1、Designation: A 574M 08Standard Specification forAlloy Steel Socket-Head Cap Screws Metric1This standard is issued under the fixed designation A 574M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope*1.1 This specification covers the requirements for quenchedan
3、d tempered alloy steel hexagon socket-head cap screws, 1.6mm through 48 mm in diameter having a minimum ultimatetensile strength of 1220 MPa.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.NOTE 1This specification is the met
4、ric companion of SpecificationA 574.1.3 The following hazard caveat pertains only to the testmethod portions, sections 5.1, 5.6, 8, and 12, of this specifi-cation. This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the use
5、r of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A 751 Test Methods, Practices, and Terminology forChemical Analysis of Steel ProductsE112 Test Methods for Deter
6、mining Average Grain SizeF 606M Test Methods for Determining the MechanicalProperties of Externally and Internally Threaded Fasteners,Washers, and Rivets (Metric)F 788/F 788M Specification for Surface Discontinuities ofBolts, Screws, and Studs, Inch and Metric SeriesF 1470 Practice for Fastener Samp
7、ling for Specified Me-chanical Properties and Performance InspectionF 1789 Terminology for F16 Mechanical FastenersF 1940 Test Method for Process Control Verification toPrevent Hydrogen Embrittlement in Plated or CoatedFastenersF 2282 Specification for Quality Assurance Requirementsfor Carbon and Al
8、loy Steel Wire, Rods, and Bars forMechanical FastenersF 2328M Test Method for Determining Decarburization andCarburization in Hardened and Tempered Threaded SteelBolts, Screws and Studs (Metric)2.2 ASME Standards:3B18.3.1M Metric Socket Head Cap ScrewsB18.12 Glossary of Terms for Mechanical Fastener
9、sB18.24 Part Identifying Number (PIN) Code System Stan-dard for B18 Fastener Products3. Terminology3.1 Definitions of Terms Specific to This StandardThedefinition of terms used in this specification shall be asspecified in Terminology F 1789, ASME B18.12, or the appli-cable referenced standards, unl
10、ess otherwise defined herein. Inthe event that there are differences for a given term ASTMdefinitions shall be used.4. Ordering Information4.1 Orders for socket head cap screws under this specifica-tion shall include the following information:4.1.1 ASTM designation and year of issue.4.1.2 Name of th
11、e screw (SHCS).4.1.3 Quantity (number of pieces by size).4.1.4 Dimensions, including nominal thread designation,thread, pitch, and nominal screw length (millimeters).4.2 Orders for socket head cap screws shall include thefollowing optional requirements if specified by the purchaser:4.2.1 Inspection
12、at point of manufacture.4.2.2 Coating, if a protective finish other than those, whichare described in 5.5, is required, it must be specified (see 5.6).4.2.3 Certified test reports, as required (see Section 15).4.2.4 Additional testing (see 12.1).4.2.5 Special packaging (see 18.1.2).1This specificati
13、on is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts,Nuts, Rivets and Washers.Current edition approved Dec. 1, 2008. Published January 2009. Originallyapproved in 1980. Last previous edition approved in 2004 as A 574M 0
14、41.2For 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.3Available from American Society of Mechanical Engineers (
15、ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.1*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.4.2.6 Supplementary
16、 requirements (see S1).4.2.7 Special requirements.4.2.8 For establishment of a part identifying system seeASME B18.24.5. Materials and Manufacture5.1 The screws shall be fabricated from alloy steel made toa fine grain practice. In the event of controversy over grainsize, referee tests on finished sc
17、rews conducted in accordancewith Test Methods E112shall prevail.5.2 Screws in sizes through M20, and with lengths throughten times the nominal product size or 150 mm, whichever isshorter, shall be cold headed, except that when specified by thepurchaser the screws shall be hot headed. Larger sizes an
18、dlonger lengths shall be cold or hot headed at the option of themanufacturer, unless otherwise specified by the purchaser.Screws M42 and larger shall be permitted to be machined.Sockets shall be forged or machined at the option of themanufacturer.5.3 Screws in sizes through M24, and product lengthst
19、hrough 150 mm inclusive, shall be roll threaded, unlessotherwise specified by the purchaser. Larger products shall berolled, cut, or ground at the option of the manufacturer.5.4 Screws shall be heat treated by quenching in oil fromabove the transformation temperature and then tempered byreheating to
20、 at least 380C to achieve the mechanical proper-ties specified in Section 7 and Table 1.5.4.1 When specified by the purchaser, the minimum tem-pering temperature shall be verified by subjecting screws to370C for 30 minutes at temperature. The mean cross sectionhardness of three readings on the screw
21、 before and afterretempering shall not differ by more than 20 points Vickers(DPH).5.5 Standard FinishesUnless otherwise specified, thescrews shall be furnished with one of the following “standardsurfaces as manufactured” at the option of the manufacturer:(1) bright uncoated, (2) thermal black oxide,
22、 or (3) chemicalblack oxide. Hydrogen embrittlement tests shall not be re-quired for screws furnished in these conditions.5.6 Protective Coatings:5.6.1 When a protective finish other than as specified in 5.5is required, it shall be specified on the purchase order with theapplicable finish specificat
23、ion.5.6.2 When protective or decorative coatings are applied tothe screws, precautions specified by the coating requirementsto minimize internal hydrogen embrittlement shall be exer-cised. Additional precautions such as the requirements in TestMethod F 1940 and Test Methods F 606M shall be by agree-
24、ment with the purchaser.6. Chemical Composition6.1 The screws shall be alloy steel conforming to thechemical composition specified in Table 2 and the require-ments of Specification F 2282. See Supplementary Require-ment S1 when additional alloy steel grades are required.6.2 One or more of the follow
25、ing alloying elements: chro-mium, nickel, molybdenum, or vanadium shall be present inthe steel in sufficient quantity to ensure the specified strengthproperties are met after oil quenching and tempering. As aguide for selecting material, an alloy steel should be capable ofmeeting the specified mecha
26、nical requirements if the “as oilquenched” core hardness one diameter from the point is equalto or exceeds 25 HRC + (55 3 carbon content).6.3 When product analyses are made by the purchaser fromfinished screws representing each lot, the chemical composi-tion, thus determined, shall conform to the re
27、quirementsprescribed for product analysis in Table 2.6.4 Steel to which bismuth, selenium, tellurium, or lead hasbeen intentionally added shall not be permitted.6.5 Chemical analyses shall be performed in accordancewith Test Methods, Practices, and Terminology A 751.7. Mechanical Properties7.1 Socke
28、t head cap screws shall be tested in accordancewith the mechanical testing requirements specified in Table 3,and shall meet the mechanical requirements in Table 1 andTable 4.7.2 The screws that are tested for wedge tensile strengthshall utilize a wedge of the angle specified in Table 5 under thehead
29、. To meet the requirements of the wedge test, there must bea tensile failure in the body or thread section. For the purposeof this test, failure means separation into two pieces. Screwsthreaded to the head shall pass the requirements for this test ifthe fracture that caused failure originated in the
30、 thread area,even though it may have propagated into the fillet area or thehead before separation.8. Metallurgical Requirement8.1 Carburization or Decarburization:8.1.1 There shall be no evidence of carburization or totaldecarburization on the surfaces of the heat-treated screws whenmeasured in acco
31、rdance with Test Method F 2328M (Class 4Product).8.1.2 The depth of partial decarburization shall be limited tothe values in Test Method F 2328M (Class 4 Product) whenmeasured as described therein.TABLE 1 Mechanical RequirementsProperty Class 12.9AFull-size screws:Tensile or wedge strength, min, MPa
32、 1220Proof load (stress), min, MPa 970Machined test specimen:Yield strength at 0.2 % offset, min, MPa 1100Tensile strength, min, MPa 1220Elongation in 5D,min,% 10AReduction of area, min, % 35Product hardness:Rockwell 38 to 44 HRCVickers 372 to 434 DPHAElongation is 2 percentage points higher than pr
33、operty class 12.9.TABLE 2 Chemical RequirementsElementComposition, %Heat Analysis Product AnalysisCarbon 0.33 to 0.48 0.31 to 0.50Phosphorus, max 0.035 0.040Sulfur, max 0.040 0.045Alloying elements See 6.2A574M0829. Dimensions9.1 Unless otherwise specified, the product shall conform tothe requiremen
34、ts of ASME B18.3.1M.10. Workmanship, Finish and Appearance10.1 Surface DiscontinuitiesThe surface discontinuitiesfor these products shall conform to Specification F 788/F 788M and the additional limitations specified herein.10.2 Forging Cracks:10.2.1 Forging cracks that connect the socket to the per
35、iph-ery of the head as shown in Fig. 1 are not permissible.10.2.2 Forging cracks originating on the periphery of thehead and with a traverse indicating a potential to intersect onthe top of the socket head as shown in Fig. 1 are notpermissible.10.2.3 Other forging cracks are permissible provided tho
36、sethat are located in the bearing area, fillet, and top surfaces donot have a depth exceeding 0.03D or 0.13 mm, whichever isgreater. For peripheral discontinuities, the maximum depthshall be 0.06D or 1.6 mm, whichever is greater (see Fig. 1).10.2.4 Forging cracks located in the socket wall within 0.
37、1times the actual key engagement (T) from the bottom of thesocket are not permissible. Discontinuities located elsewhere inthe socket shall not have a length exceeding 0.25T,oramaximum depth of 0.03D or 0.13 mm, whichever is greater(see Fig. 2).10.3 Seams in the shank shall not exceed a depth of 0.0
38、3Dor 0.13 mm, whichever is greater.10.4 Thread DiscontinuitiesThreads shall have no laps atthe root or on the flanks located below the pitch line, as shownin Fig. 3, when inspected in accordance with SpecificationF 788/F 788M, S1.2. Laps are permitted at the thread crest(Fig. 3C) that do not exceed
39、25 % of the basic thread height,and on the thread flanks above the pitch diameter. Longitudinalseams rolled beneath the root of the thread and across the crestsof the threads are acceptable within the limits of 10.3.11. Sampling and Number of Tests11.1 Guide F 1470 shall be used to determine the nec
40、essarysampling plan and the number of tests that must be performedto demonstrate that all of the requirements of this standard aremet for each lot.12. Test Methods12.1 Testing, to demonstrate that the requirements in 5.4.1,Section 7, or any additional mechanical tests that are requiredby the purchas
41、er have been met, shall be in accordance withTest Methods F 606M at room temperature.12.2 The inspection and evaluation of surface discontinui-ties shall be in accordance with the requirements in Specifica-tion F 788/F 788M.12.3 Decarburization and carburization tests shall be con-ducted in accordan
42、ce with Test Method F 2328M, Class 4.13. Inspection13.1 If the inspection described in 13.2 is required by thepurchaser, it shall be specified in the inquiry and contract ororder.13.2 The purchasers representative, upon reasonable no-tice, shall have free entry to all parts of the manufacturersworks
43、, or suppliers place of business, that concern theTABLE 3 Mechanical Testing RequirementsItem DescriptionTensile Load,min, kNProductLengthHardness,maxHardness,minDecarb/CarburizationTest Conducted UsingFull-Size ProductTest Conducted UsingMachined Test SpecimenProofLoadWedgeTensileStrengthAxialTensi
44、leStrengthYieldStrengthat 0.2 %OffsetTensileStrengthElongationReductionof Area1 All short lengths . . . #3DABB B. . . . . . .2 Smaller SHCS #1200 3D to 300 mmB.BZCXC. . . . .3 Smaller SHCS #1200 Over 300 mmB.B. XC. YCYCYCYC4 Larger SHCS $1200 3DB.BZC. XCYCYCYCYCAD denotes nominal diameter of product
45、.BDenotes mandatory test.CEither all tests denoted by X or all tests denoted by Y shall be performed. In case of arbitration full-size tests, denoted X, shall be decisive. Proof test denoted Z shallbe conducted when purchaser requests the test in inquiry and order.TABLE 4 Minimum Ultimate Tensile Lo
46、adsNOTEAll values are rounded to 3 significant digits.Thread SizeStress Area,mm2Tensile Load,min, kNProof Load,kNM1.6 3 0.35 1.27 1.55 1.23M2 3 0.4 2.07 2.53 2.01M2.5 3 0.45 3.39 4.14 3.2M3 3 0.5 5.03 6.14 4.88M4 3 0.7 8.78 10.7 8.52M5 3 0.8 14.2 17.3 13.8M6 3 1 20.1 24.5 19.5M8 3 1.25 36.6 44.6 35.
47、5M10 3 1.5 58.0 70.8 56.3M12 3 1.75 84.3 103 81.8M14 3 2 115 140 112M16 3 2 157 192 152M20 3 2.5 245 299 238M24 3 3 353 431 342M30 3 3.5 561 684 544M36 3 4 817 997 792M42 3 4.5 1120 1370 1090M48 3 5 1470 1790 1430TABLE 5 Wedge Test AngleProduct Diameter, mm degreeSocket-head cap screws threaded 2D a
48、nd through 20 6closer to underside of head over 20 to 36 4All other socket-head cap screws through 12 10over 12 to 16 8over 16 to 36 6A574M083manufacture or supply of the material ordered. The manufac-turer or supplier shall afford the purchasers representative allreasonable facilities to satisfy hi
49、m that the material is beingfurnished in accordance with this specification. All tests andinspections required by the specification that are requested bythe purchasers representative shall be made before shipment,FIG. 1 Head and Body Discontinuity Location and LimitsFIG. 2 Socket Discontinuity Location and LimitsA574M084and shall be conducted so as not to interfere unnecessarily withthe operation of the manufacturers works or suppliers placeof business.14. Rejection and Rehearing14.1 The disposition of nonconforming lots shall be inaccordance with the provisions
