Effect of particles on the dynamic recrystallization behavior of Al-V-N micro-alloyed medium carbon steel

Abstract

Using a Gleeble hot-deformation simulator, we have studied the dynamic recrystallization (DRX) behavior of AI-V-N micro-alloyed steel subjected to two different cooling conditions, i.e., air-cooling (AC) and water-cooling (WC), after solution treatment. The different prior-thermal treatment resulted in distinctively different DRX behavior of the steel. The DRX at a slow strain rate (0.01 s(-1)) was significantly retarded by dynamic precipitation of fine VCN particles; in contrast, the DRX was accelerated at a fast strain rate (5 s(-1)) due to coarse AlN particles, which were formed by rapid coarsening of static AlN particles during fast deformation. The activation energy for DRX was 420-480 kJ/mol, which was significantly larger than that of V-microalloyed steel. The peak and critical strains significantly deviated from the conventional exponential function of the temperature corrected strain rate. The grain size was refined from 130 mu m to 5-60 mu m by DRX and the dynamic precipitation appeared to be effective for grain size refinement. (C) 2012 Elsevier B.V. All rights reserved.