连续-脉冲双激光束焊接钢-铝合金

CW/PW Dual-Beam YAG Laser Welding of Steel/Aluminum Alloy Sheets

随着汽车轻量化越来越得到重视,钢-铝合金异种金属焊接结构成为研究的重点。采用YAG连续(CW)和脉冲(PW)两种激光设备,对连续-脉冲双激光束复合热源焊接工艺进行了研究,并借助扫描电镜(SEM)、电子探针微区分析(EPMA)、显微硬度计、拉伸实验机等设备对焊缝进行了分析与测试。实验结果表明,连续激光匹配适当的脉冲激光进行双激光焊接,可以有效地减少或避免气孔的产生,同时可以使用低功率的连续激光实现较深的焊接,扩大低功率激光设备使用范围。双激光束焊接过程中,由于脉冲激光的作用,焊缝中的Fe穿入Al中,在焊缝底部Fe-Al交界处形成了钩状的不规则结构,这种结构的产生可以增强Fe,Al两种材料的连接强度。在焊缝底部Fe-Al交界处形成了高硬度、高脆性的Fe-Al金属间化合物。钢-铝合金双激光搭接焊焊缝剪切强度为128 MPa,剪切断裂断口呈现为准解理型断裂形貌。

The development of a new welding method for dissimilar metals is strongly required for weight reduction of automobiles.The most popular and important combination of dissimilar metals is steel and aluminum.The lap joining of steel/aluminum alloy is carried out using the continuous wave-pulse wave（CW-PW） dual-beam YAG laser welding method.The tests are also performed for the lap joints using scanning electron microscopy（SEM）,electron probe microzone analysis（EPMA）,micro-hardness tester,tensile testing machine.The results show that the CW laser matching the appropriate PW laser for dual-beam laser welding can effectively reduce or avoid the produce of pores,as well as the deeper penetration can be obtained using the low-power CW laser,which expands the scope of the low-power CW laser equipments.In the dual-laser beam welding process,the Fe penetrates into the Al due to the role of pulsed laser.And the irregular hook-like structure produced in the bottom of welding seam,which can enhance the Fe/Al joint strength.A brittle Fe-Al intermetallic compound（IMC） layer formed at the join interface.The shearing strength of the lap joint is 128 MPa,and the morphology is quasi-cleavage fracture.