UNDERSTANDING THE DEFORMATION MICROMECHANISM OF HIGH NITROGEN STEEL

Abstract

Effect of warm rolling at 400oc on microstructure and Texture is systematically studied. Microstructures of warm-rolled HNS at different reductions were studied using different characterization techniques. Twin fraction is calculated using line profile analysis for each strain. Texture evolution with rolling strain is also studied, To predict the evolution of texture and twin fraction. the VPSC simulations are performed and compared with the experimentally obtained texture evolution and twin fraction. Through the microstructure study, after warm rolling, there was no sign of presence of different phase other than austenite and no deformation-induced transformation detected. Trend of increasing stacking fault probability with rolling strain ensured planar slip as one of the deformation micro mechanism. In microstructures of lower rolling strains heterogeneous deformation among the grains was observed and, at medium and higher rolling strains twins were seen growing across the grains. Twin fraction was calculated by performing the line profile analysis for each rolling reduction. VPSC model has successfully predicted the G and B orientation in 30% and 50% rolling strains. However, It has also predicted the Cu and S orientation in 50% rolling strains. However, the Cu and S orientation has not been predicted in case of 30% rolling strain. Twin fraction trend is successfully predicted by VPSC model, which shows the efficacy of VPSC model.