(1. 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；
2. 航天科工 哈尔滨风华有限公司，哈尔滨 150036)
摘 要: 对TC21钛合金进行电子束焊接试验，通过光学显微镜和透射电子显微镜(TEM)对焊缝内不同特征区域的精细显微组织进行分析，并对各个区域的显微硬度进行测量。结果表明：TC21钛合金在焊接过程中，焊缝区和热影响区Ⅰ、Ⅱ区内发生了马氏体转变，由针状马氏体α′相和残余β相组成。热影响Ⅲ区只发生了α相向β相的转变。马氏体转变量与接头不同区域的降温速率有关，焊缝区内马氏体数量最大，尺寸最大，马氏体强化效果最明显，显微硬度最高。而在热影响Ⅲ区内无马氏体强化效果，且β相数量增多，硬度低于母材的，发生软化。
关键字: TC21钛合金；精细组织；马氏体转变；显微硬度
electron beam welding joint of TC21 Ti alloy
（1. State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology,
Harbin 150001, China;
2. Harbin Fenghua Limited Corporation, China Aerospace Science and Industry Corporation, Harbin 150036, China）
Abstract:The electron beam welding of TC21 titanium alloy was carried out. The fine microstructure in various feature regions of weld was analyzed by optical microscopy and transmission electron microscopy. As well, the microhardness of each region was measured. The results show that martensitic transformation occurs in weld zone and heat affected zone I and II which are characterized by acicular martensite α′ phase and retained β phase. The transformation of α to β phase is the only phase change process in heat affected zone Ⅲ. The extent of martensitic transformation is relevant to cooling rate in various region of the joint. The microhardness in weld zone is the highest for martensitic strengthening because there is the largest number of martensite with the biggest size in it. But the material in heat affected zone Ⅲ softened during welding with the increase of β phase and lack of martensitic strengthening effect.
Key words: TC21 Ti alloy; fine microstructure; martensitic transformation; microhardness
