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提出了一种可以实现同种或异种金属材料固态冶金结合的新型激光冲击点焊工艺。实验中,采用Nd∶YAG激光器发出的脉冲激光驱动厚度为30μm的钛箔产生局部塑性变形,并以超高速撞击厚度为100μm的铝板以实现点焊连接。当钛箔的飞行距离分别为0.3、0.6、0.9 mm时,焊点中心的回弹区域面积依次减小,而结合区域面积依次增大。采用冷镶嵌技术制样用来观察焊点的截面特征,发现了沿焊点直径方向振幅和周期变化的波形界面和平直型界面。为研究激光冲击点焊对材料力学性能的影响,应用纳米压痕测试技术测量了垂直于焊接界面方向材料的显微硬度,结果表明焊接界面附近材料的硬度值明显提高。此外,焊接试样的拉伸剪切测试结果表明,当复板和基板发生有效固态冶金结合时其连接强度较高,失效形式通常是焊点边缘破裂。激光冲击点焊为厚度在微米级的异种金属箔板的点焊连结开辟了新途径。
A new type of laser shock spot welding technology that can realize solid-state metallurgical bonding of the same or dissimilar metal materials is proposed. In the experiment, the laser induced by the laser of Nd:YAG laser was used to drive the titanium foil with the thickness of 30μm to generate the local plastic deformation and hit the aluminum plate with the thickness of 100μm at a very high speed to realize the spot-welding connection. When the flying distance of the titanium foil is 0.3, 0.6 and 0.9 mm, respectively, the area of rebound area in the center of the solder joint decreases in turn and the area of the combined area increases in turn. The cold mosaic technique was used to observe the cross-sectional features of the solder joints. The wave-shaped interface and the flat interface were found along the diameter and circumferential direction of the solder joints. In order to study the effect of laser shock spot welding on the mechanical properties of materials, the micro-hardness of the material perpendicular to the welding interface was measured by nano-indentation test. The results show that the hardness of the material near the welding interface is obviously increased. In addition, the tensile shear test results of the welded samples show that the connection strength is high when the effective solid-state metallurgical bonding between the composite substrate and the substrate occurs, and the failure mode is usually the edge of the solder joint is cracked. Laser impact spot welding opens up new avenues for the spot-to-spot bond joining of dissimilar metal foil plates of micrometers in thickness.