification for
Vacuum-Treated 12 % Chromium Alloy Steel Forgings for
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Turbine Rotors and Shafts
This standard is issued under the fixed designationA768/A768M; 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 the inquiry and order a detailed drawing, sketch, or written
description of the forging, including the mechanical test
1.1 This specification covers vacuum-treated 12 % chro-
specimen location.
mium steel forgings for turbine rotors and shafts.
1.2 The values stated in either SI units or inch-pound units
4. General Requirements
are to be regarded separately as standard. The values stated in
4.1 Material supplied to this specification shall conform to
each system may not be exact equivalents; therefore, each
the requirements of Specification A788/A788M which outlines
system shall be used independently of the other. Combining
additional ordering information, manufacturing requirements,
values from the two systems may result in non-conformance
testing and retesting methods and procedures, marking,
with the standard.
certification,productanalysisvariations,andadditionalsupple-
1.3 This standard does not purport to address all of the
mentary requirements.
safety concerns, if any, associated with its use. It is the
4.2 If the requirements of this specification are in conflict
responsibility of the user of this standard to establish appro-
with the requirements of Specification A788/A788M, the
priate safety and health practices and determine the applica-
requirements of this specification shall prevail.
bility of regulatory limitations prior to use.
5. Manufacture
2. Referenced Documents
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5.1 The melting processes of Specification A788/A788M
2.1 ASTM Standards:
shall be applicable except that the open-hearth or basic oxygen
A275/A275M Practice for Magnetic Particle Examination of
methods of primary melting shall not be used, and the molten
Steel Forgings
steelshallbevacuumdegassedpriortoorduringpouringofthe
A370 Test Methods and Definitions for Mechanical Testing
ingot.
of Steel Products
5.1.1 If the ESR process is used, then the electrodes shall
A418/A418M Practice for Ultrasonic Examination of Tur-
have been produced from vacuum degassed primary heat(s).
bine and Generator Steel Rotor Forgings
A472/A472M Specification for Heat Stability of Steam Tur-
5.2 In addition to the requirements of Specification A788/
bine Shafts and Rotor Forgings
A788M, it is important to maintain the axial center of the
A788/A788M Specification for Steel Forgings, General Re-
forging in common with the axial center of the original ingot.
quirements
5.3 Heat Treatment:
5.3.1 The heat treatment for mechanical properties shall
3. Ordering Information
consist of quenching and tempering.
3.1 In addition to the ordering information required by
5.3.1.1 The preliminary heat treatment shall consist of
Specification A788/A788M, the purchaser shall include with
normalizing well above the transformation temperature range.
This operation may be performed before preliminary machin-
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This specification is under the jurisdiction of ASTM Committee A01 on Steel,
ing (see 5.4.1).
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee
5.3.1.2 The quenching treatment shall be from above the
A01.06 on Steel Forgings and Billets.
transformation range but below the normalizing temperature
Current edition approved March 1, 2015. Published March 2015. Originally
described in 5.3.1.1. This treatment shall be performed after
approved in 1979. Last previous edition approved in 2010 as A768/A768M – 05
(2010). DOI: 10.1520/A0768_A0768M-05R15.
preliminary machining (see 5.4.1). Austenitizing temperatures
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
shall be in accordance with Table 1.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.3.1.3 The final tempering temperature shall be in accor-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. dance with Table 1.
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A768/A768M − 05 (2015)
TABLE 1 Heat Treating Temperature, °F [°C], Requirements
5.4.4 Machining to Purchaser’s Requirements for
Grade Austenitizing 1st 2nd Shipment—The forging as shipped shall conform to the finish
Tempering, Tempering
and dimension requirements
...
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