Research on the corrosion behavior of double-side friction stir welded 6082Al alloy thick plate

摘要

In order to study the influences of microstructures on corrosion behavior of double-side friction stir welded 6082Al thick plate. The corrosion behavior was firstly clarified by potentiodynamic polarization and exfoliation corrosion (EXCO) tests. The microstructures before and after corrosion were identified by optical microscopy (OM), SEM and transmission electron microscope (TEM). The results showed that the corrosion resistance of heat-affected zone (HAZ) and base material (BM) was lower than those of thermo mechanically affected zone (TMAZ), top of NZ and middle of NZ. Bottom part of NZ was the most severe corroded zone. Intergranular corrosion along grain boundaries was the dominant corrosion type in BM, HAZ, TMAZ and bottom of NZ, while the top and middle part of NZ were susceptibility to pitting. The corrosion resistance decreased with the increase of weld pass. The precipitates mainly precipitated in NZ of the first pass and HAZ of both two passes during double side friction stir welding (FSW) due to the over aging process, which deteriorated the corrosion resistance.