TiNi形状记忆合金薄片的微激光焊接工艺研究

Study on Micro-laser Welding Process of TiNi Shape Memory Alloy Sheet

采用微激光对厚度为0.2mm的TiNi形状记忆合金薄片进行焊接,通过正交试验以获得最大的接头抗拉力为目标对工艺参数进行了优化,并分析了工艺参数对焊接接头表面及横截面形貌的影响。结果表明,焊接接头获得最大抗拉力的最优工艺参数是:脉冲功率百分比21%、脉冲宽度2.3ms、脉冲频率4Hz,此时焊接接头的承载能力达到母材的97%。当微激光焊的功率百分比、脉冲频率、脉冲宽度过大时会产生热量的积累、导致焊缝发生烧穿;过小时激光脉冲的熔透能力较弱、导致焊缝未焊透,这两者是导致焊接接头承载能力较差的主要原因。

0.2 mm thick TiNi shape memory alloy sheet was butt-welded using micro impulse laser. The processing parameters were optimized by orthogonal experimental getting the largest stretching resistance. Influence of processing parameter on the surface and cross-section morphology of welded joint was studied. The results show that the optimized processing parameters that can get the maximum stretching resistance are pulse power percentage 21, pulse frequency 4 Hz and pulse width 2.3 ms. With the optimized processing parameters, the stretching resistance of the welded joint can achieve 97% of base metal. Bum through in welded seam is easy to occur when pulse power percentage, pulse frequency or pulse width are too big and nonpenetration occurs when these parameters are too small. Both bum through and nonpenetration are the main reason lead to the decrease of stretching resistance.