Abstract
It was clarified that the promotion of the crystallization of Chromium carbide during welding solidification by increasing C content was effective to decrease the solidification cracking susceptibility of fully austenitic weld metal with a large amount of Phosphorus. The decrease of solidification cracking susceptibility by increasing carbon content in Fe-(0.01-0.7)%C-25%Cr-50%Ni-0.1%P weld metal was confirmed using transverse varestraint testing and restraint weld cracking test. Also, γ/M7C3 eutectic phases were observed in the neighborhood of solidification crack on 0.7%C weld metal. In order to solve the mechanism of the decrease of solidification cracking susceptibility by the crystallization of Chromium carbide, a numerical model to predict the behavior of microsegregation during welding solidification was developed with notable features considering the competition of the crystallization between M23C6 and M7C3 eutectic phases and the coupling with thermodynamic database. It was found that the decrease of solidification cracking susceptibility on fully austenitic weld metal with 0.1% Phosphorus by increasing carbon content caused by the acceleration of the decrease of the amount of microsegregations by the promotion of the Cr based carbide crystallization.
