1、Designation: A574 12Standard 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 in paren
2、theses 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 quenchedand tempered
3、alloy steel hexagon socket-head cap screws,0.060 through 4 in. in diameter where high strength is required.1.2 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.NOTE 1Acomplete metric companion to SpecificationA574 has bee
4、ndevelopedA574M; therefore no metric equivalents are presented in thisspecification.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
5、with its use. It is theresponsibility of the user 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:2A751 Test Methods, Practices, and Terminology for Chemi-cal Anal
6、ysis of Steel ProductsE112 Test Methods for Determining Average Grain SizeF606 Test Methods for Determining the Mechanical Prop-erties of Externally and Internally Threaded Fasteners,Washers, Direct Tension Indicators, and RivetsF788/F788M Specification for Surface Discontinuities ofBolts, Screws, a
7、nd Studs, Inch and Metric SeriesF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance InspectionF1789 Terminology for F16 Mechanical FastenersF1940 Test Method for Process Control Verification toPrevent Hydrogen Embrittlement in Plated or CoatedFastenersF2282 Spec
8、ification for Quality Assurance Requirementsfor Carbon and Alloy Steel Wire, Rods, and Bars forMechanical FastenersF2328 Test Method for Determining Decarburization andCarburization in Hardened and Tempered Threaded SteelBolts, Screws and Studs2.2 ASME Standards:3B18.3 Socket Cap, Shoulder, and Set
9、ScrewsB18.12 Glossary of Terms for Mechanical FastenersB18.24 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 F1789, ASME
10、 B18.12, or the appli-cable referenced standards, unless 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
11、.1 ASTM designation and year of issue.4.1.2 Name of the 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.4.2 Orders for socket head cap screws shall include thefollowing optional requirements if speci
12、fied by the purchaser:4.2.1 Inspection 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 pa
13、ckaging (see 18.1.2).4.2.6 Supplementary requirements (see S1).1This 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 April 1, 2012. Published May 2012. O
14、riginallyapproved in 1967. Last previous edition approved in 2011 as A574 11. DOI:10.1520/A0574-12.2For 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 Doc
15、ument Summary page onthe ASTM website.3Available from American Society of Mechanical Engineers (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 Bar
16、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.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 c
17、ontroversy over grainsize, referee tests on finished screws conducted in accordancewith Test Methods E112 shall prevail.5.2 Screws in sizes through 0.750 in. diameter, and withlengths through ten times the nominal product size or 6.0inches, whichever is shorter, shall be cold headed, except thatwhen
18、 specified by the purchaser the screws shall be hot headed.Larger sizes and longer lengths shall be cold or hot headed atthe option of the manufacturer, unless otherwise specified bythe purchaser. Screws larger than 1.500 in. nominal diametershall be permitted to be machined. Sockets shall be forged
19、 ormachined at the option of the manufacturer.5.3 Screws in sizes through 0.625 in. diameter, and forproduct lengths through 4 in. 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
20、heat treated by quenching in oil fromabove the transformation temperature and then tempered byreheating to at least 700F to achieve the mechanical propertiesspecified in Section 7 and Table 1.5.4.1 When specified by the purchaser, the minimum tem-pering temperature shall be verified by subjecting sc
21、rews to680F for 30 minutes at temperature. The mean cross sectionhardness of three readings on the screw before and afterretempering shall not differ by more than 2 points hardnessRockwell C (HRC).5.5 Standard FinishesUnless otherwise specified, thescrews shall be furnished with one of the following
22、 “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.5.6 Protective Coatings:5.6.1 When a protective finish other th
23、an as specified in 5.5is required, it shall be specified on the purchase order with theapplicable finish specification.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-cis
24、ed. Additional precautions such as the requirements in TestMethod F1940 and Test Methods F606 shall be by agreementwith the purchaser.6. Chemical Composition6.1 The screws shall be alloy steel conforming to thechemical composition specified in Table 2 and the require-ments in Specification F2282. Se
25、e Supplementary RequirementS1 when additional alloy steel grades are required.6.2 One or more of the following alloying elements: chro-mium, nickel, molybdenum, or vanadium shall be present insufficient quantity to ensure that the specified strength proper-ties are met after oil quenching and temper
26、ing. As a guide forselecting material, an alloy steel should be capable of meetingthe specified mechanical requirements if the “as oil quenched”core hardness one diameter from the point is equal to orexceeds 25 HRC + (55 3 carbon content).6.3 When product analyses are made by the purchaser fromfinis
27、hed screws representing each lot, the chemical composi-tion, thus determined, shall conform to the requirementsprescribed 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 perform
28、ed in accordancewith Test Methods, Practices, and Terminology A751.7. Mechanical Properties7.1 Socket 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, andeither Table 4 or Table 5.7.2 The
29、 screws that are tested for wedge tensile strengthshall utilize a wedge of the angle specified in Table 6 under thehead. 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. Sc
30、rewsthreaded to the head shall pass the requirements for this test ifthe fracture that caused failure originated in the 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
31、be no evidence of carburization or totaldecarburization on the surfaces of the heat-treated screws whenmeasured in accordance with Test Method F2328 (Class 3Product).TABLE 1 Mechanical RequirementsProperty#0.500 in.Nom. Dia.0.500 in.Nom. Dia.Full-size screws:Tensile or wedge tensile strength, min, k
32、si 180 170Proof load (stress), ksi 140 135Product hardness:Rockwell (HRC) 3945 3745Machined test specimen:Yield 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 %TABLE 2 Chemical RequirementsElementCompositio
33、n, %HeatAnalysisProductAnalysisCarbon, min 0.33 0.31Phosphorus, max 0.035 0.040Sulfur, max 0.040 0.045Alloying elements See 6.2A574 1228.1.2 The depth of partial decarburization shall be limited tothe values in Test Method F2328 (Class 3 Product) whenmeasured as described therein.9. Dimensions9.1 Un
34、less otherwise specified, the product shall conform tothe requirements of ASME B18.3.10. Workmanship, Finish and Appearance10.1 Surface DiscontinuitiesThe surface discontinuitiesfor these products shall conform to Specification F788/F788Mand the additional limitations specified herein.10.2 Forging C
35、racks:10.2.1 Forging cracks that connect the socket to the periph-ery of the head as shown in Fig. 1 are not permissible.TABLE 3 Mechanical Testing RequirementsItem DescriptionTensile Load,min, lbProductLengthHardness,maxHardness,minDecarb/CarburizationTest Conducted UsingFull Size ProductTest Condu
36、cted UsingMachined Test SpecimenProofLoadWedgeTensileStrengthAxialTensileStrengthYieldStrengthat 0.2%OffsetTensileStrengthElongation% Red.of Area1 All short lengths Less than 3DAB B B. . . . . . .2 #0.5 in. D #270,000 3D to 1.5 in.B.BZCXC. . . . .3 #0.5 in. D #270,000 Over 3DB.BZCXC. YCYCYCYC4 0.5 i
37、n. D 0.5 in. D 270,000 Over 3DB.BZC. XCYCYCYCYCAD denotes nominal diameter of product.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 load test denotedZ shall be conducted
38、 when purchaser requests the test in inquiry and order.TABLE 4 Tensile Requirements for Coarse Thread ScrewsScrewDia (D),in.Threads/in.TensileLoad,min, lbfAStressArea,in.2 BProof Load(LengthMeasurementMethod),min, lbfC0.073 64 473 0.00263 3680.086 56 666 0.00370 5180.099 48 877 0.00487 6820.112 40 1
39、 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 0.226 30 5000.7
40、50 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 0002.500 4 680 000
41、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 000AValues based on 180 ksi for 0.500 and smaller and 170 ksi for sizes larger than0.500 in. and stress ar
42、ea in accordance with Footnote B.BStress areas based on Handbook H-28 (U.S. Department of Commerce) asfollows:As5 0.7854 D 0.9743/n!#2where:As= stress area,D = nominal screw size, andn = threads/in.CValues based on 140 ksi for 0.500 and smaller and 135 ksi for sizes larger than0.500 in. and stress a
43、rea in accordance with Footnote B.TABLE 5 Tensile Requirements for Fine Thread ScrewsScrewDia (D),in.Threads/in.TensileLoad,min, lbfAStressArea,in.2 BProof Load(LengthMeasurementMethod)min, lbfC0.060 80 324 0.00180 2520.073 72 500 0.00278 3890.086 64 709 0.00394 5520.099 56 941 0.00523 7320.112 48 1
44、 190 0.00661 9250.125 44 1 490 0.00830 1 1600.138 40 1 830 0.01015 1 4200.164 36 2 650 0.01474 2 0600.190 32 3 600 0.0200 2 8000.250 28 6 500 0.0364 5 1000.3125 24 10 400 0.0580 8 1200.375 24 15 800 0.0878 12 3000.4375 20 21 400 0.1187 16 6000.500 20 28 800 0.1599 22 4000.625 18 43 500 0.256 34 6000
45、.750 16 63 400 0.373 50 4000.875 14 86 500 0.509 68 7001.000 12 113 000 0.663 89 5001.125 12 146 000 0.856 116 0001.250 12 182 000 1.073 145 0001.375 12 224 000 1.315 178 0001.500 12 269 000 1.581 213 000AValues based on 180 ksi for 0.500 and smaller and 170 ksi for sizes larger than0.500 in. and st
46、ress area in accordance with Footnote B.BStress areas based on H-28 as follows:As5 0.7854 D 0.9743/n!#2where:As= stress area,D = nominal screw size, andn = threads/in.CValues based on 140 ksi for 0.500 and smaller and 135 ksi for sizes larger than0.500 in. and stress area in accordance with Footnote
47、 B.A574 12310.2.2 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 thosethat are located in the bearing area, fillet,
48、and top surfaces donot have a depth exceeding 0.03D or 0.005 in., whichever isgreater. For peripheral discontinuities, the maximum depthshall be 0.06D or 0.064 in., whichever is greater (see Fig. 1).10.2.4 Forging cracks located in the socket wall within 0.1times the actual key engagement (T) from t
49、he 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 0.005 in., whichever is greater(see Fig. 2).10.3 Seams in the shank shall not exceed a depth of 0.03Dor 0.005 in., 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 SpecificationF788/F788M, S1.2. Laps are permissible at the thread crest(Fig. 3C) to a depth of 25 % of th
