1、Designation:F78813Standard 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 of revision,the year of
2、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 specification establishes allowabl
3、e 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 specification covers metric series products wi
4、th 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 the engineering requirements of the appli
5、cationnecessitate 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 that surface discontinuities on bolts,screw
6、s,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,screws,and studs with nominal diameters from
7、4to 24 mm inclusive,are essentially identical with requirementsgiven in ISO 6157/I.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 separately as standard.The values stated ineach system m
8、ay 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.2.Referenced Documents2.1 ASTM Standards:2E340 Test Method for Macroetching Metals and AlloysF1470 Practice for Fastener Sampl
9、ing for Specified Me-chanical Properties and Performance InspectionF1789 Terminology for F16 Mechanical Fasteners2.2 ISO Standard:3ISO 6157/I Fasteners,Surface Discontinuities on Bolts,Screws and Studs3.Ordering Information3.1 Orders for bolts,screws,and studs requiring disconti-nuity control shall
10、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 Discontinuities(see TerminologyF1789 for definitions not provided)4.1 Crack4.1.1 Quench
11、 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.Limits arespecified in 5.4.4.2.1 Shear BurstA shear burst is an open break in themetal locate
12、d at approximately a 45 angle to the product axis.Shear bursts occur most frequently at the periphery of productshaving flanged or circular heads.Shear bursts may also occuron the sides of hex-head products.Typical shear bursts areshown in Fig.3.Limits are specified in 5.4.1This specification is und
13、er the jurisdiction of ASTM Committee F16 onFasteners and is the direct responsibility of Subcommittee F16.93 on QualityAssurance Provisions for Fasteners.Current edition approved April 1,2013.Published April 2013.Originallyapproved in 1982.Last previous edition approved in 2012 as F788 12.DOI:10.15
14、20/F0788-13.2For 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 ASTM website.3Available from American National Standards Institute(
15、ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 4.3 SeamTypical seams are shown in Fig.4.Limits arespecifi
16、ed in 5.5.4.4 FoldTypical folds are shown in Fig.5 a,b,and c.Limits are specified in 5.6.4.5 Thread 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 planished during forging.Typical voids are shown in Fig.6.Limits are specified in 5.7.4.7 Tool MarksTool m
