1、Designation: A668/A668M 131American Association StateHighway and Transportation Officials StandardAASHTO No.: M 102Standard Specification forSteel Forgings, Carbon and Alloy, for General IndustrialUse1This standard is issued under the fixed designation A668/A668M; the number immediately following th
2、e 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.This standard has been approved for
3、use by agencies of the Department of Defense.1NOTESections 6.1 and 7.1.4.3 were editorially corrected in August 2013.1. Scope*1.1 This specification covers untreated and heat-treatedcarbon and alloy steel forgings for general industrial use. OtherASTM specifications for forgings are available for sp
4、ecificapplications such as pressure vessels, railroad use, turbinegenerators, gearing, and others involving special temperaturerequirements.1.2 Hot-rolled or cold finished bars are not within the scopeof this specification.1.3 Six classes of carbon steel and seven classes of alloysteel forgings are
5、listed (see Section 7), which indicates theirrequired heat treatments, as well as mechanical properties.1.4 Provision, with the suffix H for certification andmarking, for the supply of forgings after hardness testing only.1.5 Supplementary requirements, including those in Speci-fication A788/A788M,
6、of an optional nature are provided.These shall apply only when specified by the purchaser.1.6 Appendix X1 lists the current classes corresponding tothe various classes of Specifications A235, A237, and A243,which have been superseded by this specification.1.7 The values stated in either SI units or
7、inch-pound unitsare to be regarded separately as standard; within the text andtables, the SI units are shown in brackets. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in n
8、onconformancewith the standard.1.8 Unless the order specifies the applicable “M“specification, the forgings shall be furnished to the inch-poundunits.2. Referenced Documents2.1 ASTM Standards:2A275/A275M Practice for Magnetic Particle Examination ofSteel ForgingsA370 Test Methods and Definitions for
9、 Mechanical Testingof Steel ProductsA388/A388M Practice for Ultrasonic Examination of SteelForgingsA788/A788M Specification for Steel Forgings, General Re-quirementsE290 Test Methods for Bend Testing of Material for Ductil-ityE381 Method of Macroetch Testing Steel Bars, Billets,Blooms, and Forgings3
10、. Terminology3.1 The terminology section of Specification A788/A788Mis applicable to this specification.3.2 Definitions of Terms Specific to This Standard:3.2.1 classa description of steel forgings based on heattreatment, mechanical properties and composition.3.2.2 controlling cross section thicknes
11、s (TC)the diameterof the largest theoretical sphere which can be inscribed withinthe volume of the forging.3.2.3 TPdesignates prolongations which have a size otherthan the controlling cross section thickness (TC).4. Ordering Information and General Requirements4.1 Material supplied to this specifica
12、tion shall conform tothe requirements of Specification A788/A788M which outlinesadditional ordering information, manufacturing requirements,testing and retesting methods and procedures, marking,1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related A
13、lloys and is the direct responsibility of SubcommitteeA01.06 on Steel Forgings and Billets.Current edition approved June 1, 2013. Published June 2013. Originallyapproved in 1972. Last previous edition approved in 2009 as A668/A668M 04(2009). DOI: 10.1520/A0668_A0668M-13E01.2For referenced ASTM stand
14、ards, 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM Interna
15、tional, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1certification, product analysis variations and additional supple-mentary requirements.4.1.1 If the requirements of this specification are in conflictwith the requirements of Specification A788/A788M, therequi
16、rements of this specification shall prevail.4.2 When this specification is to be applied to an inquiry,contract, or order, the purchaser should furnish the followinginformation:4.2.1 The ordering information required by SpecificationA788/A788M,4.2.2 The class of forging desired as listed in Table 1,
17、4.2.3 Location(s) of areas of significant loading if testspecimens are to be located in accordance with 7.1.4.5,4.2.4 The options which may be selected as found in 5.3.2,6.1, and 7.3, and4.2.5 Any applicable supplementary requirements.5. Materials and Manufacture5.1 DiscardSufficient discard shall b
18、e made from eachingot to secure freedom from piping and undue segregation.5.2 Forging Process:5.2.1 The forging shall be brought as close as practical tofinished shape and size by hot mechanical work.5.2.2 Supplementary requirements S2, S14, and S15 may bespecified by the purchaser to satisfy concer
19、ns about the utilityof the proposed forging.5.3 Heat Treatment:5.3.1 All forgings, other than Class A, shall be heat treated.See Section 7.5.3.2 Where options exist within a class, the choice of heattreatment shall be left to the discretion of the manufacturer,unless the purchaser specifies one of t
20、he available options.6. Chemical Composition6.1 The steel shall conform to the requirements prescribedin Table 1.6.2 The choice of chemical composition is left to thediscretion of the manufacturer, unless otherwise specified bythe purchaser. See Appendix X2.6.3 Heat Analysis:6.3.1 An analysis of eac
21、h heat shall be made by themanufacturer.6.4 Product AnalysisAn analysis may be made by thepurchaser according to the requirements of Specification A788/A788M. If a standard grade has been used to manufacture theforging the permissible variations in composition of Specifi-cation A788/A788M shall appl
22、y. If a non-standard grade ofsteel has been used, and composition limits have not beensupplied, the product analysis can be used only to confirm thetype of steel supplied.7. Mechanical Properties7.1 Tensile Requirements:7.1.1 The material shall conform to the tensile propertiesprescribed in Table 2.
23、 See Test Methods A370.7.1.2 All ForgingsThe dimensions of the controlling crosssection thickness (TC) of the forging at time of heat treatmentdetermine the mechanical properties to be met within eachclass (see Table 2) except as noted in 7.1.4.2.7.1.3 Number of TestsUnless the purchaser specifies t
24、hatforgings shall be furnished in accordance with the requirementsof 7.3, the number of tension tests performed shall be asfollows:7.1.3.1 For all classes of heat-treated forgings with as-heattreated weights (excluding test prolongations) less than 5000 lb2250 kg each, one test shall be made from ea
25、ch sizeclassification represented in each heat in each annealing ornormalizing charge, or from each size classification in eachheat in each normalizing or quenching charge represented ineach tempering charge. For untreated forgings (Class A)weighing less than 5000 lb 2250 kg each, one test from each
26、heat shall be made.7.1.3.2 On all classes, for forgings with as-heat treatedweights (excluding test prolongations) of 5000 lb 2250 kg ormore, at least one test from each forging shall be made.7.1.3.3 On all classes, for forgings with as-heat treatedweights (excluding test prolongations) of 7000 lb 3
27、200 kg ormore, two tests will be taken: on ring and disk forgings 180apart; on shafts and long hollow cylinders (over 80 in. 2.0 min length excluding test material), one from each end and offset180. Shafts and cylinder forgings 80 in. 2.0 m or less inlength (excluding test material) may have both te
28、sts located atone end 180 apart.7.1.3.4 When forgings are made in multiple as a singleforging, that is, forged as one piece and divided after heattreatment, the multiple forging shall be considered as oneforging, and the number of tests required shall be as designatedin 7.1.3.1, 7.1.3.2, and 7.1.3.3
29、.7.1.4 Prolongations:7.1.4.1 A sufficient number of the forgings shall haveprolongations for extracting specimens for testing. Examplesof test locations for various forging configurations are shown inFigs. 1 and 2.NOTE 1Figures provided demonstrate the concept of controlling crosssection thickness (
30、TC) but do not encompass all possible test prolongationconfigurations which meet the requirements of Section 7.7.1.4.2 For all forgings of non-uniform cross section inclasses A, B, C, D, E, G and H: The prolongation(s) may beextensions of sections other than the controlling cross sectionthickness (T
31、C), that is TP TC. In this case, the dimension ofTPshall determine the mechanical properties to be met withineach class. When TP TC,TPshall not have more reductionthan the smallest cross section to be qualified.(1) For annealed, normalized, or normalized and temperedforgings in classes A, B, C, D, E
32、, G and H the center of thegage length axis of tension test specimens shall be14 theTABLE 1 Chemical RequirementsElements Composition, max, %Classes A to Fand AH to FHClasses G to Nand GH to NHManganese 1.35 .Phosphorus 0.050 0.040Sulfur 0.025 0.025A668/A668M 1312controlling cross section thickness
33、(TC) from one surfaceexcept as noted in 7.1.4.2 (2).(2) If the prolongation thickness (TP) is less than thecontrolling cross section thickness (TC) the center of the gagelength axis of the tension test shall be of the prolongationthickness (TP) from one surface.7.1.4.3 For quenched forgings in Class
34、es F, J, K, L, M, andN, the center of the gage length axis of the tension testspecimen shall be at a minimum14 (TC) from one quenchedsurface and 312 in. 90 mm from all other quenched surfaces.7.1.4.4 In place of prolongations, the manufacturer may: (1)elect to submit a representative forging(s) to r
35、epresent each testlot; in this event, the representative forging must be made fromthe same heat of steel, must not receive more reduction than theforging it represents, must receive the same type of hotworking it represents, be of the same controlling cross sectionTABLE 2 Tensile RequirementsA,BClas
36、sControlling CrossSection (TC),in. mmTensile Strength, minYield Point, YieldStrength 0.2 %Offset, minElonga-tionin2in. or50 mm,min, %Reduc-tion ofArea,min, %BrinellHardness(HBW)Over Not Over psi MPa psi MPaCarbon SteelA (AH) (Untreated) . 20 500 47 000 325 . . . . 183 maxB (BH) (Annealed, or normali
37、zed, ornormalized and tempered). 20 500 60 000 415 30 000 205 24 36 120174C (CH) (Annealed, or normalized, or . 12 300 66 000 455 33 000 230 23 36 137183normalized and tempered) 12 300 20 500 66 000 455 33 000 230 22 34 137183D (DH) (Normalized, annealed, or normalized . 8 200 75 000 515 37 500 260
38、24 40 149207and tempered) 8 200 12 300 75 000 515 37 500 260 22 35 14920712 300 20 500 75 000 515 37 500 260 20 32 14920720 500 75 000 515 37 500 260 19 30 149207E (EH) (Normalized and tempered or . 8 200 85 000 585 44 000 305 25 40 174217double-normalized and tempered) 8 200 12 300 83 000 570 43 00
39、0 295 23 37 17421712 300 20 500 83 000 570 43 000 295 22 35 174217F (FH) (Quenched and tempered, or . 4 100 90 000 620 55 000 380 20 39 187235normalized, quenched and tempered) 4 100 7 175 85 000 585 50 000 345 20 39 1742177 175 10 254 85 000 585 50 000 345 19 37 17421710 250 20 500 82 000 565 48 00
40、0 330 19 36 174217Alloy SteelG (GH) (Annealed, or normalized, or . 12 300 80 000 550 50 000 345 24 40 163207normalized and tempered) 12 300 20 500 80 000 550 50 000 345 22 38 163207H (HH) (Normalized and tempered) . 7 175 90 000 620 60 000 415 22 44 1872357 175 10 250 90 000 620 58 000 400 21 42 187
41、23510 250 20 500 90 000 620 58 000 400 18 40 187235J (JH) (Normalized and tempered, or . 7 175 95 000 655 70 000 485 20 50 197255normalized, quenched, and tempered) 7 175 10 250 90 000 620 65 000 450 20 50 18723510 250 20 500 90 000 620 65 000 450 18 48 207255K (KH) (Normalized, quenched, and temper
42、ed) . 7 178 105 000 725 80 000 550 20 50 2122697 175 10 250 100 000 690 75 000 515 19 50 20726910 250 20 500 100 000 690 75 000 515 18 48 207269L (LH) (Normalized, quenched, and tempered) . 4 100 125 000 860 105 000 725 16 50 2553214 100 7 175 115 000 795 95 000 655 16 45 2353027 175 10 250 110 000
43、760 85 000 585 16 45 22329310 250 20 500 110 000 760 85 000 585 14 40 223293M (MH) (Normalized, quenched, . 4 100 145 000 1000 120 000 825 15 45 293352and tempered) 4 100 7 175 140 000 965 115 000 790 14 40 2853417 178 10 254 135 000 930 110 000 758 13 40 26933110 250 20 500 135 000 930 110 000 758
44、12 38 269341N (NH) (Normalized, quenched, and tempered) . 4 100 170 000 1175 140 000 965 13 40 3314014 100 7 175 165 000 1140 135 000 930 12 35 3314017 175 10 250 160 000 1100 130 000 900 11 35 32138810 250 20 500 160 000 1100 130 000 900 11 35 321402AForgings with controlling cross section thicknes
45、s (TC) in excess of 20 in. 508 mm for all classes other than class D may be certified to Specification A668/A668M providedthey meet the requirements for controlling cross sections of 20 in. 508 mm listed in Table 2. Alternatively, the manufacturer and purchaser may agree upon the requiredmechanical
46、property values as described in Supplement S9.1.BRequirements presented in Table 2 are to be met at the test locations given in 7.1.4. Tests from other locations may not exhibit the property values shown in Table 2.A668/A668M 1313FIG. 1 Examples of Locations of Test Specimens for Various Types of Fo
47、rgings (see Note 1).A668/A668M 1314FIG. 2 Examples of Locations of Test Specimens for Various Types of Forgings (see Note 1).A668/A668M 1315thickness (TC), and have been heat treated in the same furnacecharge as the forging(s) it represents; or (2) obtain the testspecimen from the trepanned material
48、 of transverse or radialholes, provided the required depth is met.7.1.4.5 With prior purchaser approval, test specimens maybe taken at a depth (t) corresponding to the distance from thearea of significant stress to the nearest heat treated surface andat least twice this distance (2t) from any second
49、 surface.However, the test depth shall not be nearer to one heat-treatedsurface than34 in. 19 mm and to the second heat treatedsurface than 112 in. 38 mm. Sketches showing the exact testlocations shall be approved by the purchaser when this methodis used.7.1.5 Tests for acceptance shall be made after final heattreatment of the forgings. Thermal cycling after mechanicalt
