Abstract In this work, the isothermal reaustenitization on a chemically homogeneous weld metal has been investigated with the purpose of studying the general trend of the kinetics. For this reheated weld metal, bainitic ferrite can form from small-grain austenite. In order to understand the reaustenitization behavior that occurs in the multirun weld deposits, an experiment was designed to study the mechanism of austenite growth from a microstructure consisting of bainitic ferrite and residual austenite. It was found that the rate of ferrite → austenite transformation increased with increasing austenitization temperature and that for low austenitization temperatures, substitutional alloying elements redistributed during the ferrite → austenite transformation, even in a very short period of time. The degree of redistribution of alloying elements during transformation decreased with increasing austenitization temperature. Eventually the partition coefficients for substitutional alloying elements equaled unity, as the austenitization temperature rose to close to the fully austenitic temperature. The results emphasize the fact that the mechanism of austenite growth depends on the driving force for austenitization.