Nonequilibrium solidification in Fe-C-Al-Mn steel welds

摘要

The TRXRD measurements from the HAZ region of a Fe-C-Al-Mn steel spot weld showed incomplete formation of austenite during the heating cycle and the presence of some ferrite even at the highest temperatures. During the cooling cycle, the austenite transformed to ferrite. For the same conditions, the TRXRD results from the WM regions showed primary nonequilibrium austenite solidification. In contrast, primary ferrite solidification was observed in a slow cooled weld. The dendrite tip temperature calculations did not support the observed transition from primary ferrite to austenite solidification. However, possibility of such transition at large undercooling was in qualitative agreement with computational thermodynamic and kinetic models.