扫描振镜激光TC4钛合金焊接性能及熔池流动行为  

Welding properties and molten pool flow behavior of TC4 titanium alloy by oscillating galvanometer laser

作　　者：陈波 孟正[1] 马程远 席鑫 王昕欣 檀财旺 宋晓国 CHEN Bo;MENG Zheng;MA Chengyuan;XI Xin;WANG Xinxin;TAN Caiwang;SONG Xiaoguo(Shandong Provincial Key Laboratory of Special Welding Technology,Harbin Institute of Technology,Weihai,Weihai 264209,China;State Key Laboratory of Advanced Welding and Connection,Harbin Institute of Technology,Harbin 150001,China;Department of Mechanical Engineering,University College London,London SW75 NP,United Kingdom)

机构地区：[1]哈尔滨工业大学(威海)山东省特种焊接技术重点实验室,威海264209 [2]哈尔滨工业大学先进焊接与连接国家重点实验室,哈尔滨150001 [3]伦敦大学学院机械工程系,伦敦SW75NP

出　　处：《航空学报》2022年第4期431-443,共13页Acta Aeronautica et Astronautica Sinica

基　　金：国家重点研发计划(2018YFB1107900)。

摘　　要：钛合金广泛应用于飞行器及航空航天发动机,激光焊是连接钛合金的优异焊接方法,目前主要问题是气孔导致的接头性能降低。扫描激光能显著改善激光焊接过程中的匙孔行为及熔池流动状态,从而降低气孔率、细化晶粒,最终提高接头性能。采用光纤激光器对4 mm厚TC4钛合金进行扫描振镜激光焊接,对比分析了以0.4 mm为步长、0.4~1.6mm扫描幅度扫描前后的焊缝成形、力学性能、晶粒细化程度、熔池流动与匙孔行为。结果表明圆形扫描路径下,激光功率为4kW、焊接速度为1.2m/min、离焦量为0、扫描频率为100Hz、扫描幅度为0.8mm时,匙孔型气孔受显著抑制,且对应的接头抗拉强度最高,为1025.03MPa,达到了母材的96%。与无扫描光束相比较,扫描幅度为0.8mm的接头上部平均晶粒面积减小了65%;圆形扫描的加入使熔池流动具有方向性,同时扫描激光能扩大并稳定匙孔,减少飞溅与气孔。Titanium alloys are widely used in aircraft and aerospace engines.Laser welding is an excellent welding method for joining titanium alloys,and the main problem currently existing is the degradation of joint performance due to porosity.Oscillating laser can significantly improve the keyhole behavior and molten pool flow state,thereby reducing porosity and refining grains,and eventually improving the joint properties in laser welding.Fiber laser was used to join the 4 mm thick TC4 titanium alloy using oscillating laser welding,and the weld formation,mechanical properties,grain refinement,molten pool flow and keyhole behavior before and after oscillating by 0.4 mm steps from 0.4 mm to 1.6 mm oscillating amplitude were compared and analyzed.The results show that keyhole-induced pores were significantly suppressed at a laser power of 4 kW,welding speed of 1.2 m/min,off-focus amount of 0,oscillating frequency of 100 Hz and oscillating amplitude of 0.8 mm,and the joint obtained can achieve the highest tensile strength of 1025.03 MPa,which is 96%of that of the base material.Compared to the beam without laser oscillating,the upper grains of the joint with an oscillating amplitude of 0.8 mm were refined by 65%.The presence of circular laser oscillating caused the molten pool to be more stable,and gave directionality to the molten pool flow while the oscillating laser enlarged and stabilized the keyhole,reducing spatter and porosity.

关 键 词：激光焊接 扫描激光 力学性能 晶粒细化 熔池流动 钛合金 

分 类 号：V252.2[一般工业技术—材料科学与工程]