坡口间的焊接残余应力

坡口间的焊接残余应力坡口间距对应的影响也较为明显，从表中可以看出，坡口间距越大，应力值也有明显的增大，最大间隙处应力值（为最小间隙处应力值的3.5倍左右）。从理论上分析，坡口越大，需填充的金属越多，焊接时热作用时间越长，温度也越高，因而产生更大的应力。Correspondingarerelativelyobvious,theinfluenceofgroovespacingcanbeseenfromthetable,thegroovespacing,thegreaterthestressvaluehadincreasedobviously,thebiggestgapinstressvalue(forminimumclearancestressvalueofabout3.5times).Theoreticallyanalysis,groove,thegreatertheneedtofillthemoremetal,weldingthermaleffectwhenthelongerthetime,thehigherthetemperature,andthushaveagreaterstress.4.3坡口间距对机械性能的影响4.3groovespacingeffectonthemechanicalproperties://可以看出，坡口间距对机械性能的影响较小，但坡口间距对缺陷有较大的影响。两个试样都做了宏观金相检查，坡口间距越小，未焊透缺陷倾向增加。所以，坡口间距间接地影响了焊接接头的强度，降低疲劳强度。Itcanbeseenthatgroovespacinghavelesseffectonthemechanicalproperties,butthegroovespacinghasalargereffectondefects.Twosampleshavemacrometallographicexamination,groovespacingissmaller,lackofpenetrationdefectstendtorise.So,groovespacingindirectlyaffectthestrengthofweldingjoint,reducefatiguestrength.5金相分析5metallographicanalysis在相应的最大坡口端和最小坡口端，分别取试样进行金相分析，对比母材金相，组织变化差异很小。可见，因所用材料为普通碳素结构钢（管板和筒体材料都选用了Q235-B），土工格栅厂家这类材料的组织在加热时，长大倾向并不明显。可以认为，坡口间距对焊接接头及热影响区金属组织的影响是不大的。或者说，因焊接接头及热影响区金属组织所引起的焊接接头失效现象的因素要比焊接缺陷和应力变化所产生的影响小得多。Inthecorrespondingthemostslopesendandminimumgrooveendmouth,samplesweretakenformetallographicanalysis,contrastmaterialmetallographic,smalldifferencesinorganizationalchange.Visible,becausethematerialsusedforordinarycarbonstructuralsteel(tubeplateandthecylindertheQ235materialselectionare-B),theorganizationofthiskindofmaterialwhenheated,grewuptendencyisnotobvious.Canthink,groovespacingontheinfluenceoftheweldandheataffectedzonemetalgroupisnotbig.Or,becauseoftheweldandheataffectedzonemetalorganizationcausedbytheweldingjointfailurefactorsthanweldingdefectsandtheimpactofstresschangeslittle.6结论://通过以上分析，造成管板与壳体连接焊接接头失效的重要因素中，坡口尺寸大小是其中之一。因为坡口尺寸大小对焊接接头内部缺陷的产生及热影响区的焊接残余应力大小有着重大的影响，坡口越大，焊接缺陷产生的可能性增加，焊接残余应力增加。在焊接实践中，可以通过选择合适的坡口尺寸，酿酒设备配以合理的焊接工艺参数，尽可能降低焊接接头及热影响区的焊接残余应力，则可以减少此类失效现象的发生，从而减小生产中的经济损失。Throughtheaboveanalysis,resultinginthetubesheetandshellconnectionweldfailureofimportantfactors,thegroovesizeisoneofthem.Becausethegroovesizeofinternaldefectsofweldingjointandtheweldingresidualstressofheataffectedzonesizehasasignificantimpact,thegroove,thegreaterthepossibilityofweldingdefects,weldingresidualstressisadded.Inweldingpractice,canchoosetherightgroovesize,withreasonableweldingprocessparameters,asfaraspossiblereducetheweldingresidualstressofweldandheataffectedzone,andcanreducethefailurephenomenon,soastoreducetheeconomiclossesinproduction.