Discussing the precipitation behavior of σ phase using diffusion equation and thermodynamic simulation in dissimilar stainless steels

This study performed a precipitation examination of the a phase using the Vitek diffusion equation and thermodynamic simulation in dissimilar stainless steels during multi-pass welding. The results of the experiment demonstrate that the diffusion rates (D-Cr(delta) and D-Ni(delta)) of Cr and Ni are higher in delta-ferrite than (D-Cr(gamma), and D-Ni(gamma)) in the gamma phase and that they facilitate the precipitation of a phase in the third pass fusion zone. When the diffusion activation energy of Cr in delta-ferrite is equal to that of Ni in delta-ferrite (Q(d Cr)(delta) (sic) Q(d Ni)(delta)), phase transformation of the delta --> sigma can be occurred. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.