Plasma beam welding of shape memory alloy

With high-energy plasma beam method, the weldability of the TiNi shape memory alloy sheet was studied.The highenergy plasma beam equipment system was partly designed and founded.The relationship among parameters and its proper adjusting range are acquired.Thus the range of the parameters used in the engineering application was obtained. Some characteristics such as phase, microstructure, shape memory properties and tensile strength of the welded joint were discussed. Results show that the crystal grain in welded joint is large, and new phases such as Ni3Ti and Ti2 Ni separate out.Furthermore, the welding heat-affected zone is narrow, and the welded joint shape restoration rate is 93.8% of the parent metal and the parent metal tensile strength is 1205 MPa.After being kept at 500℃ for 1 hour, the tensile strength of welded joint reaches 750 MPa which is 62.2% of the parent metal and the fracture appears in the center of weld.