激光-MIG复合热源钢/铝异种金属深熔钎焊

Deep-penetration welding-brazing of aluminum/steel dissimilar metal using laser-MIG arc hybrid heat source

采用激光-MIG(Melt Inert-Gas)电弧复合热源实现了4和6 mm厚的钢/铝异种金属对接接头深熔钎焊,并利用扫描电子显微镜观察力接头界面微观组织特征.通过有限元软件分析电弧熔钎焊、激光熔钎焊、激光-MIG复合深熔钎焊三种焊接方法所获接头温度场,同时分析了激光偏转角度对激光-MIG复合深熔钎焊接头温度分布的影响.结果表明,激光-MIG复合深熔钎焊接头温度分布相较于电弧、激光熔钎焊而言较为均匀,接头下部的温度得到明显的提高,可有效增加液态金属在钢表面的润湿铺展程度,有利于获得较为良好的焊缝成形.在激光-MIG复合深熔钎焊过程中,可以通过调整激光偏转角度提高接头界面下部温度,改善界面温度梯度,有利于生成均匀的金属间化合物层.4 mm厚钢/铝激光-MIG复合深熔钎焊焊接接头有着典型的熔钎焊特征,成型质量良好且无明显缺陷生成.界面层化合物为Fe4Al13和Al8Fe2Si,焊缝由α-Al和Al-Si共晶相组成.激光-MIG复合深熔钎焊可实现6 mm对接接头连接,但界面处存在微裂纹.

Deep-penetration welding-brazing process without gap of steel/aluminum dissimilar metal butt joint with a thickness of 4 and 6 mm was achieved using laser-MIG hybrid heat source.The welding parameters were optimized to obtain a sound joint and the microstructure of the interfacial layer was observed by scanning electron microscopy(SEM)and experimental validation.The joint temperature distribution of three welding methods:MIG welding-brazing,laser welding-brazing,and laser-MIG hybrid deep-penetration welding-brazing were investigated by finite element method(FEM)numerical simulation.Moreover,the effect of laser deflection angle on the temperature distribution of the laserMIG deep-penetration welding-brazed joint was investigated.The results indicated that the temperature distribution of laser-MIG hybrid deep-penetration welding-brazed joint was more uniform than MIG welding-brazing and laser welding-brazing.The temperature of the lower part of the joint was increased,which was beneficial to improve wetting and spreading of the liquid metal on the stainless steel and obtain better weld formation.In the laser-MIG hybrid deeppenetration welding-brazing process,the temperature of the lower part of the joint interface and the interface temperature gradient could be improved by adjusting the laser deflection angle,which was beneficial to the formation of uniform intermetallic compound layer.Typical welding-brazing joint characteristic with the thickness of 4 mm using laser-MIG hybrid heat source was found.The main phases of interface layer compounds were composed of Fe 4Al13 and Al8Fe2 Si,and the weld metal consisted of α-Al and Al-Si eutectic.The 6-mm steel/aluminum joint was also achieved by using laser-MIG hybrid heat source,but some cracks at the interface were observed.