1、Designation: A 646/A 646M 06Standard Specification forPremium Quality Alloy Steel Blooms and Billets for Aircraftand Aerospace Forgings1This standard is issued under the fixed designation A 646/A 646M; the number immediately following the designation indicates the yearof original adoption or, in the
2、 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*1.1 This specification covers premium quality alloy steelsemifinished rolled or forged bl
3、ooms 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 re
4、ctangular 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
5、quality requirements of this specification.1.3.2 Class IIAir-melted vacuum degassed.1.3.3 Class IIIAir melted electric furnace ladle refinedand vacuum degassed1.4 The values stated in either inch-pound or SI (metric)units are to be regarded separately as standards. Within the textand tables, the SI
6、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-
7、tion the material shall be furnished to the inch-pound units.2. Referenced Documents2.1 ASTM Standards:2A 255 Test Methods for Determining Hardenability of SteelA 388/A 388M Practice for Ultrasonic Examination ofHeavy Steel ForgingsA 788/A 788M Specification for Steel Forgings, GeneralRequirementsA
8、604 Test Method for Macroetch Testing of ConsumableElectrode Remelted Steel Bars and BilletsE45 Test Methods for Determining the Inclusion Contentof SteelE114 Practice for Ultrasonic Pulse-Echo Straight-BeamExamination by the Contact MethodE 127 Practice for Fabricating and Checking AluminumAlloy Ul
9、trasonic Standard Reference BlocksE 214 Practice for Immersed Ultrasonic Testing by theReflection Method Using Pulsed Longitudinal WavesE 381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and Forgings2.2 AMS Standards:3AMS 2300 Steel Cleanliness, Premium-QualityAMS 2301 Steel Cleanliness,
10、Aircraft-QualityAMS 2304 Steel Cleanliness, Special Aircraft-Quality3. Terminology3.1 In addition to the terminology requirements of Specifi-cation A 788/A 788M, the following terms that are specific tothis specification apply:3.2 Definitions:3.2.1 air-melted vacuum-degassed steelarc- or induction-f
11、urnace-melted steel that is vacuum treated immediately priorto or during the operation of pouring the ingot.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 re-mel
12、ted into a crucible from single or multiple electrodesutilizing an electrical discharge through molten slag as a sourceof heat.3.2.3.1 DiscussionFor the purposes of this specificationthe parent heat from which any electrode for remelting by theelectroslag process has been produced shall have been ei
13、thermelted under vacuum or vacuum degassed immediately priorto or during pouring of the heat.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 ed
14、ition approved Dec. 1, 2006. Published January 2007. Originallyapproved in 1971. Last previous edition approved in 2004 as A 646/A 646M 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
15、 information, refer to the standards Document Summary page onthe ASTM website.3Available from Society of Automotive Engineers, 400 Commonwealth Drive,Warrendale, PA 15096.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C7
16、00, West Conshohocken, PA 19428-2959, United States.3.2.4 vacuum induction melted steelmetal that has beenmelted, 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 requ
17、irements of Specification A 788/A 788M, which out-lines additional ordering information, manufacturing require-ments, testing and retesting methods and procedures, marking,certification, product analysis variations, and additional supple-mentary requirements.4.1.1 If the requirements of this specifi
18、cation are in conflictwith the requirements of Specification A 788/A 788M, therequirements of this specification shall prevail.4.2 In addition to the ordering requirements of SpecificationA 788/A 788M, the following information should be suppliedby the purchaser:4.2.1 Class designation (see 1.3),4.2
19、.2 Quality level (Table 2), grade designation (Table 1), ordetailed chemistry for nonstandard grades,4.2.3 Desired billet 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
20、.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 Specific ultrasonic examination requirements, such astransducer type and size, whether contact or immersion pre-ferred, level of reportable discontinuities and any specialsurface fi
21、nish requirements.4.2.10 Hardenability standards of acceptance (see 8.1), and4.2.11 Any supplementary requirements desired.5. Manufacture5.1 Melting Practice:5.1.1 The steel making provisions of Specification A 788/A 788M shall apply, except for the following modifications;5.1.1.1 Class I material s
22、hall be manufactured by thevacuum-induction-melting process or by the consumable-electrode vacuum-melting (VAR) process. By 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-d
23、egassed process.5.1.1.3 Class III material shall be manufactured by theelectric furnace process with ladle refining and vacuum 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
24、 made from air-melt ingotsshall have at least 2 to 1 reduction of area from ingot to bloom.On blooms exceeding 225 in.21450 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
25、 all material purchased tothis specification will be furnished in the as forged or rolled(untreated) condition. In this condition 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
26、maximum Brinell Hardness,as specified in Table 2 or by agreement.5.3.3 Material shall be furnished in condition to withstand,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 befo
27、reshipment shall be optional with the manufacturer, who shall beresponsible (in the same manner as for discontinuities dis-closed after delivery) for cracks which may develop beforematerial is subjected to reheating. When a specific heattreatment or conditioning of material is specified by thepurcha
28、ser, the manufacturer shall be responsible only forcarrying out those specific operations and not for any crackingthat may subsequently develop.6. Chemical Requirements Chemical Requirements6.1 General Requirements:6.1.1 Table 1 lists standard grades of alloy steel that arecurrently produced in prem
29、ium quality; however, it is not theintent of this specification to restrict application only to thematerials listed in Table 1.6.1.2 When a standard grade is ordered, the analysis shallconform to the requirements as to chemical compositionprescribed in Table 1 for the ordered grade.6.1.3 The steel,
30、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 from sampling in accor-dance with Specification A 788/A 788M shall comply withTable 1 for standard grades, or to the requirements of the order.6.3 Product
31、Analysis:6.3.1 The purchaser may use the product analysis provisionof Specification A 788/A 788M to obtain a product analysisfrom a billet or bloom representing each heat or multiple heat.7. Quality Evaluation Tests7.1 MacroetchMacroetch inspection shall be required forall material furnished to this
32、 specification. Samples represent-ing the top and bottom of each ingot shall be examined.Macroetching shall be performed in accordance with MethodE 381 and Test Method A 604, as applicable. Standards ofacceptance shall be specified by the purchaser in the order.7.2 MicrocleanlinessAll material furni
33、shed to this speci-fication shall be inspected for microcleanliness. At least onesample shall be removed from a location midway between theTABLE 1 Maximum Permissible Discontinuities in UltrasonicExaminationQualityLevelResponse,in. mmStringers,Length in. mmSingleDiscontinuitiesMultipleDiscontinuitie
34、sAA364 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 3.025A 646/A 646M 062center and 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 produ
35、ced fromcontinually cast material the samples shall represent thebeginning and end of each strand produced from the heat. Thespecimens shall be prepared and rated by the proceduredescribed in MethodAof Test Methods E45. The polished faceshall be longitudinal to the direction of maximum hot working.A
36、ll specimens shall be prepared and rated in accordance withTest Methods E45, using Method D (Modified JK Chart) forClass I steel and Method A (JK Chart) for Classrs II and IIIsteel. Standards of acceptance shall be specified by the pur-chaser in the order.7.3 Nondestructive Testing, Ultrasonic Inspe
37、ction:7.3.1 General:7.3.1.1 All material ordered to this specification shall besubjected to ultrasonic examination. Inspection may be 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
38、 chosen method.7.3.1.2 The usage of reference blocks containing flat-bottomed holes for calibration is the preferred method forevaluation of discontinunity size up to billet cross-sectionaldimensions of approximately 12 in. 300 mm. With largersizes, it is recognized that reference block fabrication
39、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 Immersion Examination ProcedureThis method isrecommended for material where the cross-sectional dimensionto be inspected is less than approximately 8 in. 200 mm.Materia
40、l inspected by the immersion method shall be per-formed in accordance with the procedure outlined in PracticeE 214.7.3.3 Contact Examination ProcedureMaterial inspectedby the contact method shall be performed in accordance withthe procedure outlined in Practice E114 or Practice A 388/A 388M.7.3.4 Sc
41、anningBlooms shall be examined using thestraight-beam (longitudinal-wave) technique. Blooms havingparallel surfaces shall be scanned from two adjacent sides,excluding ends. Cylindrical blooms shall be scanned a mini-mum of 180 around the circumference, with the beam directedalong the radius, noting
42、that an axial scan from the end faces isnot normally applicable.7.3.5 Quality Levels and Reference Standards:7.3.5.1 The reference blocks shall be fabricated in accor-dance with the procedures of Practice E 127, with the excep-tion of surface finish. Transducer contact surfaces of theproduct and the
43、 reference block should be comparable rough-ness. Flatbottom hole sizes shall be in accord with theapplicable quality level specified in Table 2.7.3.5.2 A comparison of the back reflections betweenequivalent thicknesses of the reference block material and theactual material to be tested, without cha
44、nge in instrumentTABLE 2 Chemical and Hardness RequirementsAComposition, %Proprie-tary NameorGradeGradeNo.Carbon Manga-nesePhos-phorusSulfur Silicon Nickel Chro-miumMolyb-denumVana-diumOthers MaximumAnnealedBrinellHardness3310 1 0.080.13 0.450.60 0.015max 0.012 max 0.200.35 3.253.75 1.401.75 . . . .
45、 . . . . . 2629310 2 0.080.13 0.450.65 0.015 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 . . . . . . 22943
46、30 Mod. 5 0.280.33 0.751.00 0.015 max 0.012 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 . . . . . . 2
47、85300 M 8 0.380.43 0.650.90 0.012 max 0.012 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 . . . 23541
48、30 11 0.280.33 0.400.60 0.015 max 0.012 max 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, 285Boron6
49、150 14 0.480.53 0.700.90 0.015 max 0.012 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 max 0.10 max 7.08.0 0.901.10 0.901.10 0.060.12 Co 4.254.75 341Marage20018
