ASTM A471-06
(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 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.
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Standards Content (Sample)
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Designation: A 471 – 06
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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope* 3.2 Forging Drawing—Each forging shall be manufactured
in accordance with a purchaser-supplied drawing showing the
1.1 This specification covers vacuum-treated alloy steel
finished dimensions and the locations of mechanical test
forgings intended for use as turbine rotor disks and wheels.
specimens.
1.2 The values stated in inch-pound units are to be regarded
3.3 Supplementary requirements are provided and shall
as standard. The values given in parentheses are mathematical
apply only when specified in the purchaser’s order.
conversions to SI units that are provided for information only
and are not considered standard.
4. Materials and Manufacture
1.3 This standard does not purport to address all of the
4.1 Melting Process:
safety concerns, if any, associated with its use. It is the
4.1.1 The steel shall be made by the basic electric-furnace
responsibility of the user of this standard to establish appro-
process.
priate safety and health practices and determine the applica-
4.1.2 Provisions for subsequent secondary melting of the
bility of regulatory limitations prior to use.
steel by the consumable electrode-electroslag or vacuum-arc
2. Referenced Documents remelting processes are included in Supplementary Require-
2
ment S4.
2.1 ASTM Standards:
4.2 Vacuum Treatment—The vacuum degassing require-
A 275/A 275M Test Method for Magnetic Particle Exami-
ments of Specification A 788/A 788M are mandatory.
nation of Steel Forgings
4.2.1 The molten steel shall be vacuum treated prior to or
A 370 Test Methods and Definitions for MechanicalTesting
during the pouring of the ingot in order to remove objection-
of Steel Products
able gases, particularly hydrogen.
A 388/A 388M Practice for Ultrasonic Examination of
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4.2.1.1 When the vacuum stream degassing process is
Heavy Steel Forgings
used,thevacuumsystemmustbeofsufficientcapacitytoeffect
A 788/A 788M Specification for Steel Forgings, General
a blank-off pressure low enough (usually less than 1000 µm) to
Requirements
break up the normal tight, rope-like stream of molten metal
E30 Test Methods for Chemical Analysis of Steel, Cast
3
into a wide-angled conical stream of relatively small droplets.
Iron, Open-Hearth Iron, and Wrought Iron
The capacity of the system must also be sufficiently high to
E 139 Test Methods for Conducting Creep, Creep-Rupture,
reduce the initial surge pressure at the start of the pour to a low
and Stress-Rupture Tests of Metallic Materials
level within 2 min.
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3. Ordering Information
4.2.1.2 When the vacuum-lift process is utilized, the mol-
tenmetalshallberepeatedlydrawnintotheevacuatedvesselto
3.1 The purchaser shall specify in the inquiry and order the
give a recirculation factor (Note 1) of at least 2.5 to ensure
class of steel desired and test and purchase options (see 4.5.5,
thorough degassing and mixing of the entire heat. The evacu-
5.2.2, 6.1, 6.3, 7, and 15.1).
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 RelatedAlloys, and is the direct responsibility of Subcommittee
(usually less than 1000 µm) is achieved.
A01.06 on Steel Forgings and Billets.
Current edition approved June 15, 2006. Published June 2006. Originally
NOTE 1—The recirculation factor is obtained as follows:
approved in 1962. Last previous edition approved in 2005 as A 471 – 05.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. 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.
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A 471–06
tons of steel lifted per cycle 3 number of cycles
4.5.4 Tempering Temperature—The forgings shall be tem-
heat weight in tons
...
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