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1、料的溶解和元素的擴(kuò)散。當(dāng)液態(tài)釬料過飽和時(shí)，會(huì)在局部形核，形成鎳基固溶體。在島狀鎳基固溶體連成一片時(shí)，溶解停止，母材與鎳基固溶體相發(fā)生固態(tài)擴(kuò)散，在界面處形成很薄的一層磷化物層。隨著溫度的降低，在釬縫中心的液相會(huì)析出Ni（Fe，Cr，Cu）相，由于形狀比較大的Ni（Fe，Cr，Cu）相周圍的液相成分偏離了原始成分，此時(shí)，在Ni（Fe，Cr，Cu）相周圍形成了CrNiP化合物，最后，剩余的液相凝固結(jié)晶，達(dá)到共晶點(diǎn)時(shí)形成Ni3P-Ni（Fe,Cr,Cu）的共晶相。接頭斷裂在釬縫中心處，釬縫中心含有脆性的Ni3P相，斷裂形式為準(zhǔn)解
2、理斷裂。裂紋在脆性相Ni3P處萌生并擴(kuò)展，在遇到鎳基固溶體時(shí)停止擴(kuò)展，經(jīng)過一段時(shí)間之后，在剪切應(yīng)力的作用下裂紋會(huì)在鎳基固溶體周圍再次形成并繼續(xù)沿著脆性相擴(kuò)展。關(guān)鍵詞：316L不銹鋼，合金元素Cu，微觀組織，抗剪強(qiáng)度，釬焊機(jī)理II萬方數(shù)據(jù)STUDYONTHEPROCESSANDMECHANISMOFBRAZINGSTAINLESSSTEELUSINGMODIFIEDNICKEL-BASEDBRAZINGALLOYABSTRACTWiththequalityoflifeofpeopleimprove,demandforcar
3、sisalsomoreandmorehigh,however,effectsofautomobileexhaustpollutionofourenvironment,especiallypresentsasignificantchallengetolargeandmedium-sizedcitylivingenvironment.EGRcoolercanimprovetheenvironment,reducingemissionsofpollutants.Manufacturingcoolerpartsofthemate
4、rialusuallychoose304、306、316and316Lstainlesssteelprecisioncastingsorprofile,the316Lstainlesssteelwithgoodresistancetointergranularcorrosionandbecomethepreferredmaterial.Intheweldingprocessofstainlesssteel,stainlesssteelwithnickelbasebrazingfillerismostcommon,howe
5、ver,duringbrazingalloying,brazingseamcentergeneratesbrittleintermetalliccompoundphase,whichmakesthemechanicalpropertiesoftheweldedjointisreduced,therefore,needtostudytheinteractionbetweenbasemetalandfillermetalandhowtoreducethebrittlecompoundbrazingseamcenter.Bas
6、edontheBNi-7brazingalloy,addingalloyingelementsCu,throughthebrazingalloyformulamorereasonabledesigntooptimizetheweldingjoint.Theresearchresultsshowthat:themeltingpointofthebrazingalloyalloyelementsaddeddecreasedafterCu,butthesolid-liquidphaselinetemperatureslight
7、lyincreased.Improvedwettingfrontaretheprecursorfilmexists,theprecursorfilmplaysanimportantroleinbrazingalloywettabilitycontactangledecreaseandincrease.WiththeincreaseofCucontent,thebrazingtemperatureandholdingtime,theprecursorfilmbrazingalloywettingfrontwidens,br
8、azingalloyspreadingareaincreases,thewettabilityimprovement.TheadditionofCuorganizationisNi(Cr,Cu)solidsolution,Ni3P-Ni(Cr,Cu)eutecticstructureandasmallamountof
