Microstructure and properties of laser micro welded joint of TiNi shape memory alloy  

TiNi形状记忆合金片激光微焊接接头的组织性能(英文)

作　　者：龚伟怀[1] 陈玉华[1,2] 柯黎明[1] 

机构地区：[1]南昌航空大学轻合金加工科学与技术国防重点学科实验室,南昌330063 [2]哈尔滨工业大学现代焊接生产技术国家重点实验室,哈尔滨150001

出　　处：《Transactions of Nonferrous Metals Society of China》2011年第9期2044-2048,共5页中国有色金属学报（英文版）

基　　金：Project(200804)supported by State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,China

摘　　要：Butt welding of 0.2 mm-thick TiNi shape memory alloy sheet （SMA） was carried out using impulse laser, and tensile strength, fracture morphology, microstructure and phase change behaviour of welded joint were studied. The results show that using impulse laser can realize good butt welding of TiNi SMA sheet, tensile strength of welded joint is 683 MPa, which achieves 97% of that of cold rolled base metal, and the fracture mode of welded joint is ductile type as well as base metal. The welded joint can be divided into four zones according to grain size and microstructure. The microstructures of welded seam center zone are fine equiaxed crystals and the microstructures of both lower surface and upper surface edge zones are columnar crystals. When welded joint is vacuum annealed after welding, the phase transformation process is basically similar to the annealed base metal.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。

关 键 词：TiNi shape memory alloy laser micro welding microstructure properties phase transformation behavior 

分 类 号：TG139.6[一般工业技术—材料科学与工程] TG407[金属学及工艺—合金]