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采用脉冲激光实现了0.2mm厚TiNi形状记忆合金的对接焊,研究了焊接接头的抗拉强度、断裂形貌、组织和相变过程。结果表明,脉冲激光能够实现薄片状TiNi形状记忆合金的良好对接焊,焊接接头的抗拉强度可达683MPa,为冷轧态母材的97%,断口形貌与母材相似,均为延性断裂。根据晶粒尺寸和显微组织的不同,接头可分为4个区。焊缝中心区为细小的等轴晶,而焊缝边缘为柱状晶组织。对焊接接头进行焊后退火处理后其相变过程与退火态TiNi形状记忆合金的接近。
The butt welding of 0.2mm thick TiNi shape memory alloy was realized by pulsed laser. The tensile strength, fracture morphology, microstructure and phase transition of the welded joint were studied. The results show that the pulsed laser can achieve good butt welding of flaky TiNi shape memory alloy. The tensile strength of the welded joint can reach 683MPa, which is 97% of the cold-rolled base metal. The fracture surface is similar to the base metal, . Depending on the grain size and microstructure, the joints can be divided into 4 zones. The center of the weld is a small equiaxed grain while the edge of the weld is a columnar grain. The phase transition of the welded joint after annealing is similar to that of annealed TiNi shape memory alloy.