Examination of toughness and solidification cracking on 12% Cr martensitic stainless steel weld metal with Ni added

Abstract

Toughness and weld solidification cracking in the weld metal of martensitic stainless steel containing Ni were investigated. The weld metal of martensitic stainless steel with low C and proper Ni can be applied without PWHT (Post weld heat treatment) due to the microstructure mainly consisting of soft martensite including retained austenite resulting in enough toughness though PWHT is necessary in conventional one because of high hardness as weld condition. However by the addition of Ni the susceptibility to weld solidification cracking can be higher. As the experimental evaluation was conducted in terms of solidification cracking test and Charpy impact test using the weld metal of 12/16%Cr-3/14%Ni steels. As the results the slight amount of ferrite phase caused the lowering of notch toughness within the weld metal including the same level of retained austenite. The excess Ni addition to decrease ferrite phase in solidification process increased the susceptibility to solidification cracking in during solidification process by austenite phase. In conclusion optimum Cr and Ni content to achieve the both of low susceptibility to solidification cracking and high toughness was clarified.