薄板不锈钢与铝合金激光点焊工艺及裂纹形成机理研究  

Research on Welding Technology and Crack Formation Mechanism of Pulse Laser Spot Welding between Thin Plate Stainless Steel and Aluminum Alloy

作　　者：刘毅[1] 余圣甫[1] 王丹丹[1] 

机构地区：[1]华中科技大学材料成形与模具技术国家重点实验室,湖北武汉430074

出　　处：《应用激光》2016年第1期46-52,共7页Applied Laser

摘　　要：采用Nd:YAG激光脉冲对不锈钢薄板与铝合金板材进行点焊搭接试验,研究了电流、脉宽对焊点熔深、焊点裂纹的影响,测试并分析了焊点的结合强度。研究结果表明,焊点的熔深随着电流、脉宽的增大而增加,且与电流、脉宽的乘积呈正相关关系;焊点裂纹分表面宏观裂纹与内部显微裂纹,表面宏观裂纹是由于Si的偏析及其低熔共晶,在焊点熔池凝固收缩时产生了热裂纹。内部显微裂纹是由于焊点的铝合金熔合区形成了铝铁金属间化合物所导致的脆性相裂纹。通过参数优化,电流为120A、脉宽为7ms、离焦量为-3mm时,既能避免焊点宏观裂纹,又能获得一定熔深;熔合区域的金属间化合物厚度可控制在5μm左右,内部显微裂纹倾向较小,3个焊点拉伸剪切力可达75.2N。In this paper,stainless steel sheet and aluminum sheet were lap joined using Nd：YAG pulse laser.The effects of current and pulse duration on weld penetration and weld crack were studied,and shear-tensile strength of welding spots were tested and analyzed.It was concluded that：weld penetration increases with current and pulse duration and has a positive correlation with the product of current and pulse duration;Cracks in the weld include surface macro crack and inner micro crack.Segregation of silicon and low-melt-point silicate caused hot crack tendency in macro welding spot,while brittle Fe-Al phases caused micro crack in the fusion line of aluminum;An optimization of process parameters showed that when the current is 120 A,pulse duration is 7ms and the defocusing distance is-3mm,an acceptable penetration can be obtained while the macro crack is avoided.Meanwhile,the thickness of intermetallic compounds could be controlled under 5μm,which would result in a less interior microscopic crack tendency.As a result,the shear-tensile strength of all three welding spots can reach 75.2N.

关 键 词：激光技术 铝钢焊接 热裂纹 金属间化合物 

分 类 号：TG113.26[金属学及工艺—物理冶金]