1、Designation: A646/A646M 17Standard 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 cas
2、e 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
3、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 rectang
4、ular 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 quali
5、ty 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 unit
6、s 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
7、 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 is
8、sued 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-qu
9、irementsA604/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
10、 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-
11、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-
12、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 Subcommitte
13、eA01.06 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, orconta
14、ct 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 Commonwea
15、lth 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 international
16、ly 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.1Mon Apr 30 53 3.2.2 consumable-electrode vacuum-remelted
17、 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.3.2.3.1 DiscussionFor th
18、e purposes of this specificationthe parent heat from which any electrode for remelting by theelectroslag process has been produced shall have been eithermelted under vacuum or vacuum degassed immediately priorto or during pouring of the heat.3.2.4 vacuum induction melted steelmetal that has beenmelt
19、ed, refined, and poured from an induction furnace operat-ing under vacuum.4. Ordering Information and General Requirements4.1 Material supplied to this specification shall conform tothe requirements of Specification A788/A788M, which out-lines additional ordering information, manufacturingrequiremen
20、ts, testing and retesting methods and procedures,marking, certification, product analysis variations, and addi-tional supplementary requirements.4.1.1 If the requirements of this specification are in conflictwith the requirements of Specification A788/A788M, therequirements of this specification sha
21、ll prevail.4.2 In addition to the ordering requirements of SpecificationA788/A788M, the following information should be suppliedby the purchaser:4.2.1 Class designation (see 1.3),4.2.2 Quality level (Table 1), grade designation (Table 2), ordetailed chemistry for nonstandard grades,4.2.3 Desired bil
22、let or bloom size,4.2.4 Weight or quantity and length,4.2.5 Minimum forging reduction required if ordered sizeexceeds 225 in.21450 cm2 (see 5.2.2),4.2.6 Annealing, if required (see 5.3.2),4.2.7 Macroetch standards of acceptance (see 7.1),4.2.8 Microcleanliness standards of acceptance (see 7.2),4.2.9
23、 Specific ultrasonic examination requirements, such astransducer type and size, whether contact or immersionpreferred, level of reportable discontinuities and any specialsurface finish requirements.4.2.10 Hardenability standards of acceptance (see 8.1), and4.2.11 Any supplementary requirements desir
24、ed.5. Manufacture5.1 Melting Practice:5.1.1 The steel making provisions of Specification A788/A788M shall apply, except for the following modifications;5.1.1.1 Class I material shall be manufactured by thevacuum-induction-melting process or by the consumable-electrode vacuum-melting (VAR) process. B
25、y agreement otherprocesses such as electroslag or electron-beam melting may beconsidered acceptable.5.1.1.2 Class II material shall be manufactured by anelectric-furnace vacuum-degassed process.5.1.1.3 Class III material shall be manufactured by theelectric furnace process with ladle refining and va
26、cuum degas-sing.5.2 Hot-Working Procedure:5.2.1 Blooms may be either hot rolled or forged.5.2.2 Blooms having cross-sectional areas ranging from 16to 225 in.2100 to 1450 cm2 when made from air-melt ingotsshall have at least 2 to 1 reduction of area from ingot to bloom.On blooms exceeding 225 in.2145
27、0 cm2 forging reductionrequirements shall be by agreement. Ingot-to-final forgingreduction is not included in this requirement.5.3 Heat Treatment:5.3.1 Unless otherwise specified all material purchased tothis specification will be furnished in the as forged or rolled(untreated) condition. In this co
28、ndition some grades may not besoft enough for cold sawing, and may be prone to cracking.5.3.2 When specified, the material may be ordered annealedor normalized and tempered to a maximum Brinell Hardness,as specified in Table 2 or by agreement.5.3.3 Material shall be furnished in condition to withsta
29、nd,for an indefinite time, exposure to all climatic conditionswithout developing any external or internal cracks. The methodof cooling after hot working or of heat treatment beforeshipment shall be optional with the manufacturer, who shall beresponsible (in the same manner as for discontinuities dis
30、-closed after delivery) for cracks which may develop beforematerial is subjected to reheating. When a specific heattreatment or conditioning of material is specified by thepurchaser, the manufacturer shall be responsible only forcarrying out those specific operations and not for any crackingthat may
31、 subsequently develop.6. Chemical Requirements6.1 General Requirements:6.1.1 Table 2 lists standard grades of alloy steel that arecurrently produced in premium quality; however, it is not theintent of this specification to restrict application only to thematerials listed in Table 2.6.1.2 When a stan
32、dard grade is ordered, the analysis shallconform to the requirements as to chemical compositionprescribed in Table 2 for the ordered grade.6.1.3 The steel, when ordered to other than a standardanalysis, shall conform to the requirements of the order.6.2 Heat Analysis:6.2.1 The heat analysis obtained
33、 from sampling in accor-dance with Specification A788/A788M shall comply withTable 2 for standard grades, or to the requirements of the order.TABLE 1 Maximum Permissible Discontinuities in UltrasonicExaminationQualityLevelResponse,in. mmStringers,Length in. mmSingleDiscontinuitiesMultipleDiscontinui
34、tiesAA364 1.0264 0.8264 12 1.012.0A564 2.0364 1.0364 1 1.025B864 3.0564 2.0564 1 2.025C1264 5.0864 3.0864 1 3.025A646/A646M 172Mon Apr 30 53 6.3 Product Analysis:6.3.1 The purchaser may use the product analysis provisionof Specification A788/A788M to obtain a product analysisfrom a billet or bloom r
35、epresenting each heat or multiple heat.7. Quality Evaluation Tests7.1 MacroetchMacroetch inspection shall be required forall material furnished to this specification. Samples represent-ing the top and bottom of each ingot shall be examined.Macroetching shall be performed in accordance with MethodE38
36、1 and Practice A604/A604M, as applicable. Standards ofacceptance shall be specified by the purchaser in the order.7.2 MicrocleanlinessAll material furnished to this speci-fication shall be inspected for microcleanliness. At least onesample shall be removed from a location midway between thecenter an
37、d outside surface representing the top and bottom ofthe first and last ingots of each heat or from an ingot from eachplate for bottom poured ingots. For blooms produced fromcontinually cast material the samples shall represent thebeginning and end of each strand produced from the heat. Thespecimens
38、shall be prepared and rated by the proceduredescribed in Method A of Test Methods E45. The polished faceshall be longitudinal to the direction of maximum hot working.All specimens shall be prepared and rated in accordance withTest Methods E45, using Method D (Modified JK Chart) forClass I steel and
39、Method A (JK Chart) for Classes II and IIIsteel. Standards of acceptance shall be specified by the pur-chaser in the order.7.3 Nondestructive Testing, Ultrasonic Inspection:7.3.1 General:7.3.1.1 All material ordered to this specification shall besubjected to ultrasonic examination. Inspection may be
40、 per-formed by either the immersion or the contact method provid-ing that the manufacturer can ensure adequate resolution of theapplicable reference standards with the chosen method.7.3.1.2 The usage of reference blocks containing flat-bottomed holes for calibration is the preferred method forevalua
41、tion of discontinuity size up to billet cross-sectionaldimensions of approximately 12 in. 300 mm. With largersizes, it is recognized that reference block fabrication becomesdifficult and in general a back reflection method of calibrationcan be used as an alternative as referenced in 7.3.6.3.7.3.2 Im
42、mersion Examination ProcedureThis method isrecommended for material where the cross-sectional dimensionto be inspected is less than approximately 8 in. 200 mm.Material inspected by the immersion method shall be per-formed in accordance with the procedure outlined in PracticeE214.TABLE 2 Chemical and
43、 Hardness RequirementsAComposition, %ProprietaryName orGradeGradeNo.CarbonManga-nesePhos-phorusSulfur Silicon NickelChro-miumMolyb-denumVana-diumOthersMaximumAnnealedBrinellHardness3310 1 0.080.13 0.450.60 0.015max 0.012 max 0.200.35 3.253.75 1.401.75 . . . . . . . . . 2629310 2 0.080.13 0.450.65 0.
44、015 max 0.012 max 0.200.35 3.003.50 1.001.40 0.080.15 . . . . . . 2624620 3 0.170.22 0.450.65 0.015 max 0.012 max 0.200.35 1.652.00 . . . 0.200.30 . . . . . . 2298620 4 0.180.23 0.700.90 0.015max 0.012 max 0.200.35 0.400.70 0.400.60 0.150.25 . . . . . . 2294330 Mod. 5 0.280.33 0.751.00 0.015 max 0.0
45、12 max 0.200.35 1.652.00 0.700.95 0.350.50 0.050.10 . . . 2854335 Mod. 6 0.330.38 0.600.90 0.015 max 0.012 max 0.400.60 1.652.00 0.650.90 0.300.40 0.170.23 . . . 2854340 7 0.380.43 0.650.85 0.015 max 0.012 max 0.200.35 1.652.00 0.700.90 0.200.30 . . . . . . 285300 M 8 0.380.43 0.650.90 0.012 max 0.0
46、12 max 1.451.80 1.652.00 0.700.95 0.350.45 0.050.10 . . . 285D6AC 9 0.450.50 0.600.90 0.010 max 0.010 max 0.150.30 0.400.70 0.901.20 0.901.10 0.080.15 . . . 285H-11 10 0.380.43 0.200.40 0.015 max 0.015 max 0.801.00 . . . 4.755.25 1.201.40 0.400.60 . . . 2354130 11 0.280.33 0.400.60 0.015 max 0.012 m
47、ax 0.200.35 . . . 0.801.10 0.150.25 . . . . . . 2294140 12 0.380.43 0.751.00 0.015 max 0.012 max 0.200.35 . . . 0.801.10 0.150.25 . . . . . . 23598BV40 13 0.400.46 0.751.00 0.015 max 0.012 max 0.500.80 0.600.90 0.801.05 0.450.60 0.010.06 0.0005 min, 285Boron6150 14 0.480.53 0.700.90 0.015 max 0.012
48、max 0.200.35 . . . 0.801.10 . . . 0.15 min . . . 23552100 15 0.981.10 0.250.45 0.015 max 0.010 max 0.200.35 . . . 1.301.60 . . . . . . . . . 302HP 9-4-20 16 0.170.23 0.200.40 0.010 max 0.010 max 0.10 max 8.59.5 0.650.85 0.901.10 0.060.12 Co 4.254.75 341HP 9-4-30 17 0.290.34 0.100.35 0.010 max 0.010
49、max 0.10 max 7.08.0 0.901.10 0.901.10 0.060.12 Co 4.254.75 341Marage20018 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.019.0 . . . 3.03.50 . . . Co 8.09.0Ti 0.100.25Al 0.050.15B, Zr, Ca added321Marage25019 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 17.019.0 . . . 4.65.2 . . . Co 7.08.5Ti 0.300.50Al 0.050.15B, Zr, Ca added321Marage30020 0.03 max 0.10 max 0.010 max 0.010 max 0.10 max 1
