Research on the Corrosion Resistance of Gh4738 Ni-Based Superalloys Treated by Laser Surface Remelting

Abstract

GH4738 Ni-based superalloys was modified by laser surface remelting (LSR) with the power of 500W, 600W and 700W. The microstructure, boundary fraction, and dislocation density were analyzed, and the composition and compactness of the passive film were studied. The corrosion properties were evaluated, in an attempt to reveal the corrosion mechanism. The results show that the corrosion resistance of LSR-treated Ni-based superalloys increases in the order of 700W > 600W > 500W > as-cast in accordance with the sequence of low-∑CSL boundary fraction and the protective ability of the passive film. The primary reason for the 700W specimen exhibiting the strongest corrosion resistance is its highest fraction of low-∑CSL boundaries, and the passive film is the most compact and has the highest Cr2O3 content. Our research results provide an in-depth understanding of the intrinsic relationships between the fraction of low-∑CSL boundaries, the composition and compactness of the passive film, and the corrosion resistance of LSR-treated Ni-based superalloys at different power levels.

Keywords: Ni-based superalloys, Laser surface remelting, corrosion resistance, Passive film