Behavior of (Ti, Nb)(C, N) complex particle during thermomechanical cycling in the weld CGHAZ of a microalloyed steel

This study aims to investigate the effect of deformation (stress and strain) on the coarsening kinetics of a (Ti, Nb)(C, N) complex particle during isothermal and continuous thermomechanical cycles in the weld coarse-grained heat-affected zone (CGHAZ) of a Ti + Nb microalloyed steel. Results in isothermal coarsening tests showed that the coarsening rate was enhanced by deformation under both compressive and tensile stress: it was enhanced mainly owing to the increased diffusivity of solute atoms. Then the compressive stress was found to be more effective than tensile stress. Interestingly, despite the increase in the coarsening rate, the mean particle size in the weld CGHAZ, after continuous thermomechanical cycle, decreased more than it did in the simple thermal cycle. This was because of enhancement of the precipitation of fine particles by increased precipitation kinetics under deformation.