7A05铝合金CO_2激光-MIG复合焊气孔形成及控制机理  

Porosity formation and prevention mechanism in 7A05 aluminum alloy welded by CO_2 laser-MIG hybrid welding

作　　者：刘红伟[1,2] 李京龙[1] 马志华[2] 冯胜强[2] 马良超 

机构地区：[1]西北工业大学,陕西西安710072 [2]中国兵器科学研究院宁波分院,浙江宁波315103

出　　处：《焊接技术》2016年第5期79-82,8,共4页Welding Technology

基　　金：宁波市创新团队项目(2014B81004)

摘　　要：采用CO_2激光-MIG复合焊对7A05铝合金进行了焊接工艺研究,研究了热源间距、焊接速度及MIG焊接电流对焊接气孔形成规律的影响。通过对焊缝进行X射线检测,进一步探讨了气孔的特征及其形成原因和控制方法。结果表明,焊缝中的气孔数量与板材的焊前处理状态、焊接保护效果及焊接工艺有着显著的联系。其中,冶金类气孔的形成机制是铝合金板材及焊接材料表面的水分分解出氢溶入到熔池中不能逸出,因而,通过加强焊前处理及减少熔池吸氢时间可有效控制冶金类气孔的形成;工艺类气孔的主要形成机制是激光深熔焊的"匙孔"坍塌,而通过优化激光-MIG复合焊接工艺及加强熔池背部保护也可较好地控制工艺类气孔的形成。7A05 aluminum alloy joints were fabricated by CO_2 laser-MIG hybrid welding at different parameters.Influences of laser-MIG distance, welding speed and MIG welding current on porosity were investigated in detail. Xray inspection was used to analyze the characteristics and formation mechanism of porosity in the welded joint. The experimental results indicated that the number of porosity was evidently affected by the plate processing state before welding, welding protection and welding process. The formation mechanism of metallurgical type of porosity was that the hydrogen blended into the molten pool and could not overflow as water on the surface of the plate and welding materials split into hydrogen and oxygen at high temperature. Thus, metallurgical type of porosity could be reduced by strengthening treatment before welding and reducing molten pool hydrogen absorption time. In addition, the formation of technology type of porosity was mainly due to the 'keyhole' collapsing of laser deep penetration welding.Optimizing the laser-MIG hybrid welding process and adjusting protection measures of the back of molten pool could suppress technology type of porosity.

关 键 词：7A05铝合金 CO2激光-MIG复合焊 气孔 

分 类 号：TG456.9[金属学及工艺—焊接] TG457.14