Prediction of microstructure and properties in the heat affected zone of HSLA-100 weldments

The objective of this study was to model the evolution of the microstructure and the resultant hardness in the heat affected zone (HAZ) of HSLA-100 steel weldments. The experimental HAZ results of Spanos et al., where four different weld thermal cycles, with two peak temperatures (1400 and 900°C) and two cooling rates (5 and 60 K s^–1), were emulated in a heating/quenching dilatometer, are compared with the results of three weld simulation modelsfor the decomposition of austenite. The three models are those of Kirkaldy and coworkers, Ion, Easterling, and Ashby, and Bhadeshia and co-workers. All of the models require the chemical composition, a thermal profile, and an austenite grain size measurement. All of the models gave excellent results for the fast cooling rates. Bhadeshia's model gave good results for one of the slower cooling rates, but not the other. Neither Kirkaldy's model nor that of Ion et al. was satisfactory for the slower cooling rate cases.