激光成形TC17钛合金线性摩擦焊接头组织与力学性能

Microstructure and mechanical properties of linear friction welding joint of TC17 titanium alloy fabricated by laser forming

立足航空发动机整体叶盘叶片发生损伤后采用线性摩擦焊进行修复的背景需求,针对航空发动机常用的TC17钛合金,开展激光成形制备一侧焊接台后再线性摩擦焊的典型接头组织分析、力学性能测试以及断口分析,重点分析了接头中激光沉积区组织在线性摩擦焊前后演变特征及与力学性能影响关系,结果表明,缩短量的大小决定了接头中含有的激光成形区组织多少,参与焊接过程的激光成形沉积区组织发生了明显的再结晶,原始的粗大晶粒破碎,晶粒内部析出细小α相,三种典型接头的拉伸性能均与母材相当,当焊缝中挤出去除沉积区组织时,接头高周疲劳强度可达到母材的90%以上.

Under the background of repairing damaged blades of blisks with linear friction welding,aimed at TC17 titanium alloy which is commonly used for aero-engine blades,one of the welding stub is fabricated by laser forming,microstructure analysis,mechanical properties test and fracture analysis of typical welded joints were carried out,the evolution characteristics of the laser deposition zone before and after linear friction welding and its influence on mechanical properties were emphatically analyzed.Results showed that the size of shortening determines the amount of laser forming structures in the joint,obvious recrystallization occurs in the laser forming deposition zone which participated in the welding process,the original coarse grains were broken and small α phases were precipitated inside the grains.the tensile properties of the three typical joints are equal to that of the base metal,when the structure of deposition zone is removed in linear friction welding process,the high cycle fatigue strength of the joint can reach more than 90% of that of the base metal.