1、Designation: F 912M 04e1METRICStandard Specification forAlloy Steel Socket Set Screws Metric1This standard is issued under the fixed designation F 912M; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber 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.e1NOTESections 2.2 and 3.1.9 were editorially revised in October 2
3、006.1. Scope*1.1 This specification covers the requirements for quenchedand tempered alloy steel socket set screws (SSS) M1.6 throughM24 sizes having hardnesses 45 to 53 HRC, ISO 898/5property class 45H.1.2 These set screws are intended for compression applica-tions only and are not customarily subj
4、ected to embrittlementtests. For tensile applications, consult with the manufacturerfor proper alloy and hardness.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 concerns, if any, associate
5、dwith its use. It is the responsibility of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.NOTE 1This specification is the metric companion of SpecificationF 912.2. Referenced Documents2.1 ASTM Standar
6、ds:2A 751 Test Methods, Practices, and Terminology forChemical Analysis of Steel ProductsD 3951 Practice for Commercial PackagingE3 Guide for Preparation of Metallographic SpecimensE18 Test Methods for Rockwell Hardness and RockwellSuperficial Hardness of Metallic MaterialsE112 Test Methods for Dete
7、rmining Average Grain SizeE 384 Test Method for Microindentation Hardness of Ma-terialsF 788/F 788M Specification for Surface Discontinuities ofBolts, Screws, and Studs, Inch and Metric Series2.2 ASME Standards:3B18.3.6M Hexagon Socket Set Screws Metric SeriesB18.24 Part Identifying Number (PIN) Cod
8、e System Stan-dard for B18 Fastener Products2.3 ISO Standard:898/5 Mechanical Properties of FastenersSet Screws andSimilar Threaded Fasteners Not Under Tensile Stress43. Ordering Information3.1 Orders for material under this specification shall includethe following information:3.1.1 Quantity (number
9、 of screws).3.1.2 Dimensions, including nominal thread designation,thread pitch, nominal screw length (millimetres) and pointconfiguration. A standard part number may be used for thisdefinition.3.1.3 Name of the screw (SSS).3.1.4 Coating, if required. See 4.4.3.1.5 Lot testing, if required. See 10.3
10、.3.1.6 Certification, if required. See 14.1.3.1.7 ASTM designation and year of issue.3.1.8 Any special or supplemental requirements.3.1.9 For establishment of a part identifying system, seeASME B18.24.3.2 Example50 000 pieces M6x1x8 cone point SSScertification per 14.1ASTM F 912M_ _(state issue date
11、), or25000 pcs B1836A 060008K SSScertification per 14.1ASTM F 912M _ _(state issue date).4. Material and Manufacture4.1 The screws shall be fabricated from alloy steel made toa fine grain practice. In the event of controversy over grain1This specification is under the jurisdiction of ASTM Committee
12、F16 onFasteners and is the direct responsibility of Subcommittee F16.02 on Steel Bolts,Nuts, Rivets, and Washers.Current edition approved Aug. 1, 2004. Published August 2004. Originallyapproved in 1985. Last previous edition approved in 2000 as F 912M 00.2For referenced ASTM standards, visit the AST
13、M website, www.astm.org, orcontact 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 Par
14、k Ave., New York, NY 10016-5990.4Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York, NY 10036.1*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-
15、2959, United States.size, referee tests on finished screws conducted in accordancewith Test Methods E112shall prevail.4.2 The screw may be forged, formed, extruded, machined,or ground to meet the dimensional characteristics and perfor-mance requirements.4.3 Set screws shall be heat treated by quench
16、ing in oil fromabove the transformation temperature and then tempered byreheating to meet the hardness range specified in 6.2.4.4 Standard FinishesUnless otherwise specified, thescrews shall be furnished with one of the following standardsurfaces as manufactured, at the option of the manufacturer; (
17、1)bright uncoated; (2) thermal black oxide; or (3) chemical blackoxide. Hydrogen embrittlement tests shall not be required forscrews furnished in these conditions.4.5 Protective Coatings:4.5.1 When a protective finish other than as specified in 4.4is required, it shall be specified on the purchase o
18、rder with theapplicable finish specification.4.5.2 When protective or decorative coatings are applied tothe screws, precautions specified by the coating requirementsto minimize embrittlement shall be exercised.5. Chemical Composition5.1 The chemical composition of the screw material shallconform to
19、the heat analysis specified in Table 1.5.2 One or more of the alloying elements chromium, nickel,molybdenum, or vanadium shall be present in the steel insufficient quantity to assure that specific strength properties aremet after oil quenching and tempering. The steel shall meet theAISI definition o
20、f alloy steel, that is, maximum and minimumelement content requirement or minimum element limits speci-fied.5.3 Alloy steel to which bismuth, selenium, tellurium, orlead has been intentionally added to improve machinabilityshall be permitted.5.4 Material analysis may be made by the purchaser fromfin
21、ished products and the chemical composition thus deter-mined shall confirm to the requirements specified for theproduct analysis in Table 1.6. Mechanical Properties6.1 Socket set screws when subjected to a torque test inaccordance with 11.2 shall withstand application of the testtightening torque sp
22、ecified in Table 2 without evidence of thesocket reaming or the screw bursting.6.2 Socket set screws shall have a hardness of 45 to 53HRC. The point end hardness within 0.04 mm distance fromthe surface shall be equal to or greater than the measured corehardness but shall not exceed 53 HRC (560 DPH).
23、7. Other Requirements7.1 Decarburization:7.1.1 There shall be no evidence of gross decarburization ofthe surfaces of the heat-treated screws when measured inaccordance with 11.4.7.1.2 The depth of partial decarburization shall be limited tothe values in Table 3 when measured as shown in Fig. 1. andi
24、n accordance with 11.4.8. Dimensions8.1 Unless otherwise specified, the product shall conform tothe requirements of ASME B18.3.6M.9. Workmanship, Finish, and Appearance9.1 Surface Discontinuities:9.1.1 The surface discontinuities for these products shallconform to Specification F 788/F 788M and the
25、additionallimitations specified herein.9.1.2 Processing defects that connect the socket to theperiphery of the screw are not permissible. Defects originatingTABLE 1 Chemical RequirementsNOTE 1Plus alloys in accordance with 5.2.Element Composition, %Heat Analysis Product AnalysisCarbon 0.30 to 0.48 0
26、.28 to 0.50Phosphorus, max 0.035 0.040Sulfur, max 0.040 0.045TABLE 2 Torsional Strength RequirementsNominalScrewSizeShortest Nominal ScrewLengths Subject to TorqueTesting forTestTorqueN-m,minCup andFlatPointsCone andOvalPointsHalfDogPoints1.6 3 3 3 0.124440.22.5 4 4 4 0.634551.04566255884766 .8 8 10
27、 10 17.810 10 12 12 3512 12 16 16 5716 16 20 20 12620 25 25 25 25224 25 30 30 420TABLE 3 Decarburization Limits for ThreadsAThread Pitch,P,mmBasic ThreadHeight, h =0.6135P mmN =3/4hmin,mmRoot,0.1 h,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 0.0771.5 0.920 0.690 0
28、.0921.75 1.074 0.806 0.1072 1.227 0.920 0.1232.5 1.534 1.151 0.1533 1.840 1.380 0.1843.5 2.147 1.610 0.2154 2.454 1.841 0.2454.5 2.761 2.071 0.2765 3.068 2.301 0.307ASee Fig. 2.F912M04e12on the periphery and with a traverse indicating a potential tointersect are not permissible.9.1.3 Threads shall h
29、ave no laps at the root or on the flanks,as shown in Fig. 2(a). Laps are permitted at the crest (Fig. 2(c)that do not exceed 25 % of the basic thread depth and on theflanks outside the pitch cylinder. Longitudinal seams rolledbeneath the root of the thread and across the crests of cutthreads are acc
30、eptable within the limits of 0.03 D or 0.2 mm,whichever is greater.9.1.4 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 for stock, and the manufacturershall make samp
31、le inspections to ensure that the productconforms to the specified requirements. Additional tests ofindividual shipments of material 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 th
32、e 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 purposes of selecting test samples, shall consis
33、tof 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 Lot Number of Samples800 and less 1Over 800 to 8000, incl 2Over 8000 to 22 000, incl 3Over 22 000 510.4 Should any sample fail
34、 to meet the requirements of aspecified test, double the number of samples from the same lotFIG. 1 Decarburization LimitsFIG. 2 Thread DiscontinuitiesF912M04e13shall be retested for the requirement(s) in which it failed.All ofthe additional samples shall conform to the specification or thelot shall
35、be rejected.11. Test Methods11.1 Chemical analysis shall be conducted in accordancewith Test Methods, Practices, and Terminology A 751.11.2 For socket strength torque test, the test screw shall beassembled into a tapped hole of 5H tolerance class in a steelblock (see Fig. 3) until the face of the sc
36、rew is flush with thetop surface of the test block and the set screw bears against afirm base, such as a hardened screw installed from the oppositeside of the block. The applicable hexagon key bit shall beinserted to the full depth of the set screw socket and the testtorque listed in Table 2 applied
37、 by means of a torque wrench.The screw shall be disassembled from the block and examinedfor compliance to the requirements of 6.1.11.3 Hardness shall be determined in accordance with TestMethods E18.11.4 Decarburization Tests Shall be Conducted as Follows:11.4.1 Section the thread area of the screw
38、longitudinallythrough the axis, mount, and polish it in accordance withPractice E3. Take measurements (1) at the minor diameter inthe center of the thread ridge, (2) 0.75 h toward the thread creston the perpendicular bisector of the thread ridge, (3)onthethread flank approximately at the pitch line
39、at a depth of 0.08mm, and (4) in the thread root at a depth of 0.1 h. Use one ofthe two methods for decarburization evaluation, either opticalor microhardness measurements. The microhardness measure-ment shall constitute a referee method in case of dispute.11.4.2 For optical measurement, etch the se
40、ction in 2 4 %nital. Examine the surface of the etched samples under amicroscope at 1003 using a measuring eyepiece graduated in0.03-mm increments. The width of any light etching bandnormally defines the decarburization depth. A dark etchingband indicates the possibility of carburization.11.4.3 Meas
41、ure microhardness in accordance with TestMethod E 384 on unetched specimens using a DPH 136indenter or a Knoop indenter using the following load appli-cation:Thread Pitch, P, min. LoadOver 0.6 500 gf0.6 200 gfLess than 0.6 Use optical evaluation in 11.4.211.4.3.1 Screw threads greater than 48 thread
42、s per inch,optical evaluation as described in paragraph 11.4.2 shalldetermine conformance to specification requirements. Takemeasurements at minor diameter (Reading No. 1) on the threadcrest bisector to determine base material hardness. Takemeasurements (Reading No. 2) on the bisector 0.75 h, from t
43、heminor measurement toward the thread crest. Also take mea-surements (Reading No. 3) on the thread flank at the pitch lineat a depth within 0.08 mm from the surface. Reading No. 3may be taken on the same or an adjacent thread.11.4.4 Interpret Microhardness Readings as Follows:11.4.4.1 A decrease of
44、more than 30 hardness points fromReading No. 1 to Reading No. 2 shall be regarded asdecarburization and indicates the screw does not conform tospecification requirements.11.4.4.2 An increase of more than 30 hardness points fromReading No. 1 to Reading No. 3 shall be regarded ascarburization and indi
45、cates 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 materialordered. The manufacturer shall afford t
46、he inspector all rea-sonable facilities to satisfy him that the material is beingfurnished in accordance with this specification. All tests andinspections required by the specification that are requested bythe purchasers representative shall be made before shipment,and shall be so conducted as not t
47、o interfere unnecessarily withthe operation of the works.13. Rejection and Rehearing13.1 Material that fails to conform to the requirements ofthis specification may be rejected. Rejection should be reportedto the producer or supplier promptly and in writing. In case ofdissatisfaction with the result
48、s of the test, the producer orsupplier may make claim for a rehearing.14. Certification14.1 Upon request for the purchaser in the contract or order,a manufacturers certification that the material was manufac-tured and tested in accordance with this specification, togetherwith a report of the latest
49、mechanical tests of each stock size ineach shipment, shall be furnished at the time of shipment.15. Responsibility15.1 The party responsible for the fastener shall be theorganization that supplies the fastener to the purchaser.FIG. 3 Typical Torque Test FixtureF912M04e1416. Packaging and Package Marking16.1 Packaging:16.1.1 Unless otherwise specified, packaging shall be inaccordance with Practice D 3951.16.1.2 When special packaging requirements are required,they shall be defined at the time of the inquiry and order.16.2 Package Marking:16.2.1 Each shipping unit
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