Research on local corrosion behavior of thermo-mechanically affected zone in dissimilar AA2024/7075 friction stir welds
By Zhang, Chenghang; Huang, Guangjie; Liu, Qing
Published in Intermetallics
2021
Abstract
The aluminum alloys joints welded by friction stir welding (FSW) are usually fractured in or near the thermo-mechanically affected zone (TMAZ) of the welded zone, and different microstructural zones produced by FSW affect the corrosion resistance of the joints. In the present work, we performed the research on local corrosion behavior of the TMAZ in dissimilar AA2024/7075 joints by employing multiple characterization and measurement techniques. The results revealed that low corrosion resistance is presented in the AS-TMAZ and RS-TMAZ compared to the correspondent base materials (BMs) by electrochemical testing. Higher stored energy presents in the TMAZ (AS-TMAZ and RS-TMAZ) than the corresponding BMs, which is more susceptible to corrosion. Immersion test results indicate that localized corrosion in the TMAZ is more serious than that of the corresponding BMs. Corrosion pits are mainly related to the Al–Cu–Mg particles in AS-TMAZ and Al–Zn–Cu–Mg particles in RS-TMAZ which act as anode relative to the aluminum matrix.