Effect of microstructural features on the planar anisotropy of the R-value in Cu-added bake-hardenable steels

This study was focused on investigating the effect that microstructural features have on the planar anisotropy of the plastic strain ratio (R-value) in Cu-added bake-hardenable (BH) steel. Ti-Nb-added BH steel was used for a comparison of microstructural features and their effects on the planar anisotropy of an R-value. Quantitative and qualitative analyses of the precipitates for two hot-rolled BH steels were conducted via TEM. An EBSD technique was used to analyze the evolution of the microtexture in consecutive manufacturing processes of hot-rolling, cold-rolling and annealing. Microstructural features in cold-rolled specimens were explained in terms of the type of deformed grains. The stored energy distribution that developed in subgrains was used to explain the relatively high planar anisotropy of the R-value for Cu-added BH steel. A visco-plastic self-consistent (VPSC) polycrystal model was employed to calculate the planar anisotropy of the R-value for annealed BH steels.