Microstructural evolution and numerical simulation of laser-welded Ti_(2)AlNb joints under different heat inputs  

作　　者：Ke-Zhao Zhang Zheng-Long Lei Yan-Bin Chen Ke Yang Ye-Feng Bao 

机构地区：[1]College of Mechanical and Electrical Engineering,Hohai University,Changzhou,213022,China [2]State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology,Harbin,150001,China

出　　处：《Rare Metals》2021年第8期2143-2153,共11页稀有金属（英文版）

基　　金：financially supported by the National Natural Science Foundation of China(Nos.51804097 and 51879089);State Key Laboratory of Advanced Welding and Joining,Harbin Institute of Technology(No.AWJ-19M16);the Fundamental Research Funds for the Central Universities of China(Nos.2018B05214 and B200202219);Changzhou Sci&Tech Program(No.CJ20190049)。

摘　　要：The influence of heat input on the microstructural evolution of laser-welded Ti_(2)AlNb joints was investigated in this study.The thermal cycles during welding process were analyzed by numerical simulation.In the heat affected zone(HAZ),the amount ofα_(2)and O phases decreased with laser power increasing.During the heating period,α_(2)→B2and O→B2transformations occurred,but the decomposition of the B2phase intoα_(2)and O phases was suppressed during the cooling period.The heat transfer in the HAZ generated more equiaxed B2grains,fewer LAGBs and a weaker{001}<110>texture due to recovery,recrystallization and grain growth.The phase composition of the fusion zone remained single with only the B2phase with the increase in heat input,but the mode of grain growth transformed from cellular growth into cellular dendritic growth.A finite element model was established to simulate the thermal cycles during the welding process.Higher heat input induced higher peak temperature,leading to higher temperatures in the HAZ for longer periods of time,which was beneficial for theα_(2)→B2and O→B2transformations.The calculated cooling rates in both the HAZ and in the fusion zone were faster than the critical cooling rate for B2→α_(2)and B2→O transformations.

关 键 词：Ti_(2)AlNb-based alloys Laser welding Heat input Microstructural evolution 

分 类 号：V252.2[一般工业技术—材料科学与工程] TG456.7[航空宇航科学与技术—航空宇航制造工程]