1、Designation: A 574M 04e1METRICStandard 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
2、. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTESections 2.2 and 3.2.8 were editorially revised in Octo
3、ber 2006.1. Scope*1.1 This specification covers the requirements for quenchedand tempered alloy steel socket-head cap screws 1.6 mmthrough 48 mm in diameter having a minimum ultimate tensilestrength of 1220 MPa.NOTE 1This specification is the metric companion of SpecificationA 574.1.2 The following
4、hazard caveat pertains only to the testmethod portion, Section 10, of this specification: This standarddoes not purport to address all of the safety concerns, if any,associated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand
5、determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2A 751 Test Methods, Practices, and Terminology forChemical Analysis of Steel ProductsD 3951 Practice for Commercial PackagingE3 Guide for Preparation of Metallographic SpecimensE18 Test Metho
6、ds for Rockwell Hardness and RockwellSuperficial Hardness of Metallic MaterialsE112 Test Methods for Determining Average Grain SizeE 384 Test Method for Microindentation Hardness of Ma-terialsF 606M Test Methods for Determining the MechanicalProperties of Externally and Internally Threaded Fasteners
7、,Washers, and Rivets MetricF 788/F 788M Specification for Surface Discontinuities ofBolts, Screws, and Studs, Inch and Metric Series2.2 ASME Standards:3B18.3.1M Metric Socket Head Cap ScrewsB18.24 Part Identifying Number (PIN) Code System Stan-dard for B18 Fastener Products3. Ordering Information3.1
8、 Orders for socket head cap screws under this specifica-tion shall include the following information:3.1.1 Quantity (number of screws),3.1.2 Dimensions, including nominal thread designation,thread, pitch, and nominal screw length (millimetres),3.1.3 Name of the screw (SHCS),3.1.4 ASTM designation an
9、d year of issue.3.2 Orders for socket head cap screws may include thefollowing optional requirements:3.2.1 Inspection at point of manufacture.3.2.2 Coating, if required (see 4.6).3.2.3 Certified Test Reports (see 9.2).3.2.4 Additional Testing (see 9.3 and 11.1).3.2.5 Special Packaging (see 14.1.2).3
10、.2.6 Supplementary Requirement (see S1).3.2.7 Special Requirements.3.2.8 For establishment of a part identifying system, seeASME B18.244. Materials and Manufacture4.1 The screws shall be fabricated from steel made to finegrain practice. In the event of controversy over grain size,referee tests on fi
11、nished screws conducted in accordance withTest Methods E112shall prevail.4.2 Screws in sizes up to M20 inclusive, and with lengths upto ten times the nominal product size or 150 mm, whichever isshorter, shall be cold headed, except that they may be hotheaded by agreement of the purchaser. Larger siz
12、es and longer1This specification 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 Aug. 1, 2004. Published August 2004. Originallyapproved in 1980. Last previous edition
13、 approved in 2000 as A 574M00.2For 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 Societ
14、y of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990.1*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.lengths may
15、be cold or hot headed. Screws M42 and larger maybe machined. Sockets may be forged or machined at the optionof the manufacturer.4.3 Screws in sizes up to M24 inclusive, and product lengthsup to 150 mm inclusive, shall be roll threaded, except byspecial agreement of the purchaser. Larger products may
16、 berolled, cut, or ground at the option of the manufacturer.4.4 Socket-head cap screws shall be heat treated by quench-ing in oil from above the transformation temperature and thentempered by reheating to at least 380C to within the hardnessrange specified in Table 1.4.4.1 The minimum tempering temp
17、erature may be verifiedby submitting screws to 370C for 30 min at temperature. Themean cross section hardness of three readings on the screwbefore and after retempering shall not differ by more than 20DPH.4.5 Standard FinishesUnless otherwise specified, thescrews shall be furnished with one of the f
18、ollowing “standardsurfaces as manufactured,” at the option of the manufacturer;(1) bright uncoated, (2) thermal black oxide, or (3) chemicalblack oxide. Hydrogen embrittlement tests shall not be re-quired for screws furnished in these conditions.4.6 Protective Coatings:4.6.1 When a protective finish
19、 other than as specified in 4.5is required, it shall be specified on the purchase order with theapplicable finish specification.4.6.2 When protective or decorative coatings are applied tothe screws, precautions specified by the coating requirementsto minimize embrittlement shall be exercised.5. Chem
20、ical Composition5.1 The screws shall be alloy steel conforming to thechemical composition specified in Table 2. See SupplementaryRequirement S1 when specific chemistry grades are required.5.2 One or more of the following alloying elements: chro-mium, nickel, molybdenum, or vanadium shall be present
21、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 mechanical requirements if the “as oilquenched” core hardness one diameter from the poin
22、t is equalto or exceeds 25 HRC + (55 3 carbon content).5.3 Product analyses may be made by the purchaser fromfinished screws representing each lot. The chemical composi-tion thus determined shall conform to the requirements speci-fied for the product analysis in Table 2.5.4 Steel to which bismuth, s
23、elenium, tellurium, or lead hasbeen intentionally added shall not be permitted.5.5 Chemical analyses shall be performed in accordancewith Test Methods, Practices, and Terminology A 751.6. Mechanical Properties6.1 Socket head cap screws shall be tested in accordancewith the mechanical testing require
24、ments specified in Table 3,and shall meet the mechanical requirements in Table 1 andTable 4.6.2 Screws in sizes 1.6 through 36-mm diameter shall bewedge tensile tested in accordance with Table 3, using wedgeangles as specified in Table 5.6.3 The hardness limits shall be met anywhere on the crosssect
25、ion through the threads, one diameter from the screw pointas determined using Test Methods E18.7. Dimensions7.1 Unless otherwise specified, the product shall conform tothe requirements of ASME B18.3.1M.8. Workmanship, Finish, and Appearance8.1 There shall be no evidence of carburization or grossdeca
26、rburization on the surfaces of the heat-treated screws whenmeasured in accordance with 10.2.8.2 The depth of partial decarburization shall be limited tothe values in Table 6 when measured as shown in Fig. 1, andin accordance with 10.2.8.3 The surface discontinuities for these products shallconform t
27、o Specification F 788/F 788M and the additionallimitations specified herein.8.3.1 Forging defects that connect the socket to the periph-ery of the head are not permissible. Defects originating on theperiphery and with a traverse indicating a potential to intersectand are not permissible. Other forgi
28、ng defects are permissibleprovided those located in the bearing area, fillet, and topsurfaces shall not have a depth exceeding 0.03D or 0.13 m,whichever is greater. For peripheral discontinuities, the maxi-mum depth may be 0.06D, but not to exceed 1.6 mm (see Fig.2).8.3.2 Forging defects located in
29、the socket wall within 0.1times the actual key engagement (T) from the bottom of thesocket are not permissible. Discontinuities located elsewhere inthe socket shall not have a length exceeding 0.25 T,oramaximum depth of 0.03D not to exceed 0.13 mm (see Fig. 3).8.3.3 Seams in the shank shall not exce
30、ed a depth of 0.03Dor 0.2 mm, whichever is greater.TABLE 1 Mechanical RequirementsProperty class 12.9AFull-size screws:Tensile or wedge strength, min, MPa 1220Proof load (stress), min, MPa 970Machined test specimen:Yield strength at 0.2 % offset, min, MPa 1100Tensile strength, min, MPa 1220Elongatio
31、n in 5D,min,% 10AReduction of area, min, % 35Product hardness:Rockwell 38 to 44 HRCVickers 372 to 434 DPHAElongation is 2 percentage points higher than property class 12.9.TABLE 2 Chemical RequirementsElement Composition, %Heat Analysis Product AnalysisCarbon 0.33 to 0.48 0.31 to 0.50Phosphorus, max
32、 0.035 0.040Sulfur, max 0.040 0.045Alloying elements See 5.2A574M04e128.3.4 No transverse discontinuities shall be permitted in thehead-to-shank fillet area.8.3.5 Threads shall have no laps at the root or on the flanks,as shown in Fig. 4. Laps are permitted at the crest (Fig. 4C) thatdo not exceed 2
33、5 % of the basic thread depth, and on the flanksoutside the pitch cylinder. Longitudinal seams rolled beneaththe root of the thread and across the crests of cut threads areacceptable within the limits of 8.3.3.8.3.6 Quench cracks of any depth, any length, or in anylocation are not permitted.9. Numbe
34、r of Tests9.1 The requirements of this specification shall be met incontinuous mass production for stock, and the manufacturershall make sample inspections to ensure that the productconforms to the specified requirements. Additional tests ofindividual shipments of material are not ordinarily contem-
35、plated.Arecord of individual heats of steel in each test lot shallbe maintained. The container shall be coded to permit identi-fication of the lot.9.2 When specified in the order, the manufacturer shallfurnish a test report certified to be the last complete set ofmechanical tests for each stock size
36、 in each shipment.9.3 When additional tests are specified on the purchaseorder, a lot, for purposes of selecting test samples, shall consistof all screws offered for inspection at one time of one diameterand length. From each lot, the number of samples for eachrequirement shall be as follows:TABLE 3
37、 Mechanical Testing RequirementsItem Description TensileLoad,min,kNProductLengthHard-ness,maxHard-ness,minDecar-buriza-tionTest Conducted UsingFull-Size ProductTest Conducted using Machined TestSpecimenProofLoadWedgeTensileStrengthAxialTensileStrengthYieldStrengthat0.2 %OffsetTensileStrengthElonga-t
38、ionReduc-tionofArea1Alshortlengths. #3DABBB. . . . . . .2 SmallerSHCS#1200 3Dto300mmB.BZCXC. . . . .3 SmallerSHCS#1200 Over300mmB.B. XC. YCYCYCYC4 LargerSHCS$1200 3DB.BZC. XCYCYCYCYCAD denotes nominal diameter of product.BDenotes mandatory test.CEither all tests denoted by X or all tests denoted by
39、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 LoadsNOTE 1All values are rounded to 3 significant digits.Thread Size Stress Area,
40、 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 3.2M33 0.5 5.03 6.14 4.88M43 0.7 8.78 10.7 8.52M53 0.8 14.2 17.3 13.8M63 1 20.1 24.5 19.5M83 1.25 36.6 44.6 35.5M103 1.5 58.0 70.8 56.3M123 1.75 84.3 103 81.8M143 2 115 140 112M163 2 157 192 1
41、52M203 2.5 245 299 238M243 3 353 431 342M303 3.5 561 684 544M363 4 817 997 792M423 4.5 1120 1370 1090M483 5 1470 1790 1430TABLE 5 Wedge Test AngleProduct Diameter, mm degreeSocket-head cap screws threaded 2D andcloser to underside of headthrough 20over 20 to 3664All other socket-head cap screws thro
42、ugh 12over 12 to 16over 16 to 361086TABLE 6 Decarburization Limits for ThreadsAThread Pitch P, mm Basic Thread Height h =0.6135P mmN =3/4 h,min,mm0.7 0.429 0.3220.8 0.491 0.3681 0.613 0.4601.25 0.767 0.5751.5 0.920 0.6901.75 1.074 0.8062 1.227 0.9202.5 1.534 1.1513 1.840 1.3803.5 2.147 1.6104 2.454
43、1.8414.5 2.761 2.0715 3.068 2.301ASee Fig. 4.A574M04e13Number of Pieces in LotNumber ofSamples800 and less 1Over 800 to 8 000, incl 2Over 8 000 to 22 000, incl 3Over 22 000 59.4 Should any sample fail to meet the requirements of aspecified test, double the number of samples from the same lotshall be
44、 retested for the requirement(s) in which it failed.All ofthe additional samples shall conform to the specification or thelot shall be rejected.FIG. 1 Decarburization LimitsFIG. 2 Head and Body Discontinuity Location and LimitsA574M04e1410. Test Methods10.1 Conduct tests for proof load, wedge tensil
45、e, andultimate tensile strength in accordance with Test MethodsF 606M.10.2 Decarburization and carburization tests shall be con-ducted as follows:10.2.1 Section the thread area of the bolt longitudinallythrough the axis, mount, and polish it in accordance withPractice E3. Take measurements (1) at th
46、e minor diameter inthe center of the thread ridge, and (2) 0.75 h toward the threadcrest on the perpendicular bisector of the thread ridge. Take ameasurement (3) on the thread flank approximately at the pitchline at a depth of 0.08 mm. Use one of the two methods forcarburization/decarburization eval
47、uation either optical or mi-crohardness measurements. The microhardness measurementshall constitute a referee method in case of dispute.10.2.2 For optical measurement, etch the section in 2 to 4 %nital. Examine the surface of the etched samples under amicroscope at 1003 using a measuring eyepiece gr
48、aduated in0.03-mm increments. The width of any light etching bandnormally defines the decarburization depth. A dark etchingband indicates the possibility of carburization.10.2.3 Measure microhardness in accordance with TestMethod E 384 on unetched specimens using a DPH 136indenter or a Knoop indente
49、r using the following load appli-cation:FIG. 3 Socket Discontinuity Location and LimitsFIG. 4 Thread DiscontinuitiesA574M04e15Thread Pitch, P min. LoadOver 0.6 500 gf0.6 200 gfLess than 0.6 Use optical evaluationin 10.3.210.2.3.1 Take measurements at minor diameter (ReadingNo. 1) on the thread crest bisector to determine base metalhardness. Take measurements (Reading No. 2) on the bisector0.75 h from the minor measurement toward the thread crest.Also take measurements (Reading No. 3) on the thread flank atthe pitch line at a depth within 0.08 mm from the surface.Reading N
