时效对TiNi合金激光焊缝金属逆相变温度的影响  

Effect of aging treatment on reverse phase transformation temperature of TiNi alloy laser welded metal

作　　者：杨成功[1] 单际国[1,2] 任家烈[1] 

机构地区：[1]清华大学机械工程系,北京100084 [2]清华大学先进成形制造教育部重点实验室,北京100084

出　　处：《材料科学与工艺》2014年第1期19-23,共5页Materials Science and Technology

摘　　要：为探索焊缝金属逆相变温度随时效处理工艺的变化规律,利用OM、SEM、DSC对母材和经过时效处理的激光焊缝金属的组织形貌、析出相分布及逆相变温度进行了研究.结果表明,焊缝金属逆相变开始温度As和结束温度Af对焊接工艺参数不敏感,但时效处理能够明显提高焊缝金属的逆相变温度,其中As升高的更快,且焊缝金属As、Af与时效时间呈近线性关系.时效处理能明显提高焊缝金属的As、Af,其机理是时效促进了沉淀相析出,沉淀相对基体相的钉扎作用增加了低温马氏体的稳定性;另外,富Ni沉淀相的析出导致基体相Ni含量降低,也促进了As、Af升高.The reverse phase transformation temperature of TiNi laser welded joint is mainly determined by weld metal. It is of great significance to explore how the reverse phase transformation temperature （RPTE） of weld metal is influenced by aging treatment process, and to control RPTT of the total welded joint. By means of OM, DSC and SEM, the microstructure, the RPTT and the distribution of precipitated phase were investigated for both the base metal and the weld metal with different aging treatment. The result showed that the RPTT of weld metal is not sensitive to the welding parameters, but can be increased apparently by aging treatment. The start temperature （As） goes up more rapidly than the finish temperature （Af） after aging treatment. Both the change of As and Af yielded a linear relationship to the aging time. The increased As and Af after aging can be explained by the precipitation of Ni-rich phase, which owns pinning effect on the matrix and makes the martensite more stable. Moreover, the precipitation causes the reduction of the Ni element in the matrix, which is also helpful to the increase of As and Af.

关 键 词：TINI形状记忆合金 激光焊缝 马氏体逆相变温度 时效处理 

分 类 号：TG456.7[金属学及工艺—焊接]