The improvement of corrosion resistance of sensitized alloy 82 welds using laser surface melting

The corrosion resistance of sensitized Alloy 82 welds is improved by laser surface melting (LSM) with a continuous CO₂ laser beam. The effects of the LSM treatment on the segregation of impurities in the matrix and the precipitation of carbides at the grain boundaries are systematically explored. The observation results show that the LSM process results in the formation of a rapidly solidified surface layer with a thickness of approximately 160-180 μm. In addition, the corrosion test results show that the LSM treatment improves the resistance of the weld to both intergranular corrosion (IGC) and pitting corrosion. The improved corrosion resistance can be attributed to a higher proportion of low-Angle boundaries (2∼15°) in the solidified microstructure, the elimination of Cr-carbide precipitates in the matrix, and the suppression of Cr-depletion zones at the grain boundaries. Overall, the results confirm the effectiveness of LSM treatment for the in-situ repair and corrosion resistance restoration of Alloy 82 welds.