1、Designation: F 835M 04METRICStandard Specification forAlloy Steel Socket Button and Flat Countersunk Head CapScrews Metric1This standard is issued under the fixed designation F 835M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、the year of last revision. 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.1. Scope*1.1 This specification cove
3、rs the requirements for quenchedand tempered alloy steel hexagon socket button (SBHCS) andflat countersunk (SFHCS) head cap screws M3 through M20thread sizes having material properties of ISO 898/1 PropertyClass 12.9.1.2 Fasteners meeting this specification are intended forshear type applications an
4、d have tensile requirements equiva-lent to ISO 898/1 Property Class 10.9.1.3 The hazard statement pertains only to the test methodsection, Section 11 of this specification. This standard does notpurport to address all of the safety problems, if any, associatedwith its use. It is the responsibility o
5、f the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.2. Referenced Documents2.1 ASTM Standards:2A 751 Test Methods, Practices, and Terminology forChemical Analysis of Steel ProductsD 3951 Practice for Com
6、mercial PackagingE 3 Practice for Preparation of Metallographic SpecimensE 18 Test Methods for Rockwell Hardness and RockwellSuperficial Hardness of Metallic MaterialsE 112 Test Methods for Determining Average Grain SizeE 384 Test Method for Microindentation Hardness of Ma-terialsF 606M Test Methods
7、 for Determining the MechanicalProperties of Externally and Internally Threaded Fasteners,Washers, and Rivets MetricF 788/F 788M Specification for Surface Discontinuities ofBolts, Screws, and Studs, Inch and Metric Series2.2 ANSI/ASME Standards:B18.3.4M Hexagon Socket Button Head Cap Screws3B18.3.5M
8、 Hexagon Socket Flat Countersunk Head CapScrews3B18.24.1 Part Identifying Number (PIN) Code System42.3 ISO Standard:898/1 Mechanical Properties of Fasteners, Bolts, Screwsand Studs33. Ordering Information3.1 Orders for material under this specification shall in-clude:3.1.1 Quantity (number of screws
9、).3.1.2 Dimensions, including nominal thread designation,thread pitch and nominal screw length (millimetres). A stan-dard part number may be used for this definition.3.1.3 Name of the screw: SBHCS or SFHCS.3.1.4 Coating, if required. If a protective finish other thanblack oxide is required, it must
10、be specified on the order orproduct standard.3.1.5 Lot testing, if required (see 10.3).3.1.6 Certification, if required (see 14.1).3.1.7 ASTM designation and year of issue, and3.1.8 Any special requirements.3.1.9 For establishment of a part identifying system, seeASME B18.24.1.3.2 Example1000 pieces
11、 M6 3 1 3 25 SBHCS lot tensiletest, ASTM F 835M XX.4. Materials and Manufacture4.1 The screws shall be fabricated from alloy steel made tofine grain practice. In the event of controversy over grain size,1This specification is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct
12、 responsibility of Subcommittee F 16.02 on Steel Bolts,Nuts, Rivets, and Washers.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1983. Last previous edition approved in 2003 as F 835M 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orconta
13、ct 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 National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.4Available 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.referee test
15、s on finished screws conducted in accordance withTest Methods E 112 shall prevail.4.2 Screws shall be cold upset or extruded, or both.4.3 Screws shall be roll threaded.4.4 Screws shall be heat treated by quenching in oil fromabove the transformation temperature and then tempering byreheating to at l
16、east 380C to be within the hardness rangespecified in Table 1.4.4.1 The minimum tempering temperature may be verifiedby submitting screws to 370C for 30 min at temperature. Theaverage cross section hardness of three readings on the screwbefore and after retempering shall not differ by more than 20DP
17、H.4.5 When protective or decorative coatings are applied tothe screws, precautions as required by the coating, shall betaken to prevent embrittlement.5. Chemical Composition5.1 The chemical composition of the screw material shallconform to the heat analysis specified in Table 2.5.2 One or more of th
18、e following alloying elements, chro-mium, nickel, molybdenum, or vanadium, shall be present inthe steel in sufficient quantity to assure the specific strengthproperties are met after oil quenching and tempering. The steelshall meet the AISI definition of alloy steel, that is, maximumand minimum elem
19、ent content requirement or minimum ele-ment limits specified.5.3 Steel to which bismuth, selenium, tellurium, or lead hasbeen added intentionally shall not be permitted.5.4 Material analysis may be made by the purchaser fromfinished products and the chemical composition thus deter-mined shall confor
20、m to the requirements specified for theproduct analysis in Table 2.6. Mechanical Properties6.1 The finished screws shall conform to the mechanicalrequirements specified in Table 1.6.2 Screws having a nominal thread diameter-length com-bination equal to or greater than that in Table 1 of Test Methods
21、F 606M shall be tested full size and shall conform to the fullsize tensile requirements specified in Table 3. Tensile failuresthrough the head are acceptable provided the load requirementsare satisfied.6.3 Screws having a nominal thread diameter-length com-bination as specified in 6.2 and a breaking
22、 load exceeding 535kN preferably shall be tested full size and shall meet thefull-size tensile properties in Table 3. When equipment ofsufficient capacity for such tests is not available, or if excessivelength of the screws makes full-size testing impractical, stan-dard round machined specimens may
23、be used which shall meetthe “machined test specimen tensile properties” in Table 1. Ifdiscrepancy between full-size and machined specimen results,full-size tests shall be used as the referee method to determineacceptance.6.4 Screws that are too short (lengths less than that specifiedin 6.2 (see also
24、 Test Methods F 606M) or that have insufficientthreads for tension testing shall not be subject to tension testsbut shall conform to the hardness (minimum and maximum)requirements of Table 1.6.5 All screws, regardless of size, shall conform to thehardness specified in Table 1. Hardness shall be met
25、anywhereon the cross section through the threaded portion one diameterfrom the screw point.7. Other Requirements7.1 Decarburization:7.1.1 There shall be no evidence of carburization or grossdecarburization on the surfaces of the heat-treated screws whenmeasured in accordance with 11.5.7.1.2 The dept
26、h of partial decarburization shall be limited tothe values in Table 4 when measured as shown in Fig. 1, andin accordance with 11.5.7.2 EmbrittlementCoated screws shall withstand the em-brittlement test in accordance with 11.4 without showingindications of discontinuities. The loading shall be calcul
27、atedwith minimum screw tensile requirements.8. Dimensions8.1 Unless otherwise specified, the dimensions shall con-form to the requirements of ANSI/ASME B18.3.4M orB18.3.5M as specified.TABLE 1 Mechanical RequirementsFull-size Screws:Tensile, min, MPa 980Machined Test Specimen:Yield strength at 0.2 %
28、 offset, min, MPa 1100Tensile strength, min, MPa 1220Elongation in 5D, min, % 8Reduction of area, min, % 35Product Hardness:Rockwell 38 to 44 HRCVickers 372 to 434 DPHTABLE 2 Chemical RequirementsAElementComposition, %Heat Analysis Product AnalysisCarbon 0.30 to 0.48 0.28 to 0.50Phosphorus, max 0.03
29、5 0.040Sulfur, max 0.040 0.045ASee for alloy requirements.TABLE 3 Minimum Ultimate Tensile LoadsNOTE 1All values are rounded to 3 significant digits.Thread Size Stress Area, mm2Tensile Load, min,kNAM3 3 0.5 5.03 4.93M4 3 0.7 8.78 8.60M5 3 0.8 14.2 13.9M6 3 1 20.1 19.7M8 3 1.25 36.6 35.9M10 3 1.5 58.
30、0 56.8M12 3 1.75 84.3 82.6M14 3 2 115 109M16 3 2 157 155M20 3 2.5 245 240ABecause of the head critical configuration of these parts, the full-size tensileloads are based on 80 % of the machined specimen tensile strength and theapplicable stress areas. (Loads based on 980 MPa).F835M0429. Workmanship,
31、 Finish and Appearance9.1 Surface FinishThe screws shall have a black (thermalor chemical) oxide finish, unless otherwise specified.9.2 Surface Discontinuities:9.2.1 The surface discontinuities for these products shallconform to Specification F 788/F 788M and the additionallimitations specified here
32、in.9.2.2 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 intersectare not permissible. Other forging defects are permissibleprovided those located in the bearing area, fillet,
33、 and topsurfaces shall not have a depth exceeding 0.03 D or 0.13 m,whichever is greater. For peripheral discontinuities, the maxi-mum depth may be 0.06 D not to exceed 1 mm (see Fig. 2).9.2.3 Forging defects located in the socket wall within 0.1times the actual key engagement, T, from the bottom of
34、thesocket are not permissible. Discontinuities located elsewhere inthe socket shall not have a length exceeding 0.25 T,oramaximum depth of 0.03 D not to exceed 0.13 mm (see Fig. 3).9.2.4 Seams in the shank shall not exceed a depth of 0.03 Dor 0.2 mm, whichever is greater.9.2.5 No transverse disconti
35、nuities shall be permitted in thehead-to-shank fillet area.9.2.6 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 25 % of the basic thread depth, and on the flanksoutside the pitch cylinder. Longitudinal seams rol
36、led beneaththe root of the thread and across the crests of cut threads areacceptable within the limits of 9.2.4.9.2.7 Quench cracks of any depth, any length, or in anylocation are not permitted.10. Number of Tests10.1 The requirements of this specification shall be met incontinuous mass production f
37、or 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-plated. A record of individual heats of steel in each test lot shallbe maintained. The container
38、 shall be coded to permit identi-fication of the lot.10.2 When specified in the order, the manufacturer shallfurnish a test report certified to be the last complete set ofmechanical tests for each stock size in each shipment.10.3 When additional tests are specified on the purchaseorder, a lot, for p
39、urposes 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:Number of Pieces in LotNumber ofSamples800 and less 1Over 800 to 8000, incl 2Over 8000 to 22 000, i
40、ncl 3Over 22 000 510.4 Should any sample fail to meet the requirements of aspecified test, double the number of samples from the same lotshall be retested for the requirement(s) in which it failed. All ofthe additional samples shall conform to the specification or thelot shall be rejected.11. Test M
41、ethods11.1 Chemical analysis shall be conducted in accordancewith Test Methods, Practices, and Terminology A 751.11.2 Tensile properties shall be determined in accordancewith Test Methods F 606M.11.3 Hardness shall be determined in accordance with TestMethods E 18.11.4 Embrittlement tests shall be c
42、onducted in accordancewith Test Methods F 606M.11.5 Decarburization and carburization tests shall be con-ducted as follows:11.5.1 Section the thread area of the bolt longitudinallythrough the axis, mount, and polish it in accordance withPractice E 3. Take measurements (1) at the minor diameter inthe
43、 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 evaluation either optical
44、or mi-crohardness measurements. The microhardness measurementshall constitute a referee method in case of dispute.11.5.2 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 graduated in0.03-mm incr
45、ements. The width of any light etching bandnormally defines the decarburization depth. A dark etchingband indicates the possibility of carburization.11.5.3 Measure microhardness in accordance with TestMethod E 384 on unetched specimens using a DPH 136indenter or a Knoop indenter using the following
46、load appli-cation:Thread Pitch,P, min.LoadOver 0.6 500 gf0.6 200 gfLess than 0.6 Use optical evaluationin 11.5.2.11.5.3.1 Take measurements at minor diameter (ReadingNumber 1) on the thread crest bisector to determine base metalhardness. Take measurements (Reading Number 2) on thebisector 0.75 h fro
47、m the minor measurement toward the crest.Also take measurements (Reading Number 3) on the threadTABLE 4 Decarburization Limits for ThreadsAThread-Pitch,P,mmBasic ThreadHeight, hs=0.6135P mmN =34 hs,min, mmRoot = 0.1hs,mm0.7 0.429 0.322 0.0430.8 0.491 0.368 0.0491 0.613 0.460 0.0611.25 0.767 0.575 0.
48、0771.5 0.920 0.690 0.0921.75 1.074 0.806 0.1072 1.227 0.920 0.1232.5 1.534 1.151 0.153ASee Fig. 1.F835M043flank at the pitch line at a depth within 0.08 mm from thesurface. Reading Number 3 may be taken on the same or anadjacent thread.11.5.4 Interpret microhardness readings as follows:11.5.5 A decr
49、ease of more than 30 hardness points fromReading Number 1 to Reading Number 2 shall be regarded asdecarburization and indicates the screw does not conform tospecification requirements.11.5.6 An increase of more than 30 hardness points fromReading Number 1 to Reading Number 3 shall be regarded ascarburization and indicates that the screw does not conform tospecification requirements.12. Inspection12.1 The inspector representing the purchaser, upon reason-able notice, shall have free entry to all parts of the manufac-turers works that concern the manufacture of the mater
