Effect of post-weld heat treatment on inhomogeneity of mechanical properties and corrosion behavior of rotary friction welded 2024 aluminum alloy joint

The effects of different aging treatment conditions on inhomogeneity of mechanical properties and corrosion behavior of rotary friction welded (RFWed) AA2024 joints were studied by artificial and natural aging treatment. The sliced samples at the center, 0.25R, 0.5R and 0.75R positions were taken along the radius of RFWed joint. After artificial aging and long-term natural aging treatment, the tensile strength and corrosion resistance in different positions of joint tended to be homogeneous. Furthermore, the distribution of elements existed in the interior of grain and grain boundary was homogeneous after artificial aging, which reduced the tendency of intercrystalline corrosion. And pitting corrosion occurred at dynamic recrystallization zone (DRZ), thermomechanically affected zone (TMAZ), heat affected zone (HAZ) and base metal (BM). The order of corrosion resistance of each region was inferred from the electrochemical parameters as BM > TMAZ > HAZ > DRZ. With the prolongation of natural aging time, the best corrosion resistance occurred in BM, while the corrosion types of DRZ, TMAZ and HAZ gradually changed from pitting and intergranular corrosion to pitting corrosion mainly.