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1、热处理后金属表面硬度概念Theabilityofmetalmaterialstoresistthepressingofotherhardobjectsintothesurfaceiscalledhardness,ortheresistanceofthematerialtotheplasticdeformationofthepart・Therefore,hardnessandstrengthhaveacertainrelationship・Accordingtothemethodofhardnessmeasurement,mainlycanbedividedi
2、nto:(1)Brinellhardness(codeHB);WithadiameterofDhardenedsteelballinPunderthespecifiedloadispressedintothesurfaceofthespecimenremainedafteraperiodoftimetoremovetheload,willstayinthesurfaceofthespecimensurfaceofFindentation,tothespecimenperunitsurfaceareacanwithstandtheloadoftherepres
3、entationofthespecimenhardness:HB=P/F.Inpracticalapplication,usuallydirectmeasurementofindentationdiameter,andaccordingtotheloadPandtheballdiameterDfromtheBrinellhardnessvaluetablefoundBrinellhardness(obviously,indentationdiameterislarger,thelowerthehardness,Brinellhardnessvaluerepr
4、esentedbythesmaller)・TherelationshipbetweentensilestrengthandBrinellhardnessofmaterials:ob=K*HB,Kcoefficient,suchaslowcarbonsteelwithK二0.36,K=0.34forhighcarbonsteelandalloysteelforQuenchedandtemperedK二0.325,・・・Waito(2)Rockwellhardness(HR);Withacertainangle(e.g.120DEG)diamondconepre
5、ssureheadoracertaindiameterofDhardenedsteelballundercertainloadundertheactionofPispressedinlothesurfaceofthespecimenremainedafteraperiodoftimetoremovetheload,inthesurfaceofthespecimenwillleaveadeepimpression.ThedepthofthecraterismeasuredautomaticallybyRockwellhardnessmachineanddisp
6、layedbythehardnessvalue・(obviously,thedeeperthedentis,thelowerthehardnessis,thesmallertheRockwellhardnessvalueis).Accordingtodifferentpressureheadandload,Rockwellhardnessisdividedintothreekinds,HRA,HRBandHRC,amongwhichHRCisthemostcommonlyused・ThefollowingconversionbetweenRockwellHR
7、CandHB:HRC二0.1HBBrinellhardness・(1)hardnessofVivtorinox(HV);Adiamondsquareconepresswithaloadof120kgandavertexangleof136degreesispressedintothematerialsurface,andthesurfaceproductoftheindentationdentisdividedbytheloadvalue,whichistheVivtorinoxhardness(HV)HBS,HBWisamoredetailedclassi
8、ficationofBrinellhardness・
