1、Designation: F 912 04e1Standard Specification forAlloy Steel Socket Set Screws1This standard is issued under the fixed designation F 912; 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 parent
2、heses 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 2006.1. Scope*1.
3、1 This specification covers the requirements for quenchedand tempered alloy steel socket-set screws (SSS) 0.060 through2.000-in. sizes having hardnesses 45 to 53 HRC.1.2 These set screws are intended for compression applica-tions only and are not customarily subjected to embrittlementtests. For tens
4、ile 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, associatedwith its use. It is the responsibili
5、ty of the user of this standardto establish appropriate safety and health practices anddetermine the applicability of regulatory limitations prior touse.NOTE 1Acomplete metric companion to Specification F 912 has beendevelopedF 912M; therefore, no metric equivalents are shown in thisSpecification.2.
6、 Referenced Documents2.1 ASTM Standards: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 Metalli
7、c MaterialsE112 Test Methods for Determining 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 Socket Cap, Shoulder and Set Screw, Inch Seri
8、es4B18.24 Part Identifying Number (PIN) Code System Stan-dard for B18 Fastener Products3. Ordering Information3.1 Orders for material under this specification shall includethe following information:3.1.1 Quantity (number of screws).3.1.2 Dimensions, including nominal thread designation,threads per i
9、nch, nominal screw length (inches) 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 10.3.3.1.6 Certification, if required. See 14.1.3.1.7 ASTM designation and year of is
10、sue.3.1.8 Any special or supplemental requirements.3.1.9 For establishment of a part identifying system, seeASME B18.24.4. Materials and Manufacture4.1 The screws shall be fabricated from alloy steel made tofine grain practice. In the event of controversy over grain size,referee tests on finished sc
11、rews conducted in accordance withTest Methods E112shall prevail.4.2 The screws 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 quenching in oil fromabove the transformation temperature a
12、nd 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; (1)1This specification is under the jurisdiction of AS
13、TM Committee 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 1986. Last previous edition approved in 2000 as F 912 00.2For referenced ASTM standards, v
14、isit the ASTM 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 Headquarter
15、s, Three Park 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 Conshohocke
16、n, PA 19428-2959, United States.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
17、be specified on the purchase order 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 s
18、crew material shallconform to the heat analysis specified in Table 1.5.2 One or more of the following alloying elements: chro-mium, nickel, molybdenum, or vanadium shall be present inthe steel in sufficient quantity to assure the specific strengthproperties are met after oil quenching and tempering.
19、 The steelshall meet the AISI definition of alloy steel, that is, maximumand minimum element content requirement or minimum ele-ment limits specified.5.3 Alloy steel to which bismuth, selenium, tellurium, orlead has been intentionally added to improve machinabilityshall be permitted.5.4 Material ana
20、lysis may be made by the purchaser fromfinished products and the chemical composition thus deter-mined shall conform 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 a
21、pplication of the testtightening torque specified 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 hardness limits shall apply throughout the screwfrom core to surface.7. Other Requirements7.1 Decarburization:7.1.1
22、 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, andin accordance with 11.4.8. Dimensions8.1 Unless
23、 otherwise specified, the product shall conform tothe requirements of ASME B 18.3.9. 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 additionallimitations specified herein.9.1.2 Pro
24、cessing defects that connect the socket to theperiphery of the screw are not permissible. Defects originatingon the periphery and with a traverse indicating a potential tointersect are not permissible.9.1.3 Quench cracks of any depth, any length, or in anylocation are not permitted.10. Number of Tes
25、ts10.1 The requirements of this specification shall be met incontinuous mass production for stock, and the manufacturershall make ample inspections to insure that the productconforms to the specified requirements. Additional tests ofindividual shipments of material are not ordinarily contem-plated.A
26、record 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 ofmechanical tests for each stock size in eac
27、h 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 diameterand length. From each lot, the number of samples for eachrequirement shall be as follows: (Note: This
28、will be alignedwith F 16.02 assurance decision.)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 number of samples from the same lotshall be reteste
29、d 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 A 751.11.2 For socket strength torque test, the
30、 test screw shall beassembled into a tapped hole of 2B tolerance class in a steelblock (see Fig. 2) until the face of the screw 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 applic
31、able hexagon key bit in accordancewith ASME B 18.3 shall be inserted to the full depth of the setscrew socket and the test torque listed in Table 2 applied bymeans of a torque wrench. The screw shall be disassembledfrom the block and examined for compliance to the require-ments of 6.1.11.3 Hardness
32、shall be determined in accordance with TestMethods E18.TABLE 1 Chemical RequirementsNOTE 1Plus alloys in accordance with 5.2.ElementComposition, %Heat Analysis Product AnalysisCarbon 0.30 to 0.48 0.28 to 0.50Phosphorus, max 0.035 0.040Sulfur, max 0.040 0.045F91204e1211.4 Decarburization and carburiz
33、ation tests shall be con-ducted as follows:11.4.1 Section the thread area of the screw longitudinallythrough the axis, mount, and polish it in accordance withPractice E3. Use one of the two methods for carburization ordecarburization evaluation: either optical or microhardnessmeasurements. The micro
34、hardness measurement shall consti-tute a referee method in case of dispute.11.4.2 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 etchin
35、g bandnormally defines the decarburization depth. A dark etchingband indicates the possibility of carburization.11.4.3 Measure microhardness in accordance with TestMethod E 384 on unetched specimens using a DPH 136indenter or a Knoop indenter using the following load appli-cation:Number of Threadspe
36、r inchLoadLess than 40 500 gf40, 44, and 48 200 gfOver 48 Use opticalevaluation in 11.4.211.4.3.1 Screw threads greater than 48 threads per inch,optical evaluation as described in 11.4.2 shall determineconformance to specification requirements. Take measure-ments at the minor diameter (Reading No. 1
37、) on the threadcrest bisector to determine base material hardness. Takemeasurements (Reading No. 2) on the bisector 0.75 h, from theminor measurement toward the thread crest. Also take mea-surements (Reading No. 3) on the thread flank at the pitch lineat a depth within 0.003 in. from the surface. Re
38、ading No. 3 maybe taken on the same or an adjacent thread.11.4.4 Interpret Microhardness Readings as Follows:11.4.4.1 A decrease of more than 30 hardness points fromReading No. 1 to Reading No. 2 shall be regarded asdecarburization and indicates the screw does not conform tospecification requirement
39、s.11.4.4.2 An increase of more than 30 hardness points fromReading No. 1 to Reading No. 3 shall be regarded asTABLE 2 Torsional Strength RequirementsNominalSizeShortest Nominal Screw Lengths Subject to Torque Testing for Test TorqueCup and FlatPointsCone andOval PointsHalf DogPointsin.-lb, min0 0.06
40、0 0.109 0.125 0.109 1.11 0.073 0.125 0.141 0.125 2.12 0.086 0.125 0.141 0.141 2.13 0.099 0.141 0.156 0.156 6.04 0.112 0.141 0.172 0.156 6.05 0.125 0.156 0.188 0.172 116 0.138 0.172 0.203 0.188 118 0.164 0.188 0.219 0.203 2310 0.190 0.188 0.250 0.234 4014 0.250 0.250 0.312 0.297 94516 0.312 0.312 0.3
41、91 0.359 18338 0.375 0.375 0.438 0.438 317716 0.437 0.438 0.547 0.484 50212 0.500 0.500 0.609 0.547 75058 0.625 0.625 0.766 0.672 146034 0.750 0.750 0.906 0.797 252078 0.875 0.875 1.125 0.984 57501 1.000 1.000 1.266 1.125 8000118 1.125 1.125 1.391 1.188 8000114 1.250 1.250 1.500 1.312 11 000138 1.37
42、5 1.375 1.656 1.438 11 000112 1.500 1.500 1.797 1.562 18 100134 1.750 1.750 2.219 1.953 38 0002 2.000 2.000 2.391 2.078 38 000TABLE 3 Decarburization LimitsThreads/in.ThreadHeight, hs0.75 hsfromRoot to Crest.min0.1 hsatRoot, max48 0.013 0.010 0.00144 0.014 0.011 0.00140 0.015 0.011 0.00236 0.017 0.0
43、13 0.00232 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
44、.0105 0.123 0.092 0.0124.5 0.136 0.102 0.0144 0.153 0.115 0.015F91204e13carburization 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-tur
45、ers works that concern the manufacture of the materialordered. The manufacturer shall afford the 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 by
46、the purchasers representative shall be made before shipment,and shall be so conducted as not to 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 reported
47、to the producer or supplier promptly and in writing. In case ofdissatisfaction with the results of the test, the producer orsupplier may make claim for a rehearing.14. Certification14.1 Upon request of the purchaser in the contract or order,a manufacturers certification that the material was manufac
48、-tured and tested in accordance with this specification, togetherwith a report of the latest 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 fasten
49、er to the purchaser.16. 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 shall include or be plainly markedwith the following information:16.2.1.1 ASTM designation,16.2.1.2 Size,16.2.1.3 Name and brand or trademark of the manufacturer,16.2.1.4 Number of pieces,16.2.1.5 Purchase order number, and16.2.1.6 Country of origin.
