Fe-bearing intermetallics transformation and its influence on the corrosion resistance of Al–Mg–Si alloy weld joints
Xiaming Chen, Qipeng Dong, Zhen-Guang Liu, Xiaonan Wang, Qingyu Zhang, Zengrong Hu, Hiromi Nagaumi
Abstract
This work investigated the transformation of Fe-bearing intermetallics and its influence on the corrosion behavior of Al–Mg–Si alloy weld joints. The results showed that the size and type of Fe-bearing intermetallics determined the pitting corrosion resistance of weldment regions. The partially melted zone (PMZ) suffered most serious corrosion attack, because of the formation of coarse needle-like β-AlFeSi. The heat-affected zone (HAZ) immediately behind the PMZ (HAZ-Ⅰ) experienced a complete transformation of β-AlFeSi into α-AlFeSi, but in the rest of the HAZ (HAZ-Ⅱ) was not sufficient for this transformation. Therefore, the HAZ-Ⅰ was more resistant to pitting corrosion than HAZ-Ⅱ.