Microstructures at the different position of linear friction welded TC11 and TC17 dissimil-lar titanium alloy joint are investigated to understand the mechanism of microstructural formation in the joints using scanning electron microscopy (SEM). The results show that sliding friction and wearing occur on the surface of joint under the conditions of 3mm amplitude of oscillation, 40Hz frequency of oscillation, 66.7MPa friction pressure and 2s welding time. Features of sticking and shearing friction are obtained at the position of 2.5mm distance from the surface of joint. There are porosities existing at the original rubbing interface. Dynamic recrystallization takes place in the region close to TC11 parent material. In contrast, no dynamic recrystallization is observed in the region close to TC17 parent material. There are porosities existing at the position of 5mm distance from the surface of joint. The cracking is observed at the interface of weld zone (WZ) and thermomechanically affected zone (TMAZ) of TC17. At the position of 7.5mm distance from the surface of joint, there no porosities exiting at the original rub-rnbing interface and the cracking is observed at the interface of WZ and TMAZ of TC17. At the position of 10mm distance from the surface of joint, no defects are detected in the joint. At a certain extent, microstructures at the different position of joint reflect the process of microstructural formation in the joints.%为了探明TC11与TC17异质钛合金线性摩擦焊接头连接机理,采用扫描电镜来研究接头不同位置的微观形貌.结果表明,在振幅为3mm、频率为40Hz、摩擦压力为66.7MPa、摩擦时间为2s的条件下,在接头表面表现为“摩擦磨损”特征.在距接头表面2.5mm处,接头具有“粘着剪切”特征,且原始摩擦界面上有微孔存在,TC11钛合金发生了动态再结晶,而TC17未发生动态再结晶.在距接头表面5mm处,界面上有微孔存在,且在TC17焊缝与热机械影响区(TMAZ)交界处产生裂纹.在距接头表面7.5mm处,原始摩擦界面无微孔存在,在TC17焊缝与TMAZ交界处有裂纹存在.在距接头表面10mm处,接头内无缺陷存在.接头内不同位置的形貌在一定程度上反映了接头的形成过程.
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