フェーズフィールド法による Ni 基超合金付加製造における凝固偏析予測

抄録

Abstract: Solute segregation significantly affects material propert ies and is an essential issue in powder-bed fusion（PBF）type additional manufacturing（AM）of nickel-based superalloys. In the present study, we have investigated the effects of solidification conditions of temperature gradients and solidification rates on segregation behavior in Hastelloy-X Ni-based superalloy using multi- phase field（MPF）simulation. To evaluate liquation crack susceptibility, the solidus temperatures were calculated using predicted compositions of the segregated regions. MPF simulations revealed that the segregations of Mo and Cr and the depletion of Co become more remarkable with increasing cooling rate, and this solute segregation causes the decrease of a solidus temperature up to 17.7 K. In the PBF type AM process, metallic powders are solidified under a unique condition of a high temperature gradient G and a high solidification rate R, and suggested that strong solute segregation and liquation cracks occur.