WD955-20110429-穿透淬火自攻钉材料和性能要求-eng.pdf

WORLDWIDEFASTENERSTANDARD

2011-04-29

WD955

MATERIALANDPERFORMANCEREQUIREMENTS–THROUGHHARDENEDSPACEDTHREAD

TAPPINGSCREWS.

1.SCOPE:Thisstandardcoversmaterialandperformancerequirementsforthroughhardenedcarbonsteel

tappingscrews.Innormaluse,thesescrewsproducematingthreadsinmaterialsintowhichtheyaredriven

withoutdeformingtheirownthreads.Thisstandardisintendedtoproducescrewswithimprovedductility

whencomparedwiththecasehardenedscrewsproducedtoStandardWD950.

2.MATERIAL:Steel,Carbon0.15to0.35%,P0.035%max.,S0.035%max.Ifthecarboncontentisbelow0.25%,

withaboronaddition,theminimummanganesecontentshallbe0.7%..

3.MECHANICALPROPERTIES

3.1HEATTREATMENT:Screwsshallbehardenedandtemperedtoacorehardnessof320-380HV,(32-39

HRC).Thesurfacehardnessshallnotbemorethan30Vickerspointsabovethemeasuredcorehardnesson

theproductwhenreadingsofbothsurfaceandcorearecarriedoutatHV0.3.Anyincreaseinhardnessatthe

surfacewhichindicatesthatthesurfacehardnessexceeds390HVisnotacceptable.Thetempering

temperatureshallbe340oCmin.TherequirementsofWSS-M99A3-Ashallapply.

3.2HEADSOUNDNESS:Thereshallbenofractureatthehead/shankintersectionwhenapermanent

deformationof6oisinducedbetweentheplaneoftheunderheadbearingfaceandaplanenormaltotheaxis

ofthescrew.Thetestshallberegardedassatisfactoryevenifacrackshouldappearinthefirstthread,

providedthattheheaddoesnotsnapoff.Thistest