搅拌摩擦焊接中搅拌头自优化机理

摘要

基于网格重剖分技术建立了6061铝合金工件的搅拌摩擦焊接过程的完全热力耦合模型.利用Archard公式计算搅拌头的磨损量,提取工件温度场和应变率基于蒙特卡洛法模拟焊后工件截面的再结晶晶粒尺寸及分布规律.研究发现,随着搅拌头磨损程度的增加,搅拌头受力减小,提高了搅拌头的服役寿命,同时应变率随搅拌头磨损量的增加而增加,使再结晶形核率增加,并使搅拌区内晶粒更加细小,适当的磨损对搅拌头服役和焊接质量均有一定程度的优化.过量磨损则会导致焊缝质量下降.%Based on the adaptive re-meshing technique,the fully coupled thermo-mechanical model of friction stir welding of AA6061 is established.The wear loss of welding tool is calculated by Archard equation.The temperature curve and equivalent strain rate are exacted to calculate the grain size and distributions in recrystallization after weld by use of Monte Carlo method.Results indicate that the equivalent strain rate is increased with the increase of wear,which can lead to the increase of nucleation.The grain sizes in the stirring zone can be then decreased.The service life and weld quality can be increased by appropriate wear.Certainly,excessive wear can lead to the decrease of weld quality.