ENGINEERINGMaterialSpecification

GM6102M

STANDARDSMetals

SurfaceDiscontinuitiesonBoltsandScrews

1Scopeboundaries.Cracksarenormallycausedby

overstressingthemetalduringforgingorother

Thisstandarddefines,illustratesandspecifies

formingoperations,orduringheattreatment.

allowablelimitsforthevarioustypesofsurface

Wherepartsaresubjectedtosignificantreheat-

discontinuitiesthatmayoccurduringthemanu-

ing,cracksareusuallydiscoloredbyscale.

factureandprocessingofbolts,screws,and

studs,includingheattreatedmachinescrews,3.1.1.1Quenchcracksmayoccurduringheat

tappingscrews,andscrewandwasherassem-treatmentduetoexcessivelyhighthermaland

blies(thewashercomponentsofassembliesaretransformationstresses.Quenchcracksusually

excluded).Thisspecificationcoversfastenersintraverseanirregularanderraticcourseonthe

sizes5to24mm(No.12to1inch),inclusive,surfaceoftheboltorscrew.Typicalquench

withlengthsupto150mm,inclusive,andwithcracksareshowninFigure1.

specifiedminimumtensilestrengthof830MPa3.1.1.2