Microstructure evaluation and mechanical properties of friction stir welding of accumulative roll bonded AA۲۰۲۴/AA۵۰۸۳ composite strips

In this research, the ultrafine-grained (UFG) composite of AA۲۰۲۴ and AA۵۰۸۳ aluminum alloys was made by accumulative roll bonding (ARB) process and butt-welded by friction stir welding. Friction stir welding (FSW) is the best method for the joining of UFG strips.Microstructural investigations were performed by optical microscope and transmission electron microscope in the stir zone (SZ), thermo-mechanically affected zone (TMAZ) and heat affected zone (HAZ). The fine recrystallized structure was determined in the weldment. The high strength of the weld was due to the strengthening mechanisms of grain boundaries, nano-meter size precipitates and solid solution strengthening, so that the homogenous distribution of precipitates caused very good ductility in FSWed strips. The high hardness of the SZ was caused by the formation of new equiaxed grains and fine precipitates, and also the decrease in the hardness of the HAZ was due to the dissolution and coarsening of T-phase precipitates.

کلیدواژه ها:

Accumulative roll bonding ، ultrafine-grained composite ، friction stir welding ، equiaxed grains ، continuous dynamic recrystallization