热源同轴辅助搅拌摩擦焊热过程数值分析

Numerical Analysis of Thermal Behavior in Heat Coaxially Assisted Friction Stir Welding

针对空间环境焊接修复与组装需求,提出热源辅助固相焊接方法,以避免高真空与微重力空间环境的不利影响。该辅助热源采用激光同轴加热中空搅拌头,间接为焊缝提供热输入。在对激光束于搅拌头小孔中的反射与吸收行为进行分析的基础上,建立复合焊接热源模型,对复合焊接过程温度场进行了数值计算。分析结果表明,加入激光辅助热源能将焊缝最高温度从394℃提高到511℃,激光热量主要加热搅拌针周围的材料,具有局部加热的特点;在相同条件下,辅助热源提高了焊接热输入,焊缝金属软化程度增加,为降低焊接作用力和提高焊接速度提供条件;仿真结果与实测结果对比的一致性说明复合焊接分析模型能够用于预测焊接过程的温度场,为优化工艺参数提供理论依据。

According to the requirements of repair welding and assembly in space,a welding method of heat assisted solid-state welding was proposed to avoid the adverse effects of high vacuum and microgravity environment.The assisted heat source using laser heated hollow welding tool coaxially provided heat for welding.On the basis of the analysis of the behavior of laser energy absorbed in the small hole,the model of hybrid welding was established.The temperature field of hybrid welding process was calculated and analyzed using finite element method.The results showed that,laser heat source could increase the maximum temperature of FSW welds from 394℃ to 511℃,and the heating effect mainly focused on the material around the pin.The simplified model of laser-assisted heat was a good simulation of hybrid weld.With the same heat input,hybrid weld could improve the welding speed.Comparison between simulation results and measured results showed that,the establishment of the model was rational,and could be used to predict the hybrid welding temperature field,and to provide a theoretical basis for the optimization of process parameters