Microstructural evolution and corrosion behavior of GH3536 superalloy fabricated by laser metal deposition following different aging heat treatments

The influences of aging heat treatment on the microstructures, passive films, and corrosion behavior of LMD-processed and wrought GH3536 alloy were investigated through electrochemical tests and surface characterization methods. The research results show that samples produced by LMD processing exhibit lower corrosion resistance than those produced by wrought processing. This is largely due to differences in texture and grain size resulting from the different fabrication methods. In particular, the LMD-processed sample, with its (200) orientation texture, promote the formation of porous Ni-oxides at the cost of compact Cr-oxides in the passive films. Fortunately, as the aging temperature increases, the corrosion resistance of LMD-processed samples significantly is significantly improved (Corrosion resistance: LMD-processed-HT3 > wrought-HT1). This improvement is closely linked to the solid solution of Cr23C6 and sigma phases in the matrix, which also results in enhanced stability and integrity of passive films.