1、Designation: A574 12A574 13Standard Specification forAlloy Steel Socket-Head Cap Screws1This standard is issued under the fixed designation A574; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number i
2、n 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 quenched and t
3、empered alloy steel hexagon socket-head cap screws, 0.060through 4 in. in diameter where high strength is required.1.2 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in thisstandard.NOTE 1A complete metric companion to Specification A
4、574 has been developedA574M; therefore no metric equivalents are presented in thisspecification.1.3 The following hazard caveat pertains only to the test method portions, sections 5.1, 5.6, 8, and 12, of this specification. Thisstandard does not purport to address all of the safety concerns, if any,
5、 associated with its use. It is the responsibility of the userof this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2A751 Test Methods, Practices, and Terminology for Chemi
6、cal Analysis of Steel ProductsE112 Test Methods for Determining Average Grain SizeF606 Test Methods for Determining the Mechanical Properties of Externally and Internally Threaded Fasteners, Washers, DirectTension Indicators, and RivetsF788/F788M Specification for Surface Discontinuities of Bolts, S
7、crews, and Studs, Inch and Metric SeriesF1470 Practice for Fastener Sampling for Specified Mechanical Properties and Performance InspectionF1789 Terminology for F16 Mechanical FastenersF1940 Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated FastenersF
8、2282 Specification for Quality Assurance Requirements for Carbon and Alloy Steel Wire, Rods, and Bars for MechanicalFastenersF2328 Test Method for Determining Decarburization and Carburization in Hardened and Tempered Threaded Steel Bolts,Screws and Studs2.2 ASME Standards:3B18.3 Socket Cap, Shoulde
9、r, and Set ScrewsB18.12 Glossary of Terms for Mechanical FastenersB18.24 Part Identifying Number (PIN) Code System Standard for B18 Fastener Products3. Terminology3.1 Definitions of Terms Specific to This StandardThe definition of terms used in this specification shall be as specified inTerminology
10、F1789,ASME B18.12, or the applicable referenced standards, unless otherwise defined herein. In the event that thereare differences for a given term, ASTM definitions shall be used.1 This specification is under the jurisdiction of ASTM Committee F16 on Fasteners and is the direct responsibility of Su
11、bcommittee F16.02 on Steel Bolts, Nuts, Rivetsand Washers.Current edition approved April 1, 2012April 1, 2013. Published May 2012June 2013. Originally approved in 1967. Last previous edition approved in 20112012 asA574 11.A574 12. DOI: 10.1520/A0574-12.10.1520/A0574-13.2 For referencedASTM standards
12、, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from American Society of Mechanical Engineers (ASME), ASME International Headqu
13、arters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict
14、 all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standardCopyright ASTM International
15、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Ordering Information4.1 Orders for socket head cap screws under this specification shall include the following information:4.1.1 ASTM designation and year of issue.4.1.2 Name of the screw (SHCS).4.1.3 Quantity (
16、number of pieces by size).4.1.4 Dimensions, including nominal thread designation, thread pitch, and nominal screw length.4.2 Orders for socket head cap screws shall include the following optional requirements if specified by the purchaser:4.2.1 Inspection at point of manufacture.4.2.2 Coating, if a
17、protective finish other than those, which are 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).4.2.6 Supplementary requirements (see S1).4.2.7 Special requi
18、rements.4.2.8 For establishment of a part identifying system, see ASME B18.24.5. Materials and Manufacture5.1 The screws shall be fabricated from alloy steel made to a fine grain practice. In the event of controversy over grain size,referee tests on finished screws conducted in accordance with Test
19、Methods E112 shall prevail.5.2 Screws in sizes through 0.750 in. diameter, and with lengths through ten times the nominal product size or 6.0 inches,whichever is shorter, shall be cold headed, except that when specified by the purchaser the screws shall be hot headed. Larger sizesand longer lengths
20、shall be cold or hot headed at the option of the manufacturer, unless otherwise specified by the purchaser.Screws larger than 1.500 in. nominal diameter shall be permitted to be machined. Sockets shall be forged or machined at the optionof the manufacturer.5.3 Screws in sizes through 0.625 in. diame
21、ter, and for product lengths through 4 in. shall be roll threaded, unless otherwisespecified by the purchaser. Larger products shall be rolled, cut, or ground at the option of the manufacturer.5.4 Screws shall be heat treated by quenching in oil from above the transformation temperature and then tem
22、pered by reheatingto at least 700F to achieve the mechanical properties specified in Section 7 and Table 1.5.4.1 When specified by the purchaser, the minimum tempering temperature shall be verified by subjecting screws to 680F for30 minutes at temperature. The mean cross section hardness of three re
23、adings on the screw before and after retempering shall notdiffer by more than 2 points hardness Rockwell C (HRC).5.5 Standard FinishesUnless otherwise specified, the screws shall be furnished with one of the following “standard surfacesas manufactured” at the option of the manufacturer: (1) bright u
24、ncoated, (2) thermal black oxide, or (3) chemical black oxide.Hydrogen embrittlement tests shall not be required for screws furnished in these conditions.5.6 Protective Coatings:5.6.1 When a protective finish other than as specified in 5.5 is required, it shall be specified on the purchase order wit
25、h theapplicable finish specification.5.6.2 When protective or decorative coatings are applied to the screws, precautions specified by the coating requirements tominimize internal hydrogen embrittlement shall be exercised. Additional precautions such as the requirements in Test MethodF1940 and Test M
26、ethods F606 shall be by agreement with the purchaser.TABLE 1 Mechanical RequirementsProperty #0.500 in.Nom. Dia. 0.500 in.Nom. Dia.Full-size screws:Tensile or wedge tensile strength, min, ksi 180 170Proof load (stress), ksi 140 135Product hardness:Rockwell (HRC) 3945 3745Machined test specimen:Yield
27、 strength at 0.2% offset, min., ksi 153 153Tensile strength, min., ksi 180 170Elongation in 5D, min. 10 % 10 %Reduction of area, min. 35 % 35 %A574 1326. Chemical Composition6.1 The screws shall be alloy steel conforming to the chemical composition specified in Table 2 and the requirements inSpecifi
28、cation F2282. See Supplementary Requirement S1 when additional alloy steel grades are required.6.2 One or more of the following alloying elements: chromium, nickel, molybdenum, or vanadium shall be present in sufficientquantity to ensure that the specified strength properties are met after oil quenc
29、hing and tempering.As a guide for selecting material,an alloy steel should be capable of meeting the specified mechanical requirements if the “as oil quenched” core hardness onediameter from the point is equal to or exceeds 25 HRC + (55 carbon content).6.3 When product analyses are made by the purch
30、aser from finished screws representing each lot, the chemical composition,thus determined, shall conform to the requirements prescribed for product analysis in Table 2.6.4 Steel to which bismuth, selenium, tellurium, or lead has been intentionally added shall not be permitted.6.5 Chemical analyses s
31、hall be performed in accordance with Test Methods, Practices, and Terminology A751.7. Mechanical Properties7.1 Socket head cap screws shall be tested in accordance with the mechanical testing requirements specified in Table 3, and shallmeet the mechanical requirements in Table 1, and either Table 4
32、or Table 5.7.2 The screws that are tested for wedge tensile strength shall utilize a wedge of the angle specified in Table 6 under the head.To meet the requirements of the wedge test, there must be a tensile failure in the body or thread section. For the purpose of thistest, failure means separation
33、 into two pieces. Screws threaded to the head shall pass the requirements for this test if the fracturethat caused failure originated in the thread area, even though it may have propagated into the fillet area or the head beforeseparation.8. Metallurgical Requirement8.1 Carburization or Decarburizat
34、ion :8.1.1 There shall be no evidence of carburization or total decarburization on the surfaces of the heat-treated screws whenmeasured in accordance with Test Method F2328 (Class 3 Product).8.1.2 The depth of partial decarburization shall be limited to the values in Test Method F2328 (Class 3 Produ
35、ct) when measuredas described therein.9. Dimensions9.1 Unless otherwise specified, the product shall conform to the requirements of ASME B18.3.10. Workmanship, Finish, and Appearance10.1 Surface DiscontinuitiesThe surface discontinuities for these products shall conform to Specification F788/F788M a
36、ndthe additional limitations specified herein.10.2 Forging Cracks:10.2.1 Forging cracks that connect the socket to the periphery of the head as shown in Fig. 1 are not permissible.10.2.2 Forging cracks originating on the periphery of the head and with a traverse indicating a potential to intersect o
37、n the topof the socket head as shown in Fig. 1 are not permissible.10.2.3 Other forging cracks are permissible provided those that are located in the bearing area, fillet, and top surfaces do nothave a depth exceeding 0.03D or 0.005 in., whichever is greater. For peripheral discontinuities, the maxi
38、mum depth shall be 0.06Dor 0.064 in., whichever is greater (see Fig. 1).10.2.4 Forging cracks located in the socket wall within 0.1 times the actual key engagement (T) from the bottom of the socketare not permissible. Discontinuities located elsewhere in the socket shall not have a length exceeding
39、0.25T, or a maximum depthof 0.03D or 0.005 in., whichever is greater (see Fig. 2).10.3 Seams in the shank shall not exceed a depth of 0.03D or 0.005 in., whichever is greater.TABLE 2 Chemical RequirementsElementComposition, %HeatAnalysisProductAnalysisCarbon, min 0.33 0.31Phosphorus, max 0.035 0.040
40、Sulfur, max 0.040 0.045Alloying elements See 6.2A574 133TABLE 3 Mechanical Testing RequirementsItem DescriptionTensileLoad,min, lbProductLengthHardness,maxHardness,minDecarb/CarburizationTest Conducted UsingFull Size ProductTest Conducted UsingMachined Test SpecimenProofLoadWedgeTensileStrengthAxial
41、TensileStrengthYieldStrengthat 0.2%OffsetTensileStrength Elongation% Red.of Area1 All shortlengths Less than3D AB B B . . . . . . .2 #0.5 in. D #270,000 3D to 1.5in.B . B ZC XC . . . . .3 #0.5 in. D #270,000 Over 3D B . B ZC XC . YC YC YC YC4 0.5 in. D 0.5 in. D #270,000 Over 3D B . B ZC XC . YC YC
42、YC YC5 0.5 in. D 270,000 Over 3D B . B ZC . XC YC YC YC YCA D denotes nominal diameter of product.B Denotes mandatory test.C Either 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 load test denoted Zshal
43、l be conducted when purchaser requests the test in inquiry and order.TABLE 4 Tensile Requirements for Coarse Thread ScrewsScrewDia (D),in.Threads/in.TensileLoad,min, lbf AStressArea,in.2 BProof Load(LengthMeasurementMethod),min, lbf C0.073 64 473 0.00263 3680.086 56 666 0.00370 5180.099 48 877 0.004
44、87 6820.112 40 1 090 0.00604 8460.125 40 1 430 0.00796 1 1100.138 32 1 640 0.00909 1 2700.164 32 2 520 0.0140 1 9600.190 24 3 150 0.0175 2 4500.250 20 5 730 0.0318 4 4500.3125 18 9 440 0.0524 7 3400.375 16 13 900 0.0775 10 8000.4375 14 19 100 0.1063 14 9000.500 13 25 500 0.1419 19 9000.625 11 38 400
45、 0.226 30 5000.750 10 56 800 0.334 45 1000.875 9 78 500 0.462 62 4001.000 8 103 000 0.606 81 8001.125 7 129 000 0.763 103 0001.250 7 165 000 0.969 131 0001.375 6 196 000 1.155 156 0001.500 6 239 000 1.405 190 0001.750 5 323 000 1.90 256 0002.000 412 425 000 2.50 338 0002.250 412 552 000 3.25 439 000
46、2.500 4 680 000 4.00 540 0002.750 4 838 000 4.93 666 0003.000 4 1 010 000 5.97 806 0003.250 4 1 210 000 7.10 958 0003.500 4 1 420 000 8.33 1 120 0003.750 4 1 640 000 9.66 1 300 0004.000 4 1 880 000 11.08 1 500 000A Values based on 180 ksi for 0.500 and smaller and 170 ksi for sizes larger than0.500
47、in. and stress area in accordance with Footnote B.B Stress areas based on Handbook H-28 (U.S. Department of Commerce) asfollows:As50.7854 fD2s0.9743/ndg2where:As = stress area,D = nominal screw size, andn = threads/in.C Values based on 140 ksi for 0.500 and smaller and 135 ksi for sizes larger than0
48、.500 in. and stress area in accordance with Footnote B.A574 13410.4 Thread DiscontinuitiesThreads shall have no laps at the root or on the flanks located below the pitch line, as shown inFig. 3, when inspected in accordance with Specification F788/F788M, S1.2. Laps are permissible at the thread cres
49、t (Fig. 3C) toa depth of 25 % of the basic thread height and on the thread flanks above the pitch diameter. Longitudinal seams rolled beneaththe root of the thread and across the crests of the threads are acceptable within the limits of 10.3.11. Sampling and Number of Tests11.1 Guide F1470 shall be used to determine the necessary sampling plan and the number of tests that must be performed todemonstrate that all of the requirements of this standard are met for each lot.12. Test Methods12.1 Testing, to demonstrate that the requirements in 5.4.1, Section 7, or
