Verification of numerical model to predict microstructure of austenitic stainless steel weld metal using synchrotron radiation and trans varestraint testing

Abstract

A numerical model to predict the microstructure of austenitic stainless steel weld metal is proposed, and spatially resolved X-ray diffraction measurements using synchrotron radiation have been carried out for Fe–20Cr–(9·8–14·4)Ni weld metals, quenched in liquid Sn, to verify the validity of the numerical model. X-ray diffraction analysis of Fe–20Cr–11·5Ni quenched weld metal, solidifying in the ferritic–austenitic mode, showed that the secondary γ phase crystallised in a eutectic growth mode down to a temperature drop of 6 K from the initiation of solidification. Also, from X-ray diffraction analysis of Fe–20Cr–12·7Ni quenched weld metal, which solidified in the austenitic–ferritic mode, it was found that the secondary δ phase crystallised in a eutectic growth mode within the temperature drop range between 15 and 21 K from the initiation of solidification. The crystallisation temperatures predicted by the numerical model for secondary γ and δ phases in Fe–20Cr–11·5Ni and Fe–20Cr–12·7Ni weld metals agreed with experimental data. Furthermore, it was found that the effect of Ni content on the solidification cracking susceptibility of Fe–20Cr–(9·8–14·4)Ni weld metal, determined via trans varestraint testing, agreed with the results calculated using the model. These agreements support the validity of the developed numerical model.