1、Designation: F835 12Standard Specification forAlloy Steel Socket Button and Flat Countersunk Head CapScrews1This standard is issued under the fixed designation F835; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last
2、revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () 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 fo
3、r quenchedand tempered alloy steel hexagon socket button (SBHCS)0.060 through 0.625 thread sizes and flat countersunk (SFHCS)0.060 through 1.5 thread sizes head cap screws having materialproperties for high-strength requirements.1.2 Fasteners meeting this specification are intended forshear-type app
4、lications and have tensile requirements rangingfrom 122 to 150 ksi.1.3 The values stated in inch-pound units are to be regardedas standard. No other units of measurement are included in thisstandard.1.4 The hazard statement applies only to the test methodsection, Section 11, of this specification. T
5、his standard doesnot 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 determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.
6、1 ASTM Standards:2A751 Test Methods, Practices, and Terminology for Chemi-cal Analysis of Steel ProductsD3951 Practice for Commercial PackagingE3 Guide for Preparation of Metallographic SpecimensE18 Test Methods for Rockwell Hardness of Metallic Ma-terialsE112 Test Methods for Determining Average Gr
7、ain SizeE384 Test Method for Knoop and Vickers Hardness ofMaterialsF606M Test Methods for Determining the MechanicalProperties of Externally and Internally Threaded Fasteners,Washers, and Rivets (Metric)F788/F788M Specification for Surface Discontinuities ofBolts, Screws, and Studs, Inch and Metric
8、Series2.2 ASME Standards:3B18.3 Socket Cap, Shoulder and Set ScrewsInch SeriesB18.24 Part Identifying Number (PIN) Code System Stan-dard for B18 Fastener Products3. Ordering Information3.1 Orders for material under this specification shall includethe following:3.1.1 Quantity (number of screws).3.1.2
9、 Dimensions, including nominal thread designation,thread pitch, and nominal screw length (inches). A standardpart 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 be specified
10、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.3.1.8 Any special requirements.3.1.9 For establishment of a part identifying system, seeASME B18.24.3.2 Example1000 pieces 0.250 20 3 0.375 S
11、BHCS lottensile test. ASTM F835XX.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 responsibility o
12、f Subcommittee F16.02 on Steel Bolts,Nuts, Rivets and Washers.Current edition approved May 1, 2012. Published June 2012. Originallyapproved in 1986. Last previous edition approved in 2004 as F835 041. DOI:10.1520/F0835-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontac
13、t 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 Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990,
14、http:/www.asme.org.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 tests on finished screws conducted in accordance withTest Methods E112 shall prevail.4.2 Scr
15、ews shall be hot or cold upset or extruded, or both.4.3 Unless otherwise specified, threads shall be rolled fordiameters through 0.625 in. and for screw lengths through 4 in.For diameters and lengths other than this, threads may berolled, cut or ground.4.4 Screws shall be heat treated by quenching i
16、n oil fromabove the transformation temperature and then tempering byreheating to at least 650F to be within the hardness rangespecified in Table 1.4.4.1 The minimum tempering temperature may be verifiedby submitting screws to 635F for 30 min at temperature. Theaverage cross-section hardness of three
17、 readings on the screwbefore and after retempering shall not differ by more than 20DPH.4.5 When protective or decorative coatings are applied tothe screws, precautions as required by the coatings shall betaken to prevent embrittlement.5. Chemical Composition5.1 The chemical composition of the screw
18、material shallconform to the heat analysis specified in Table 2.5.2 One or more of the following alloying elements, chro-mium, nickel, molybdenum, or vanadium, shall be present inthe steel in sufficient quantity to ensure the specific strengthproperties are met after oil quenching and tempering. The
19、 steelshall meet the AISI definition of alloy steel, that is, maximumand minimum element 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 purch
20、aser fromfinished products and the chemical composition thus deter-mined shall conform 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 length
21、equal to or greater than3 diameters shall be tested full size and shall conform to thefull-size tensile requirements specified in Table 3. Tensilefailures through the head are acceptable provided the loadrequirements are satisfied.6.3 Screws having a nominal thread diameter-length com-bination as sp
22、ecified in 6.2 and a breaking load exceeding200 000 lb 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-da
23、rd round machined specimens may be used that 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 th
24、ree timesnominal size) or that have insufficient threads for tensiontesting shall not be subject to tension tests but shall conform tothe hardness (minimum and maximum) requirements of Table1.6.5 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 dep
26、th 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 calcu
27、latedwith minimum screw tensile requirements.8. Dimensions8.1 Unless otherwise specified, the dimensions shall con-form to the requirements of ASME B 18.3.9. Workmanship, Finish, and Appearance9.1 Surface FinishThe screws shall have a black (thermalor chemical) oxide finish, unless otherwise specifi
28、ed.9.2 Surface Discontinuities:9.2.1 The surface discontinuities for these products shallconform to Specification F788/F788M and the additionallimitations specified herein.9.2.2 Forging defects that connect the socket to the periph-ery of the head are not permissible. Defects originating on theTABLE
29、 1 Mechanical RequirementsNominal Thread Size, in.0.500 andsmallerOver 0.500Full-size Screws:Tensile, min, ksi 145 135Machined Test Specimen:Yield strength at 0.2 % offset, min, ksiA153Tensile strength, min, ksiA170Elongation in 4D,min,%A8Reduction of area, min, %A35Product Hardness:Rockwell C 3944
30、3744Vickers DPH 382434 363434ANot applicable.TABLE 2 Chemical RequirementsElementComposition, %HeatAnalysisProductAnalysisCarbon 0.30 to 0.48 0.28 to 0.50Phosphorus, max 0.035 0.040Sulfur, max 0.040 0.045Alloying elements see 5.2 see 5.2F835 122periphery and with a traverse indicating a potential to
31、 intersectare not permissible. Other forging defects are permissible,provided those located in the bearing area, fillet and topsurfaces shall not have a depth exceeding 0.03 D or 0.005 in.,whichever is greater. For peripheral discontinuities, the maxi-mum depth may be 0.06 D not to exceed 0.040 in.
32、(seeFig. 2).9.2.3 Forging defects located in 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 or amaximum depth of 0.03 D not to exceed 0.005 in. (se
33、eFig. 3).9.2.4 Seams in the shank shall not exceed a depth of 0.03 Dor 0.008 in., whichever is greater.9.2.5 No transverse discontinuities 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 cr
34、est (Fig. 4c) thatdo not exceed 25 % 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 9.2.4.9.2.7 Quench cracks of any depth, any length, or in anyloc
35、ation are not permitted.10. Number of Tests10.1 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 m
36、aterial are not ordinarily contem-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.10.2 When specified in the order, the manufacturer shallfurnish a test report certified to be the last complete set ofm
37、echanical tests for each stock size in each shipment.10.3 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 diameterTABLE 3 Minimum Ultimate Tensile LoadsThread Size Stress Are
38、a, in.2Button and CountersunkHeads, Tensile Load,min lbACoarse Fine Coarse FineCoarseThreadSeriesFine ThreadSeries. . . 0.060-80 . . . 0.00180 . 2600.073-64 0.073-72 0.00263 0.00278 380 4000.086-56 0.086-64 0.00370 0.00394 540 5700.099-48 0.099-56 0.00487 0.00523 710 7600.112-40 0.112-48 0.00604 0.0
39、0661 880 9600.125-40 0.125-44 0.00796 0.00830 1150 12000.138-32 0.138-40 0.00909 0.01015 1320 14700.164-32 0.164-36 0.0140 0.10474 2030 21400.190-24 0.190-32 0.0175 0.0200 2540 29000.250-20 0.250-28 0.0318 0.0384 4610 52750.3125-18 0.3125-24 0.0524 0.0580 7600 84500.375-16 0.375-24 0.0775 0.0878 11
40、200 127000.4375-14 0.4375-20 0.1063 0.1187 15 400 170000.500-13 0.500-20 0.1419 0.1599 20 600 232000.625-11 0.625-18 0.226 0.258 30 500 345000.750-10 0.750-16 0.334 0.373 45 100 507000.875-9 0.875-14 0.462 0.509 62 400 692001.000-8 1.000-12 0.606 0.663 81 800 904001.125-7 1.125-12 0.763 0.858 103 00
41、0 1164001.250-7 1.250-12 0.969 1.073 131 000 1460001.375-6 1.375-12 1.155 1.315 156 000 1790001.500-6 1.500-12 1.405 1.581 190 000 215000ABecause of the head critical configuration of these parts, the full size tensile loads are based on 80 % of the minimum heat treated material strength (180 ksi fo
42、r sizes0.500 in. and smaller and 170 ksi for sizes larger than 0.500 in.) and the stress areas for coarse thread screws.TABLE 4 Decarburization LimitsThreads/in.ThreadHeight, hs0.75 hsfromRoot toCrest, min0.1 hsatRoot, max48 0.013 0.010 0.00144 0.014 0.011 0.00140 0.015 0.011 0.00236 0.017 0.013 0.0
43、0232 0.019 0.014 0.00228 0.022 0.017 0.00224 0.026 0.020 0.00320 0.031 0.023 0.00318 0.034 0.026 0.00316 0.038 0.029 0.00414 0.044 0.033 0.00413 0.047 0.035 0.00512 0.051 0.038 0.00511 0.056 0.042 0.00610 0.061 0.046 0.0069 0.068 0.051 0.0078 0.077 0.058 0.0087 0.088 0.066 0.0096 0.102 0.077 0.010F8
44、35 123and 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, incl 3Over 22 000 510.4 Should any sample fail to meet the requirements of aspecified test, double the numb
45、er 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 Methods11.1 Chemical analysis shall be conducted in accordancewith Test Methods, Practices, and Terminology
46、A751.11.2 Tensile properties shall be determined in accordancewith Test Methods F606M.11.3 Hardness shall be determined in accordance with TestMethods E18.11.4 Embrittlement tests shall be conducted in accordancewith Test Methods F606M. The countersunk washer for the flatcountersunk head cap screw s
47、hall be placed with the axis of theconical recess at the required wedge angle with the fasteneraxial load.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 withPrac
48、tice E3. Take measurements (1) at the 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 pitchFIG. 1 Decarburization LimitsFIG. 2 Head and Body Discon
49、tinuity LimitationsFIG. 3 Socket Discontinuity LimitationsF835 124line at a depth of 0.003 in. Use one of the two methods forcarburization/decarburization evaluation either optical 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 in0.001-in. increments. The width of any light etching bandnormally defines the decarburization depth.
