Effect of microalloying with V and Ti on the microstructure and properties of electron beam welded thick high-Mn TWIP steel plates

Abstract

In the present work, thick high-Mn TWIP steel plates with/without the addition of V and Ti were butt welded by electron beam welding (EBW) to study the effect of V and Ti on the microstructure and properties of the welded joints. It was observed that the fusion zones (FZs) of the joints consisted of two types of solidification structures, i.e. columnar dendritic structure and cellular structure. Strong texture component characterized by ⟨100⟩∥X-axis was developed by epitaxial growth of these solidification structures along ⟨100⟩ direction. Microalloying with V and Ti significantly refined the microstructure and led to the precipitation of secondary phase particles, which dramatically enhanced yield strength (YS). γ-ε transformation occurred when the REF (reference) grade joint was subjected to impact deformation at cryogenic temperature, which led to the decrease in Charpy impact energy. The addition of V and Ti reduced the occurrence frequency of internal defects, particularly the microsegregations of C and Mn, which contributed to the improvement of corrosion resistance.