1、Designation: F788 13 (Reapproved 2018)Standard Specification forSurface Discontinuities of Bolts, Screws, and Studs, Inchand Metric Series1This standard is issued under the fixed designation F788; the number immediately following the designation indicates the year of originaladoption or, in the case
2、 of revision, the year of last 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 U.S. Department of Defense.1. Scope*1.1 This spec
3、ification establishes allowable limits for thevarious types of surface discontinuities that may occur duringthe manufacture and processing of bolts, screws, and studs,including heat-treated machine screws, tapping screws, andsems (the washers of screw-washer assemblies are excluded).This specificati
4、on covers metric series products with nominaldiameters of 4 mm and larger and with specified minimumtensile strengths of 420 MPa and higher; and inch seriesproducts with nominal diameters of No. 5 (0.1250 in.) andlarger and with specified minimum tensile strengths of 60 000psi and higher.1.2 When th
5、e engineering requirements of the applicationnecessitate control of surface discontinuities on bolts, screws,or studs, the purchaser shall specify conformance to ASTMSpecification F788, in the original inquiry and purchase order.1.2.1 When the engineering requirements of the applicationnecessitate t
6、hat surface discontinuities on bolts, screws, andstuds be controlled within limits closer than those specified inthis specification, the purchaser shall specify the applicablelimits in the original inquiry and purchase order.1.3 The allowable limits established in this specification formetric bolts,
7、 screws, and studs with nominal diameters from 4to 24 mm inclusive, are essentially identical with requirementsgiven in ISO 6157I. There are no ISO standards for surfacediscontinuities on any inch-series products.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separate
8、ly as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This international standard was developed in accor-dance with internat
9、ionally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2E340 Pra
10、ctice for Macroetching Metals and AlloysF1470 Practice for Fastener Sampling for Specified Me-chanical Properties and Performance InspectionF1789 Terminology for F16 Mechanical Fasteners2.2 ISO Standard:3ISO 6157I Fasteners, Surface Discontinuities on Bolts,Screws and Studs3. Ordering Information3.1
11、 Orders for bolts, screws, and studs requiring disconti-nuity control shall include the following:3.1.1 ASTM designation and date of issue of this specifica-tion.3.1.2 Special requirements, for example, closer discontinu-ity limits (1.2.1) and inspection sampling plan (6.2).4. Types of Surface Disco
12、ntinuities (see TerminologyF1789 for definitions not provided)4.1 Crack4.1.1 Quench CracksTypical quench cracks are shown inFig. 1. Limits are specified in 5.2.4.1.2 Forging CracksTypical forging cracks are shown inFig. 2. Limits are specified in 5.3.4.2 BurstTypical bursts are shown in Fig. 3. Limi
13、ts arespecified in 5.4.1This specification is under the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.93 on QualityAssurance Provisions for Fasteners.Current edition approved Sept. 1, 2018. Published September 2018. Originallyapproved in 1982. La
14、st previous edition approved in 2013 as F788 13. DOI:10.1520/F0788-13R18.2For referenced ASTM standards, visit 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 A
15、STM website.3Available from International Organization for Standardization (ISO), ISOCentral Secretariat, BIBC II, Chemin de Blandonnet 8, CP 401, 1214 Vernier,Geneva, Switzerland, http:/www.iso.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Ba
16、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom
17、mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.14.2.1 Shear BurstA shear burst is an open break in themetal located at approximately a 45 angle to the product axis.Shear bursts occur most frequently at the periphery of productshaving flanged or circular
18、 heads. Shear bursts may also occuron the sides of hex-head products. Typical shear bursts areshown in Fig. 3. Limits are specified in 5.4.4.3 SeamTypical seams are shown in Fig. 4. Limits arespecified in 5.5.4.4 FoldTypical folds are shown in Fig. 5 a, b, and c.Limits are specified in 5.6.4.5 Threa
19、d LapLimits are specified in SupplementaryRequirement S.1.1.4.6 VoidA void is a shallow pocket or hollow on thesurface of a bolt or screw due to nonfilling of metal duringforging. Voids are produced by marks or impressions of chips(shear burrs) or by rust formation on the raw material. They arenot p
20、lanished during forging. Typical voids are shown in Fig.6. Limits are specified in 5.7.4.7 Tool MarksTool marks are longitudinal or circumfer-ential grooves of shallow depth produced by the movement ofmanufacturing tools over the surface of the bolt or screw.Typical tool marks are shown in Fig. 7. L
21、imits are specified in5.8.4.8 Gouge and Nickan indentation on the surface of afastener produced by impact with another fastener, or fromprocessing equipment during manufacture, handling or trans-port.5. Allowable Limits5.1 Letter DefinitionsThroughout the followingrequirements, D designates the nomi
22、nal size (basic majordiameter of thread) of bolts, screws, and studs, except forproducts with shoulders, in which case D designates the largestshoulder diameter; and Dc designates flange diameter (speci-fied maximum) or head diameter (specified maximum) ofcircular head products. For metric series pr
23、oducts, D and Dcare in millimetres; for inch-series products, D and Dc are ininches.5.2 Quench CracksQuench cracks of any depth, anylength, or in any location are not permitted.5.3 Forging CracksForging cracks on the top of the headof bolts and screws are permitted, provided that (a) no crackshall h
24、ave a length exceeding 1.0 D, and ( b) no crack shallhave a width or depth exceeding 0.04 D. See Note 1.NOTE 1Forging cracks within the limits of this specification may beunsightly, but do not affect the mechanical properties or functionalrequirements of the bolt.5.4 Bursts and Shear Bursts (see Not
25、e 2):5.4.1 For hex-head bolts and screws, bursts and shear burstsare permitted, provided that: (1) no burst or shear burst in theflats extends into the crown (chamfer) circle on the top of thehead or into the underhead bearing circle, (2) no burst or shearburst located at the intersection of two wre
26、nching flats reducesthe width across corners below its specified minimum, and (3)no burst or shear burst has a width or depth greater than .06Dbut not to exceed .062 in. (1.6 mm).5.4.2 For flange bolts and screws and products with circularheads, bursts and shear bursts at the periphery of the flange
27、 orhead are permitted, provided that: (1) not more than one burstor shear burst has a width greater than 0.04 Dc, and (2) thewidth of the one burst or shear burst that exceeds a width of0.04 Dc does not have a width greater than 0.08 Dc.5.4.3 For indented head bolts and screws, bursts and shearburst
28、s in the raised periphery of the indented head arepermitted, provided that: (1) no burst or shear burst has a widthFIG. 1 Typical Quench CracksFIG. 2 Typical Forging CracksF788 13 (2018)2greater than 0.06 D, and (2) no burst or shear burst has a depthextending below the indented portion.NOTE 2Bursts
29、 and shear bursts within the limits of this specificationmay be unsightly, but do not affect the mechanical properties or functionalrequirements of the bolt.5.5 Seams:FIG. 3 Typical Bursts and Shear BurstsFIG. 4 Typical SeamsFIG. 5 Typical FoldsF788 13 (2018)35.5.1 Seams in the shanks of bolts, scre
30、ws, and studs arepermitted provided that no seam has a depth greater than 0.03D.5.5.2 Seams extending into the heads and flanges of boltsand screws are permitted, provided that they do not openbeyond the limits specified for bursts and shear bursts in 5.4.5.6 Folds:5.6.1 Folds located at interior co
31、rners that are at or belowthe underhead bearing surface, for example, at the junction ofhead to shank, are not permitted, except for cloverleaf foldsoccurring at the intersection of non-circular shoulders withhead bearing face (see Fig. 5a).5.6.2 Folds located at interior corners that are above theu
32、nderhead bearing surface, for example, at the junction of thehex head with the top of flange of flange bolts and screws, arepermitted (see Fig. 5 b).5.6.3 Folds located at exterior corners are permitted (seeFig. 5c).5.7 Voids:5.7.1 Voids on the surfaces of bolts, screws, and studs arepermitted, prov
33、ided that: (1) depth of voids does not exceed0.25 mm or 0.010 in. or 0.02 D, whichever is greater, and (2)the combined area of all voids on the underhead bearingsurface of bolts and screws does not exceed 10 % of thespecified minimum bearing surface area.5.7.2 The method for determining the area of
34、voids on thebearing surface shall be as agreed upon between the purchaserand the producer.5.8 Tool Marks:5.8.1 Tool marks on the underhead bearing surface arepermitted, provided the surface roughness measurement doesnot exceed 3.2 m or 125 in., determined as the arithmeticaverage deviation from the
35、mean surface.5.8.2 Tool marks on other surfaces of the product arepermitted.5.9 Nicks and GougesNicks, gouges, dents, and scrapesare permitted, provided that the functionability of the productis not impaired.6. Inspection and Evaluation6.1 Bolts, screws, and studs shall be inspected for surfacedisco
36、ntinuities in accordance with the procedure in 6.2, 6.3,and 6.4.FIG. 6 Typical VoidsFIG. 7 Typical Tool MarksTABLE 1 Bolt and Screw Thread Discontinuity Acceptance CriteriaInch Fasteners Metric FastenersSizeNominalDiameter (d)in.AllowableTorque SizeNominalDiameter (d)mmAllowableTorquein. lb ft. lb N
37、m#10 0.190 1.0 M5 5 0.1#12 0.216 1.5 M6 6 0.214 0.250 2.5 M8 8 0.5516 0.312 4.5 M10 10 1.038 0.375 7.5 M12 12 1.7716 0.438 1.0 M14 14 2.712 0.500 1.5 M16 16 4.1916 0.563 2.2 M18 18 5.858 0.625 3.0 M20 20 8.034 0.750 5.1 M22 22 10.678 0.870 8.1 M24 24 13.81 1.000 12.1 M30 30 27.0118 1.125 17.2 M33 33
38、 36.0114 1.250 23.6 M36 36 46.6138 1.375 31.4 . . .112 1.500 40.8 . . .Formula T = 145d3T = 145d3/12 Formula T = 0.001d3F788 13 (2018)46.2 The purchaser shall specify in the original inquiry andpurchase order the inspection sampling requirements that theproducer must satisfy to demonstrate the accep
39、tability of bolts,screws, and studs with respect to surface discontinuities.6.3 In the absence of purchaser instructions (6.2), inspectionand evaluation shall be in accordance with 6.5.6.4 For referee purposes, unless other procedures have beenspecified by the purchaser (6.2), inspection and evaluat
40、ion shallbe in accordance with 6.5.6.5 Inspection Procedure:6.5.1 Visual Inspection:6.5.1.1 A random sample shall be taken from the lot inaccordance with Guide F1470 and examined visually (mag-netic particle or fluid penetrant are recommended) for thepresence of quench cracks, forging cracks, bursts
41、, shear bursts,seams, folds, voids, tool marks, and nicks and gouges. Visualinspection can include the use of devices that provide up to,and including, 10-power magnification.6.5.1.2 If, during this inspection, any products are foundwith quench cracks in any location or with folds at interiorcorners
42、 that are at or below the underhead bearing surface, thelot may be rejected by the purchaser.6.5.1.3 If, during this inspection, any products are foundwith any other surface discontinuity, each discontinuity shallbe measured, and if any is found that exceeds the allowabledimensional limits for that
43、discontinuity as specified inSection5, the lot may be rejected by the purchaser.6.5.1.4 When a GO ring gage will not assemble the fullthread length of an externally threaded fastener when torque isapplied by hand, whether due to surface discontinuities orcoating buildup, or both, the following proce
44、dure shall be usedto determine thread acceptability. Using an appropriatelycalibrated torque measuring device and an appropriately cali-brated GO ring gage (class 3A for inch and 6h for metricfasteners) either hold the ring gage or the bolt stationary androtate the other the full length of the bolt
45、thread. Record themaximum torque observed. Nicks, gouges, or accumulation ofcoating materials shall not interfere with hand assembly ofinitial thread engagement or impair product function. Nolubricant shall be added to the bolt or gage for purposes ofconducting the test. The indicated maximum torque
46、 value shallnot exceed those in Table 1 that are derived the indicatedformula.7. Keywords7.1 bolts; crack; discontinuities (surface); fold; screw(machine, sems, tapping); seam; studs; thread lap; voidSUPPLEMENTARY REQUIREMENTSOne or more of the following supplementary requirements shall apply only w
47、hen specified by thepurchaser in the inquiry and order. Supplementary Requirements shall in no way negate anyrequirement of the specification itself.S1. Assemblies Subject to Severe Dynamic StressesS1.1 Laps in Screw Threads:S1.1.1 Laps of any depth and any length which originatebelow (or originatin
48、g above and extending below) a pointlocated at a distance equal to or less than 20 % of the threadheight, measured from the minor diameter, are not permitted.See 4.5 and the Fig. S1.1 and Fig. S1.2.S1.1.2 Surface discontinuities of threads caused by thethread rolling process, as in Fig. S1.2, shall
49、be excluded fromthese requirements provided the discontinuities do not exceedthe depth of 0.5 % nominal diameter and are essentiallyparallel to the adjacent thread contour and are not directedtoward the screw or bolt axis.S1.2 Thread Lap Inspection:S1.2.1 Visual InspectionA random sample shall be se-lected from the lot in accordance with F1470. The sampleselected shall be surface etched in a 50 % solution of HCl andH2O at approximately 180F (no more than 5 min of etch timeshould be employed as excessive etching may remove shallowthread la
