Relationship of the Microstructure and Toughness of the Coarse Grain Heat-Affected Zone of TiNbV Microalloyed Steels Based on Electron Backscatter Diffraction Analysis

Abstract The microstructure evolution and impact toughness of the coarse grain heat-affected zone (CGHAZ) TiNbV microalloyed steels were investigated by using a thermal simulation test. samples treated with various simulated welding cycles. phase constituents sizes analyzed electron backscatter diffraction analysis. CGHAZ consisted ferrite, acicular pearlite, bainite. have higher under lower heat input. This is because dominated volume fraction high-angle boundaries ferrites. presence bainite coarsening grains are two key factors deteriorating steels. sharply increased as input increased, leading to decrease in CGHAZ. For input, both severe size content would result poor toughness.