1、Designation: F 879M 02a (Reapproved 2008)Standard Specification forStainless Steel Socket Button and Flat Countersunk HeadCap Screws (Metric)1This standard is issued under the fixed designation F 879M; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 case of revision, the year of last revision. A number 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. Scope1.1 This s
3、pecification covers the chemical and mechanicalrequirements for stainless steel metric hexagon socket button(SBHCS) and flat countersunk (SFHCS) head cap screws withnominal thread M 3 through M 20 intended for use in applica-tions requiring general corrosion resistance.1.2 The following three proper
4、ty classes are covered:1.2.1 Austenitic Class A 1-50 in an annealed condition at585 MPa maximum,1.2.2 Austenitic Class A155 in a cold worked condition at550 MPa minimum, and1.2.3 Austenitic Class A 1-70 in a cold-worked condition at700 MPa minimum.1.3 UnitsThe values stated in SI units are to be reg
5、ardedas standard. No other units of measurement are included in thisstandard.1.4 The following hazard caveat pertains only to Section 12,Test Methods: This standard does not purport to address all ofthe safety problems, if any, associated with its use. It is theresponsibility of the user of this sta
6、ndard 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 262 Practices for Detecting Susceptibility to Intergranu-lar Attack in Austenitic Stainless SteelsA 342/A 342M Test Methods
7、 for Permeability of FeeblyMagnetic MaterialsA 380 Practice for Cleaning, Descaling, and Passivation ofStainless Steel Parts, Equipment, and SystemsA 555/A 555M Specification for General Requirements forStainless Steel Wire and Wire RodsA 751 Test Methods, Practices, and Terminology forChemical Anal
8、ysis of Steel ProductsA 967 Specification for Chemical Passivation Treatmentsfor Stainless Steel PartsD 3951 Practice for Commercial PackagingE18 Test Methods for Rockwell Hardness of MetallicMaterialsE92 Test Method for Vickers Hardness of Metallic Mate-rialsE 384 Test Method for Microindentation H
9、ardness of Ma-terialsF 606M Test Methods for Determining the MechanicalProperties of Externally and Internally Threaded Fasteners,Washers, and Rivets (Metric)F 738M Specification for Stainless Steel Metric Bolts,Screws, and Studs (Metric)F 788/F 788M Specification for Surface Discontinuities ofBolts
10、, Screws, and Studs, Inch and Metric SeriesF 1470 Guide for Fastener Sampling for Specified Mechani-cal Properties and Performance Inspection2.2 ASME Standards:B 18.3.4M Hexagon Socket Button Head Cap Screws (Met-ric Series)3B 18.3.5M Hexagon Socket Flat Countersunk Head CapScrews (Metric Series)33.
11、 Classification3.1 The designation of the property class and conditions ofthis specification shall be consistent with the stainless steeldesignations in Specification F 738M.3.2 The austenitic stainless steel socket screw shall bedesignated F879M A1-50, F879M A155, or F 879M A1-70.4. Ordering Inform
12、ation4.1 Orders for material under this specification shall includethe following information:4.1.1 Quantity (number of pieces of each item).1This specification is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.04 on NonferrousFasteners.C
13、urrent edition approved May 1, 2008. Published August 2008. Originallyapproved in 1984. Last previous edition approved in 2002 as F 879 02a.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volum
14、e information, refer to the standards Document Summary page onthe ASTM website.3Available from Global Engineering Documents, 15 Inverness Way, EastEnglewood, CO 80112-5704, http:/.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.1.2
15、 Name of the screw, SBHCS or SFHCS.4.1.3 Dimensions, including nominal thread designation,thread pitch, and nominal screw length (millimetres). A stan-dard part number may be used for this definition.4.1.4 Property Class A 1-50, A155, or A 1-70.4.1.5 Certification, if required (see Section 15).4.1.6
16、 ASTM specification and year of issue.4.1.7 Any special or supplemental requirements (seeSupplementary Requirements S1 through S3).5. Materials and Manufacture5.1 Screws shall be formed by upsetting or extruding, orboth.5.2 Screws shall be roll threaded.5.3 Heat TreatmentAustenitic alloys ClassA 1-5
17、0 screws,following manufacture, shall be annealed by heating to 1040 630C to obtain maximum corrosion resistance and minimumpermeability. The screws shall be held for a sufficient time attemperature, then cooled at a rate sufficient to prevent precipi-tation of the carbide and provide the properties
18、 specified inTable 1.5.4 When Property Class A1-55 or A1-70 is specified, theaustenitic alloys shall be annealed as specified in 5.3, generallyby the raw material manufacturer, then cold worked to developspecific properties.6. Chemical Composition6.1 It is the intent of this specification that screw
19、s shall beordered by property class. The chemical composition of thescrews shall conform to the requirements of Table 2.6.2 Unless otherwise specified in the inquiry and purchaseorder (see Supplementary Requirement S2), the choice ofstainless steel used shall be that of the fastener manufacturer asd
20、etermined by his fabrication methods and material availabil-ity. The specific stainless steel used by the manufacturer shallbe clearly identified on all certification required in the purchaseorder and shall have a chemical composition conforming to thelimits specified in Table 2.6.3 When chemical an
21、alysis is performed by the purchaserusing finished fasteners, the chemical composition obtainedshall conform to the limits specified in Table 2 for the specificalloy. Chemical composition shall conform to the tolerancesspecified in Specification A 555/A 555M.6.3.1 In the event of a discrepancy, a re
22、feree analysis of thesamples for each lot as specified in 12.1, shall be made inaccordance with 11.3.7. Mechanical Properties7.1 The finished screws shall conform to the mechanicalrequirements specified in Table 1.7.2 Screws having a nominal length equal to or greater thanthree diameters shall be te
23、nsile tested full size and shall meetthe full size breaking strength requirements specified in Table3. Tensile failures through the head are acceptable providingthe load requirements are satisfied.7.3 Screws that are too short (lengths less than specified in7.2 or that have insufficient threads for
24、tension testing) shallnot be subject to tension tests, but shall conform to thehardness requirements of Table 1.8. Corrosion Resistance Requirements Corrosion ResistanceRequirements8.1 Carbide Precipitation:8.1.1 Austenitic alloy rod, bar, and wire used to makefasteners in accordance with this speci
25、fication shall be capableof passing the test for susceptibility to intergranular corrosionas specified in Practice E of Practice A 262.8.1.2 As stated in Practices A 262, samples may be sub-jected to the faster and more severe screening test in accor-dance with Practice A. Failing Practice A, specim
26、ens shall betested to Practice E and be considered satisfactory if passingPractice E.8.1.3 If the fasteners pass the requirements of 8.1.1, theyshall be considered acceptable. If they fail, they shall be testedin accordance with Practice C of Practices A 262 and shallshow a corrosion rate not exceed
27、ing 0.05 mm/month.9. Dimensions9.1 Unless otherwise specified, the dimensions shall con-form to the requirements of ASME B 18.3.4M or ASMEB 18.3.5M, as specified.10. Workmanship, Finish, and Appearance10.1 Surface TreatmentUnless otherwise specified,screws shall be cleaned, descaled and passivated i
28、n accordancewith Practice A 380 or Specification A 967 at the option of themanufacturer.10.2 Surface Discontinuities:10.2.1 The surface discontinuities for these products shallconform to Specification F 788/F 788M and the additionallimitations specified herein.10.2.1.1 Forging defects that connect t
29、he socket to theperiphery of the head are not permissible. Defects originatingTABLE 1 Mechanical Property RequirementsProperty ClassNominal ThreadDiameterAFull SizeProduct TestsMachined Specimen Tests Core HardnessBTensileStrength, MPaMinimumExtensionCTensileStrength, MPaYield Strength,MPaElongation
30、,%, minVickers RockwellA1-50 M3M20 585 max 0.6D 585 max 380 max 40 210 max 95 HRB maxA155 M3M20 550 min 0.4D 550 min 270 min 25 160 min 50 HRA minA170 M3M20 700 min 0.4D 600 min 450 min 20 220 min 59 HRA minAActual full-size testing of Class A155 and A170 may result in decreased tensile strength bec
31、ause of the head configuration (see Table 3). For fasteners with nominalthread diameters larger than M20, the mechanical properties shall be agreed upon between the user and manufacturer.BCore hardness is only required when full-size product tensile testing cannot be accomplished.CD denotes nominal
32、thread size.F 879M 02a (2008)2on the periphery and with a traverse indicating a potential tointersect are not permissible. Other forging defects are permis-sible provided those located in the bearing area, fillet, and topsurfaces shall not have a depth exceeding 0.03 D or 0.13 mm,whichever is greate
33、r. For peripheral discontinuities, the maxi-mum depth may be 0.06 D (see Fig. 1).10.2.1.2 Forging defects located in the socket wall within0.1 times the actual key engagement, T, from the bottom of thesocket are not permissible. Discontinuities located elsewhere inthe socket shall not have a length
34、exceeding 0.25 T,oramaximum depth of 0.03 D not to exceed 0.13 mm (see Fig. 2).10.2.1.3 Seams in the shank shall not exceed a depth of 0.03D or 0.2 mm, whichever is greater.10.2.1.4 No transverse discontinuities shall be permitted inthe head-to-shank fillet area.10.2.1.5 Threads shall have no laps a
35、t the root or on theflanks, as shown in Fig. 3. Laps are permitted at the crests (Fig.3(c) that do not exceed 25 % of the basic thread depth, and onthe flanks outside the pitch cylinder. Longitudinal seams rolledbeneath the root of the thread and across the crests of thethreads are acceptable within
36、 the limits of 10.2.1.3.11. Number of Tests11.1 The requirements of this specification shall be met incontinuous mass production for stock and the manufacturershall make sample inspection to ensure that the productconforms to the specified requirements. Additional tests ofindividual shipments of fas
37、teners are not ordinarily necessary.A record of the individual heat of steel in each lot shall bemaintained. The containers shall be coded to permit identifi-cation of the lot.TABLE 2 Chemical RequirementsUNSDesignationAlloyComposition, % maximum except as shownCarbon Manganese Phosphorus Sulfur Sil
38、icon Chromium Nickel Copper MolybdenumS30400 304 0.08 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 10.5 1.00 . . .S30403 304L 0.030 2.00 0.045 0.030 1.00 18.0 to 20.0 8.0 to 12.0 1.00 . . .S30500 305 0.12 2.00 0.045 0.030 1.00 17.0 to 19.0 10.5 to 13.0 1.00 . . .S38400 384 0.08 2.00 0.045 0.030 1.00 15
39、.0 to 17.0 17.0 to 19.0 . . .S30430 189LW 0.10 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.00 to 4.00 . . .S30433 302HQ 0.03 2.00 0.045 0.030 1.00 17.0 to 19.0 8.0 to 10.0 3.0 to 4.0 . . .S31600 316 0.08 2.00 0.045 0.030 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.00S31603 316L 0.03 2.00 0.045 0.0
40、30 1.00 16.0 to 18.0 10.0 to 14.0 2.00 to 3.0TABLE 3 Breaking Strength Values for Full Size FastenersNOTE 1Breaking loads are based on tensile stress area and strengthsof 585 MPa max forA1-50, 550 MPa forA155, and 700 MPa minA1-70.The minimum loads for property classes A155 and A1-70 are reduced by2
41、0 % to allow for the head critical nature of these configurations. See NoteAinTable 1. Actual strength of the threaded section, if size permits, maybe determined by removing the head and testing the threaded section as astud.Nominal Size andThread PitchStress Area,mm2Property ClassA150 A155 A170kN,
42、max kN, min kN, minM3 3 0.5 5.03 2.94 2.21 2.82M4 3 0.7 8.78 5.14 3.86 4.92M5 3 0.8 14.2 8.30 6.24 7.94M6 3 1.0 20.1 11.8 8.9 11.3M8 3 1.25 36.6 21.4 16.1 20.5M10 3 1.5 58.0 33.9 25.5 32.5M12 3 1.75 84.3 49.3 37.1 47.2M14 3 2.0 115.0 67.5 50.8 64.6M16 3 2.0 157.0 91.7 68.9 87.7M20 3 2.5 245.0 143 10
43、8 137FIG. 1 Head Discontinuities (See 10.2.1)FIG. 2 Socket Discontinuities (See 10.2.1)F 879M 02a (2008)311.2 When specified in the purchase order, the manufacturershall furnish a test report of the last complete set of chemicalanalysis and mechanical tests for each stock size in eachshipment.11.3 W
44、hen tests of individual shipments are required,Supplementary Requirement S1 must be specified in theinquiry and order.11.3.1 When the purchaser does not specify the samplingplan and basis of acceptance, the following shall apply:11.3.1.1 The lot, for purposes of selecting samples, shallconsist of al
45、l products offered for inspection and testing at onetime, that are of the same type, style, nominal diameter, threadpitch, nominal length, material, property class, and surfacefinish.11.3.1.2 From each lot, samples shall be selected at randomand tested for each requirement in accordance with thefoll
46、owing:Number of Pieces in LotNumber ofSamples800 and less 1Over 800 to 8000, incl 2Over 8000 to 22 000, incl 3Over 22 000 511.3.1.3 Should any sample fail to meet the requirements ofa specified test, double the number of samples from the samelot shall be retested for the requirement(s) in which it f
47、ailed.All of the additional samples shall conform to the specificationor the lot shall be rejected.11.3.1.4 If the failure of a test specimen is due to improperpreparation of the specimen or an incorrect testing technique,the specimen shall be discarded and another test specimensubmitted.11.4 Corros
48、ion Resistance Tests:11.4.1 Unless otherwise specified, inspection for corrosionresistance shall be in accordance with the manufacturersstandard quality control practices. No specific method ofinspection is required but the screws shall be produced fromsuitable raw material and manufactured by prope
49、rly controlledpractices to maintain resistance to corrosion. When corrosiontests are required, Supplementary Requirement S4 must bespecified in the inquiry and order, except as noted in 11.4.2.11.4.2 Products that have been hot worked shall be solutionannealed and tested to determine freedom from precipitatedcarbides. Not less than one corrosion test shall be made fromeach lot. Corrosion tests shall be performed in accordance withPractices A 262, Practices A or E as applicable.12. Test Methods12.1 Chemical AnalysisThe chemical composition
