The inhibition of abnormal grain growth in weld nugget via in-situ intermetallic-particle formation during friction stir welding of AA6061

摘要

Abnormal grain growth (AGG) has been widely observed in many friction stir welded (FSW) joints during post welding heat treatment. Various ways have been reported in previous studies to control it for better mechanical properties, but most of them fail to eliminate this problem completely. In the current research, a new method has been invented and adopted in common FSW and proved to be very effective in limiting AGG. Both macroscopic observation and microscopic characterization were conducted to explain why it succeeded in dealing with AGG. A model was raised to demonstrate the in-situ reaction that took place in multi-pass FSW.