ASTM_A_646_-_A_646M_-_17.pdf

Designation:A646/A646M17Standard Specification forPremium Quality Alloy Steel Blooms and Billets for Aircraftand Aerospace Forgings1This standard is issued under the fixed designation A646/A646M;the number immediately following the designation indicates the yearof 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 steelsemifinished rolled or forged blooms and billets for reforginginto 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 approxi-mate cross-sectional dimensions.Blooms may be square,round,hexagonal,octagonal,or rectangular in section.For thepurposes of this specification,minimum bloom section sizewill be 16 in.2103 cm2.1.3 This specification covers two basic classifications ofsteel:1.3.1 Class IVacuum-induction melted or consumable-electrode vacuum melted,or other suitable processes whichwill satisfy the quality requirements of this specification.1.3.2 Class IIAir-melted vacuum degassed.1.3.3 Class IIIAir melted electric furnace ladle refinedand vacuum degassed.1.4 The values stated in either inch-pound or SI(metric)units are to be regarded separately as standards.Within the textand tables,the SI units are shown in brackets.The values statedin each system are not exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in nonconformancewith the specification.1.5 Unless the order specifies the applicable“M”specifica-tion the material shall be furnished to the inch-pound units.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2A255 Test Methods for Determining Hardenability of SteelA388/A388M Practice for Ultrasonic Examination of SteelForgingsA788/A788M Specification for Steel Forgings,General Re-quirementsA604/A604M Practice for Macroetch Testing of Consum-able Electrode Remelted Steel Bars and BilletsE45 Test Methods for Determining the Inclusion Content ofSteelE114 Practice for Ultrasonic Pulse-Echo Straight-BeamContact TestingE214 Practice for Immersed Ultrasonic Testing by the Re-flection Method Using Pulsed Longitudinal Waves(With-drawn 2007)3E381 Method of Macroetch Testing Steel Bars,Billets,Blooms,and ForgingsE428 Practice for Fabrication and Control of Metal,Otherthan Aluminum,Reference Blocks Used in UltrasonicTesting2.2 AMS Standards:4AMS 2300 Steel Cleanliness,Premium-QualityAMS 2301 Steel Cleanliness,Aircraft-QualityAMS 2304 Steel Cleanliness,Special Aircraft-Quality3.Terminology3.1 In addition to the terminology requirements of Specifi-cation A788/A788M,the following terms that are specific tothis specification apply:3.2 Definitions:3.2.1 air-melted vacuum-degassed steelarc-or induction-furnace-melted steel that is vacuum treated immediately priorto or during the operation of pouring the ingot.1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition approved Nov.15,2017.Published December 2017.Originallyapproved in 1971.Last previous edition approved in 2016 as A646/A646M 06(2016).DOI:10.1520/A0646_A0646M-17.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available 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 standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 3.2.2 consumable-electrode vacuum-remelted steelmetalthat has been remelted into a crucible in vacuum from single ormultiple electrodes.3.2.3 electroslag-melted steelmetal that has been remeltedinto a crucible from single or multiple electrodes utilizing anelectrical discharge through molten slag as a source of heat.3.2.