TA5钛合金万瓦光纤激光焊接工艺研究

Study on high power fiber Laser welding technology of TA5 titanium

摘要:

采用10mm TA5钛合金，开展了万瓦级光纤激光焊接工艺研究。焊接过程高速摄影表明，当激光功率达到3～4KW时，羽辉严重，飞溅及烟尘增加明显；不同功率焊缝截面形貌试验表明，较低焊接功率时，焊缝截面呈“楔形”，当激光功率达到6千瓦以上时焊缝截面过渡为“漏斗形”。采用激光功率为10～11KW，焊接速度为1100～1500mm/min的工艺得到成型优良的“小孔型”焊接试板，焊缝变为具有较大深宽比的典型的高能束形貌,深宽比达到2:1，对焊缝进行射线和渗透检测，满足无损检测标准要求；对焊接接头进行力学性能和工艺性能开展测试，结果表明：焊接接头强度可达800Mpa，弯曲测试能够满足标准，断口韧窝明显，为韧性断裂；金相测试显示，焊缝区截面为“束腰”形貌，柱状晶区明显，各柱状晶区有明显的竟争生长模式。焊缝区主要为锯齿状α+点状β。硬度检测显示，焊缝区相比母材硬度略有升高，热影响区硬度最低，满足钛合金接头硬度要求。

Abstract:

The laser welding processing of 10mm thickness TA5 titanium alloy by using10KW high power fiber laser was syudied. The high speed photography shows that when the laser power reaches 3~4KW, the plume become serious, and the splash and soot increase obviously. The weld metallography test shows that the weld section is "wedge-shaped" when the laser power is low, while the weld section becomes "funnel shaped" when the laser power is more than 6KW.When the laser power is set 10KW~11KW ,and the welding speed is 1100~1500mm/min，an excellent "Key-holding" welding joint is obtained，and the welding seam become typical high-energy beam joint shape with a big ratio of depth to width is up to 2:1. RT and PT test of the weld seam show that NDT standard can be met.The mechanical test shows that the strength of the welded joints can reach 800Mpa, and the bending standard can be met，The fracture dimple is obvious, which indicates a ductile fracture. Metallographic test shows that the section of weld zone is "girdle-shape" morphology and the columnar crystal zones are obvious, with each columnar crystal zone showing obvious competitive growth mode. The weld zone is mainly serrated α+punctate β. The hardness test shows that the hardness of the weld zone is slightly higher than that of base metal, and the hardness of heat-affected zone is the lowest, which meets the hardness requirements of titanium alloy joint.