| Ni-Ti shape memory alloy is a new type of metal functional material developed in recent years. The structure and shape memory function in the thermal-effected zone is often changed by traditional high-temperature molten welding. Therefore, it is very important and emergent to research the welding technology of Ni-Ti alloy that the structure and shape memory function are unchanged. With different mechanics from molten welding, the metallurgical bonding between metals can be achieved by exploding welding at the precondition of the structure and property of metal unchanged. This study is supported by Beijing Haoyu Industry and Trade Co Ltd Explosion Processing Mill.The experimental research on welding Ni-Ti shape memory alloy was done by exploding welding in this paper. Ni-Ti alloy belongs to low impact-toughness material, how to solve the problem of brittle failure in exploding at normal temperature is a key to realize the exploding welding.Aiming at the problem of Ni-Ti alloy brittle failure in exploding at normal temperature, the main researches were done as follows:1.By the test of mechanical properties and observation of phase structures of Ni-Ti alloy, the reason of brittle failure was analyzed.2.The reasonable exploding welding technology was arranged and optimal exploding experimental parameters were determined.3.The exploding welding experiment of Ni-Ti shape memory alloy was done.4.The exploding welding experiments of Ni-Ti alloy/brass and Ni-Ti alloy/stainless steel plate were done.5.By the optical microscope and TEM and FM-700 semiautomatic digital micro- sclerometer, the microstructure and properties of Ni-Ti alloy in the bond interface were tested and studied. Additionally, the phase structures of Ni-Ti/brass and Ni-Ti/stainless steel plate in the bond interface were analyzed. The results show that, through the reasonable arrangement of exploding welding technology and determination of exploding experimental parameters, the brittle failure problem of Ni-Ti alloy by exploding welding at normal temperature was solved and the exploding welding of Ni-Ti alloy/Ni-Ti alloy, Ni-Ti/brass and Ni-Ti/stainless steel were realized successfully. The analysis results of periodic waveshape in the bond interface and the structures and properties in the melting layer and diffusion layer show that, at the precondition of the structures and properties of flyer plate and base plate changed little in the bond interface, the metallurgical bonding of exploding welding was achieved. This research provides a new practical way for the welding of Ni-Ti shape memory alloy. |
