近等原子比钛镍合金氩弧焊接接头的组织和性能

Microstructure and Performance of Argon Arc Welding Joint of Nearly Equatomic TiNi Alloy

借助金相显微镜、拉伸实验和弯曲回复法等手段研究了近等原子比钛镍形状记忆合金氩弧焊接接头的组织和性能。研究结果表明，近等原子比钛镍形状记忆合金氩弧焊接接头的显微组织可分为三个区，分别是粗大柱状晶区、细小柱状晶区和热影响区。由于焊接接头显微组织与母材之间的差别，在相同的应变下，近等原子比钛镍形状记忆合金氩弧焊接接头的回复温度明显高于母材，记忆性能变差。焊接后的近等原子比钛镍形状记忆合金的屈服强度与母材相近，但抗拉强度和延伸率远低于母材。氩弧焊接近等原子比钛镍合金的显微组织在热处理后不会发生明显变化，经过形变后，焊接接头的回复温度与母材仍有差别，显微组织的不同是造成这一现象的原因之一。

The microstructurc and performance of argon arc welding joint of nearly equatomic TiNi alloy were studied by employing metallographic microscope, tensile testing experiment and bend and [ree recovery method. Research results indica- ted that the mierostructure of the welding joint could be divided into three zones, which are coarse columnar grains zone, fine columnar grains zone and heat affected zone, respectively. Under the same bending strain, the recovery temperatures of the welding joint and base metal are different because of the differences existing in the microstructure, and the recovery tempera- ture of the welding joint is higher than that of the base metal, which indicating the shape memory performance become worse. The yield strength of the welding ioint is close to that of the base metal. However, the tensile strength and elongation of the welding joint are far below that of the base metal. The microstructure of the welding joint will not be obviously changed after different heat treatment. The differences of the recovery temperature of the welding joint and base metal are still in existence after thermo--mechanical treatment, and the difference between the microstructure of welding joint and base metal may be one of the reasons which caused the difference in recovery temperature.