Abstract
Friction stir welding technique possesses a lot of features such as the formation of a fine-grained microstructure in the welded zone. Therefore, the friction stir welding process is expected to be a microstructure refinement method for crystalline materials. Many researchers have been paid attention to this as a microstructure control method for variety of alloys ; it is now called Friction Stir Processing (FSP). We have applied this joining method to 7075-T6 alloy as a novel microstructure control method. It was found that initial microstructure was altered considerably by the process; in particular, grains in the stirred zone were refined to very fine and equiaxial ones. We discussed a probable mechanism of the microstructure evolution with the present experimental results.
