Study on the effect of double-sided laser welding of NiTi shape memory alloys wire

NiTi shape memory alloys (SMAs) have important applications in intelligent system design and development due to their flexibility in integration through welding or joining techniques. In this work, both single-sided laser welding and double-sided laser welding processes were used for the welding of NiTi SMAs wire. Then, the macro-morphology, microstructure, phase transformation behavior, mechanical performance, fracture surface characteristics and cyclic tensile properties of the samples obtained under the two welding processes were investigated. The results showed that there were dendrites and equiaxed grains in the fusion zone (FZ) of the double-sided welding samples, without obvious welding defects. Although the phase transformation temperature in the FZ of the samples obtained by the two processes was significantly increased, the temperature rise of the double-sided welded samples was relatively lower. The double-sided welded samples had better tensile strength and elongation, and all samples were ductile fracture. The double-sided welded samples exhibited significant functional fatigue properties improvements compared with the residual strains of the single-sided welded samples in the 1st and 15th cycle tensile tests. This work will improve the performance of NiTi SMAs wire for welding integration applications in smart system design and production.