Research on microstructure and stratification mechanical properties of friction stir welded 2A21 aluminum alloy thick plates
WANG Pengfei;ZHAO Yong;YAN Keng;LIU Chuan;Provincial Key Lab of Advanced Welding Technology,Jiangsu University of Science and Technology;
Nineteen mm-thick 2A21 aluminum alloy was welded by friction stir welding. After welding process,the microstructure of different zones of joint had been observed and analyzed. The tensile test and measurement of microhardness were conducted to evaluate the properties of joint. The results show that it contains fine and equiaxed grains in the shoulder affected zone and weld nugget zone. Near the bottom of the nugget zone on the retreating side,it contains grains of different sizes in the partial recrystallization zone. The maximum tensile strength locates at the top,which is 348 MPa. The strength is 76. 5% of that of the base metal and the fracture occurs at the boundary between the shoulder affected zone and thermo-mechanical affected zone on the retreating side. The minimum strength locates at the bottom and the fracture is found in the partial recrystallization zone. The microhardness curve shows a "W"shape,in which the maximum value lies in the nugget and the minimum value lies in HAZ. Through out the thickness microhardness at the top is greater than that at the bottom.