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1、2009年第6期轻金属59·轻合金及其加工·镁合金富Ar混合气体TIG焊电弧行为①及其对焊缝质量的影响②张冠宇,惰方飞,苗晋琦,刘胜新,关绍康,胡中华,秦亚伟,牛济泰(郑州大学材料科学与工程学院,河南郑州450002)摘要:采用富Ar混合气体TIG焊焊接了镁合金板材,分析了Ar、He、CO2和N2不同配比混合气体的电弧特性及其对焊缝成形、熔深、显微硬度和抗拉强度的影响。结果表明:富Ar混合气体加入一定比例CO2会造成镁元素蒸发,焊接过程中有飞溅现象,加入一定比例N2会在焊缝表面生成Mg3N2膜,影响焊缝质量。He-Ar混合气体随着氦气体积分数的增大,电弧稳定性增强
2、,阴极热功率所占电弧总功率的比例减少。当He体积比等于50%时,电弧阴极区域明显收缩而阳极区域发散扩展,可获得外形美观、熔透率高、焊缝区组织均匀细小的镁合金焊接接头。焊缝的平均显微硬度为60HV,达到母材的82.6%,抗拉强度为186MPa,是母材的76%,断裂发生在热影响区,属于韧-脆混合断裂。关键词:镁合金;富Ar混合气体;He-ArTIG;电弧;焊缝质量中图分类号:TG146.2文献标识码:A文章编号:100221752(2009)0625925StudyonarcbehaviorofmixedgasofwealthyargonTIGweldingandit
3、seffectsonweldingqualityofmagnesiumalloyZHANGGuan-yu,SUIFang-fei,MIAOJin-qi,LIUSheng-xin,GUANShao-kang,HUZhong-hua,QINYa-weiandNIUJi-tai(SchoolofMaterialsScienceandEngineering,ZhengzhouUniversity,Zhengzhou450002,China)Abstract:ThemagnesiumalloyplateswereweldedbymixedgasofwealthyargonT
4、IGwelding.ThearcphysicalcharacteristicanditsinfluenceontheweldingqualitywereanalysedundervariousvolumeratiogasmixturesofAr,He,CO2andN2.TheresultsindicatethatmixedgasofwealthyargonbyaddingcertainpercentageofCO2courseevaporationofmagnesiumelementandspattering,thequalityofweldingisaffect
5、edbythemembraneMg3N2gengeratedinthesurfaceofweldmentbyaddingcertainpercentageofN2.ThearcstabilityimproveswiththeHevolumeratioincreasing,whiletheproportionofcathodehotpowertothetotalarccapacitydecrease.Thecathodezoneofelectricarcshrinksevidentlyandtheanodiczoneexpandswhenthevolumeratio
6、ofHegasislessthan50%,inaddition,thegoodappearanceweldofmagnesiumalloywithhighpenetrationandhomogeneousfinee2quiaxialgrainwasobtained.Theaveragemicrohardnessofweldmentreach60HVwhichis82.6%ofthebaseplate,thetensilestrengthofweldmentreach186MPawhichis76%ofthebaseplateandthefractureoccurr
7、edintheheat-affectedzone,belongingtotough-brittlemixedmorphology.Keywords:magnesiumalloy,mixedgasofwealthyargon,He-ArTIG,arc,weldquality镁合金被誉为21世纪最富有开发和应用潜力〔1〕1试验方法的“绿色工程材料”,是当前材料研究的热点。由于镁合金熔点低、导热率和线膨胀系数高、表面张力试验材料为4mm厚的商用AZ31镁合金板材,小,其焊接方法和工艺要求非常严格,镁合金的焊接将其加工成150mm×25mm×4mm的试件,用砂纸技术已成为
8、目前解决其
