简介:<正>据国家经贸委预测,2002年国际有色金属市场有以下特点:首先,联合重组加快,产业集中度提高。为了适应市场竞争,国外大企业近年来普遍加快了收购、兼并、联合步伐、组建更大规模的跨国公司(多数为采选冶加工联合企业),实现规模化运营,扩大市场份额。例如,美国铝业公司(Alcoa)是一家集铝土矿开采、氧化铝、电解铝生产和铝材加工为一体的综合性铝业集团,1998年兼并了美国阿鲁玛克斯(ALUMAX)公司,收购了世界第三大制铝公司美国雷诺兹金属公司(Reynolds),当年销售额达210亿美元,年生产铝352万吨,占世界铝产量的15%。
简介:Themechanicalproperties,creepdamage,creeprupturestrengthandfeaturesofinterfacialfailuresofweldedjointsbetweenmartensite(SA213T91)andpearlitesteel(12Cr1MoV)havebeeninvestigatedbymeansofargontungstenpulsedarcwelding,hightemperatureacceleratedsimulation,creeprupture,mechanicalpropertytestsandscanningelectronicmicroscope(SEM).Theresearchresultsindicatethatthemechanicalpropertiesofovermatchedandmediummatchedjointdeteriorateobviously,andtheyaresusceptibletocreepdamageandfailureafteracceleratedsimulationoperation500h,intheconditionofpreheat250℃,andpostweldingheattreatment750℃×1h.However,themechanicalpropertiesofundermatchedjointarethebest,theinterfacialfailuretendencyofundermatchedweldedjointislessthanthoseofmediumandovermatchedweldedjoint.Therefore,itisreasonablethatlowalloymaterialTR31isusedasthefillermetalofweldbetweenSA213T91and12Cr1MoVsteel.
简介:ThediffusionbondingofAZ3\BMgalloyandQ235steelwasinvestigatedwithaZn-5AIalloyasinterlayerandunderdifferentholdingtimerangingfrom3to1200s.Themicrostructureandphasecompositionsofbondedjointswerecharacterizedbyscanningelectronmicroscopy(SEM),energydispersivespectrometer(EDS)andX-raydiffraction(XRD)methods.TheshearstrengthofMgalloy/steeljointswasmeasuredbytensiletester.Itwasfoundthatthemicrostructureofbondedjointsevolveddramaticallyalongwiththeprolongationofholdingtime.Undertheholdingtimeof3s,themainpartofjointwascomposedofMgZn2phaseanddispersedAl-richsolidsolutionparticles.Whenincreasedtheholdingtimemorethan60s,theexcessivesolutionofAZ3\Bintotheinterfacialreactionarealedtotheformationofcoarsephaseandeutecticmicrostructure,andalsothecomplexFe-AlandMg-Al-ZnIMCsattransitionlayerclosedtoQ235steelside.Accordingtothetensiletestingcharacterizations,thejointsobtainedunderholdingtimeof3sexhibitedthebestshearstrengthof84MPa,andthefractureoccurredattheintermediarypartofjointwheretheflexibleAl-richsolidsolutionparticlescouldhelptoimpedethemicrocrackpropagations.Withprolongingtheholdingtimeto600s,theshearstrengthofjointswasdeterioratedenormouslyandthefracturepositionwasshiftedtothetransitionlayerpartclosedtoQ235steel.
简介:ButtjointsofQCrO.8/1Cr2lNiSTiequal-thicknessdissimilarmaterialswereobtainedbyelectronbeamweldingwithfixedacceleratingvoltage60kVandfocuscurrent1.99A,changedelectronbeamcurrentandweldingvelocity.MicrostructureandcompositionoftheEBWjointwereinvestigatedbymeansofopticalmicrographyandEDXanalysis,mechanicalpropertiesofthejointwerealsotested.Theresultsshowthatjoint'smacrostructurewasdividedintothreezones:topweldzonenearQCrO.8andbottomweldzoneconsistingofCu(ss.Fe)withacertainamountofdispersedlydistributed(α+ε)mixedmicrostructure,middleweldzoneconsistingof(α+ε)microstracturewithasmallamountofCu(ss.Fe)particles.MorphologicalinhomogeneousmacrostructureandunevenchemicalcompostionofQCrO.8/1Cr21NiSTijointbyEBWarethemostimportantfactortoresultindecreasingjoiningstrength.
简介:本文针对N4/1Cr18Ni9Ti与N4/0Cr25Ni20复合板的特殊焊接要求,根据NB/T47014—2011《承压设备焊接工艺评定》的要求,制备2块N4/1Cr18Ni9Ti试板,2块N4I/0Cr25Ni20试板,尺寸均为500mmX150mmX(4+14)mm。不锈钢基层采用GTAW打底,焊丝选用HOCr21Ni10,SMAW填充与盖面,焊条选用A302与A402。镍复层的焊接采用手工钨极氩弧焊,焊丝选用含Ti、AI等脱氧元素的ERNi-1焊丝,保护气体选择98%Ar+2%H2。试板焊接完成,外观检验合格后进行100%RT,检测结果符合JB厂r4730,2—2005I级合格,镍复层进行100%PT,检测结果符合JB/T4730.5—2005I级。两种焊接试板分别取样并做拉伸、弯曲力学性能分析,镍复层焊缝做化学成分分析。通过两块焊接试板试验对比,不锈钢基层焊接材料选择HOCr21Ni10焊丝与A302焊条。镍复层焊接采用ERNi-1焊丝,焊接保护气体为98%Ar+2%H2。通过焊接工艺评定试验研究,解决了N4/1Cr18Ni9Ti与N4I/0Cr25Ni20复合板焊接问题,提高了用户坩埚的返修质量与再次使用寿命,为使用单位节约了成本。