Study of microstructural evolution of friction taper plug welded joints of C–Mn steels

Abstract

This paper describes the microstructural evolution of friction taper plug welded joints of C–Mn steels. Experimental and numerical analyses included calculations based on Calphad and continuous cooling transformation curves, and characterisation techniques. The studied friction taper plug welded joint contains three macroregions: plug material, thermomechanically affected zone (TMAZ) and base material. The thermomechanical conditions imposed in the studied friction taper plug welded joint precluded the formation of a heat affected zone. However, seven subregions were identified within the TMAZ region and details are discussed. The interface zone is found in the TMAZ region, where the most relevant phase transformations take place. It is suggested that the phase transformations in TMAZ region depend on local conditions, such as chemical composition, deformation rate, thermal history and the previous thermomechanical history of the parent materials.