ASTM A646/A646M-17

Standard Specification for Premium Quality Alloy Steel Blooms and Billets for Aircraft and Aerospace Forgings

ABSTRACT
This specification deals with the standard requirements for premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into aircraft and aerospace critical parts such as landing-gear forgings. Covered here are three basic classifications of steel, namely: Class I, steel manufactured by vacuum-induction melting or consumable-electrode vacuum melting process; Class II, air-melted steel manufactured by electric-furnace vacuum degassing process; Class III, air-melted steel manufactured by electric-furnace ladle refining and vacuum degassing processes. Steel materials shall be heat-treated and hot-worked by either hot rolling or forging. Alloy steels shall be examined by heat and product analyses and hardenability tests, and shall conform to chemical composition and maximum annealed Brinell hardness requirements. Quality evaluation tests, such as macrotech, microcleanliness, and nondestructive ultrasonic (both immersion and contact examination) inspection, shall be performed as well.
SCOPE
1.1 This specification covers premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into critical parts such as aircraft landing-gear forgings.  
1.2 Blooms and billets, hereinafter referred to as blooms, are semifinished steel products, hot rolled or forged to approximate cross-sectional dimensions. Blooms may be square, round, hexagonal, octagonal, or rectangular in section. For the purposes of this specification, minimum bloom section size will be 16 in.2 [103 cm2].  
1.3 This specification covers two basic classifications of steel:  
1.3.1 Class I—Vacuum-induction melted or consumable-electrode vacuum melted, or other suitable processes which will satisfy the quality requirements of this specification.  
1.3.2 Class II—Air-melted vacuum degassed.  
1.3.3 Class III—Air melted electric furnace ladle refined and vacuum degassed.  
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standards. Within the text and tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.  
1.5 Unless the order specifies the applicable “M” specification the material shall be furnished to the inch-pound units.  
1.6 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

• Status: Historical
• Publication Date: 14-Nov-2017
• ICS: 49.025.10 - Steels
• Technical Committee: A01 - Steel, Stainless Steel and Related Alloys
• Drafting Committee: A01.06 - Steel Forgings and Billets

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:A646/A646M −17
Standard Specification for
Premium Quality Alloy Steel Blooms and Billets for Aircraft
1
and Aerospace Forgings
This standard is issued under the fixed designationA646/A646M; 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* 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This specification covers premium quality alloy steel
A255 Test Methods for Determining Hardenability of Steel
semifinished rolled or forged blooms and billets for reforging
A388/A388M Practice for Ultrasonic Examination of Steel
into critical parts such as aircraft landing-gear forgings.
Forgings
1.2 Blooms and billets, hereinafter referred to as blooms,
A788/A788M Specification for Steel Forgings, General Re-
are semifinished steel products, hot rolled or forged to approxi-
quirements
mate cross-sectional dimensions. Blooms may be square,
A604/A604M Practice for Macroetch Testing of Consum-
round, hexagonal, octagonal, or rectangular in section. For the
able Electrode Remelted Steel Bars and Billets
purposes of this specification, minimum bloom section size
E45 Test Methods for Determining the Inclusion Content of
2 2
will be 16 in. [103 cm ].
Steel
1.3 This specification covers two basic classifications of
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam
steel:
Contact Testing
1.3.1 Class I—Vacuum-induction melted or consumable- E214 Practice for Immersed Ultrasonic Testing by the Re-
electrode vacuum melted, or other suitable processes which
flection Method Using Pulsed Longitudinal Waves (With-
3
will satisfy the quality requirements of this specification. drawn 2007)
1.3.2 Class II—Air-melted vacuum degassed. E381 Method of Macroetch Testing Steel Bars, Billets,
Blooms, and Forgings
1.3.3 Class III—Air melted electric furnace ladle refined
E428 Practice for Fabrication and Control of Metal, Other
and vacuum degassed.
than Aluminum, Reference Blocks Used in Ultrasonic
1.4 The values stated in either inch-pound or SI (metric)
Testing
units are to be regarded separately as standards.Within the text
4
2.2 AMS Standards:
andtables,theSIunitsareshowninbrackets.Thevaluesstated
AMS 2300 Steel Cleanliness, Premium-Quality
in each system are not exact equivalents; therefore, each
AMS 2301 Steel Cleanliness, Aircraft-Quality
system shall be used independently of the other. Combining
AMS 2304 Steel Cleanliness, Special Aircraft-Quality
values from the two systems may result in nonconformance
with the specification.
3. Terminology
1.5 Unless the order specifies the applicable “M” specifica-
3.1 In addition to the terminology requirements of Specifi-
tion the material shall be furnished to the inch-pound units.
cation A788/A788M, the following terms that are specific to
this specification apply:
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.2 Definitions:
ization established in the Decision on Principles for the
3.2.1 air-melted vacuum-degassed steel—arc- or induction-
Development of International Standards, Guides and Recom-
furnace-melted steel that is vacuum treated immediately prior
mendations issued by the World Trade Organization Technical
to or during the operation of pouring the ingot.
Barriers to Trade (TBT) Committee.
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
1
This specification is under the jurisdiction of ASTM Committee A01 on Steel, Standards volume information, refer to the standard’s Document Summary page on
Stainless Steel and Related Alloys and is the direct responsibility of Subcommittee the ASTM website.
3
A01.06 on Steel Forgings and Billets. The last approved version of this historical standard is referenced on
Current edition approved Nov. 15, 2017. Published December 2017. Originally www.astm.org.
4
approved in 1971. Last previous edition approved in 2016 as A646/A646M – 06 Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
(2016). DOI: 10.1520/A0646_A0646M-17. PA 15096, http://www.sae.org.
*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

---------------------- Page: 1 ----------------------
A646/A646M−17
3.2.2 consumable-electrode vacuum-remelted steel—metal 5.1.1 The steel making provisions of Specification A788/
that has been remelted into a crucible in vacuum from single or A788M shall apply, except for the following modifications;
multiple electrodes.
5.
...

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: A646/A646M − 06 (Reapproved 2016) A646/A646M − 17
Standard Specification for
Premium Quality Alloy Steel Blooms and Billets for Aircraft
1
and Aerospace Forgings
This standard is issued under the fixed designation A646/A646M; 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 premium quality alloy steel semifinished rolled or forged blooms and billets for reforging into
critical parts such as aircraft landing-gear forgings.
1.2 Blooms and billets, hereinafter referred to as blooms, are semifinished steel products, hot rolled or forged to approximate
cross-sectional dimensions. Blooms may be square, round, hexagonal, octagonal, or rectangular in section. For the purposes of this
2 2
specification, minimum bloom section size will be 16 in. [103 cm ].
1.3 This specification covers two basic classifications of steel:
1.3.1 Class I—Vacuum-induction melted or consumable-electrode vacuum melted, or other suitable processes which will satisfy
the quality requirements of this specification.
1.3.2 Class II—Air-melted vacuum degassed.
1.3.3 Class III—Air melted electric furnace ladle refined and vacuum degassed.
1.4 The values stated in either inch-pound or SI (metric) units are to be regarded separately as standards. Within the text and
tables, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system shall
be used independently of the other. Combining values from the two systems may result in nonconformance with the specification.
1.5 Unless the order specifies the applicable “M” specification the material shall be furnished to the inch-pound units.
1.6 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
2.1 ASTM Standards:
A255 Test Methods for Determining Hardenability of Steel
A388/A388M Practice for Ultrasonic Examination of Steel Forgings
A788/A788M Specification for Steel Forgings, General Requirements
A604/A604M Practice for Macroetch Testing of Consumable Electrode Remelted Steel Bars and Billets
E45 Test Methods for Determining the Inclusion Content of Steel
E114 Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing
E127 Practice for Fabrication and Control of Aluminum Alloy Ultrasonic Standard Reference Blocks
3
E214 Practice for Immersed Ultrasonic Testing by the Reflection Method Using Pulsed Longitudinal Waves (Withdrawn 2007)
E381 Method of Macroetch Testing Steel Bars, Billets, Blooms, and Forgings
E428 Practice for Fabrication and Control of Metal, Other than Aluminum, Reference Blocks Used in Ultrasonic Testing
4
2.2 AMS Standards:
AMS 2300 Steel Cleanliness, Premium-Quality
AMS 2301 Steel Cleanliness, Aircraft-Quality
1
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 March 1, 2016Nov. 15, 2017. Published April 2016December 2017. Originally approved in 1971. Last previous edition approved in 20112016
as A646/A646M – 06 (2011).(2016). DOI: 10.1520/A0646_A0646M-06R16.10.1520/A0646_A0646M-17.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3
The last approved version of this historical standard is referenced on www.astm.org.
4
Available from SAE International (SAE), 400 Commonwealth Dr., Warrendale, PA 15096, http://www.sae.org.
*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

---------------------- Page: 1 ----------------------
A646/A646M − 17
AMS 2304 Steel Cleanliness, Special Aircraft-Quality
3. Terminology
3.1 In addition to the terminology requirements of Specification A788/A788M, the following terms that are specific t
...