Metal dusting of Inconel 625 obtained by laser beam melting: Effect of manufacturing process and hot isostatic pressure treatment

Abstract : Metal dusting resistance of Inconel 625 alloy obtained by laser beam melting (LBM), compared to wrought alloy 625 was assessed during 9 500 h at 610 °C. Whatever the manufacturing process, the mass variations were very small when the systems were ground thanks to the formation of a uniform protective chromia layer. However, the high surface roughness was shown to be detrimental as the waviness favoured the local formation of an unprotective spinel oxide. Hot isostatic pressure (HIP) treatment recrystallized the alloy and increased its grain size. This reduced chromium diffusion towards the surface, explaining the poorer resistance of the LBM + HIP system.