Effect of Al Content on r-Value and Recrystallization Texture of B-Bearing Al-Killed Steel Sheets

Abstract

It has been demonstrated that boron (B) had a beneficial effect on the mechanical properties of continuously annealed Al-killed steel sheets. However, the effect of Al content on r-value in the B-bearing steels has not been well discussed yet. In this study, the effect of Al content on r-value and recrystallization texture formation was investigated for laboratory-melt B-bearing low C Al-killed steel sheets. The r-value of continuously annealed B-bearing steel increased with decreasing Al content under the same grain size. In the steels with lower Al (Al=0.005%) content, the carbide coarsening in hot-rolled sheet was more significant as compared to those with higher Al (Al=0.055%) content. The recrystallization temperature was lowered with decreasing Al content, and the development of //ND components was accelerated while that of //ND components was retarded. Since the increase in Al content accelerates AIN precipitation in hot-rolled sheets, B might remain as in solution and segregate to grain boundaries. On the other hand, the reduction in Al content causes preferential precipitation of BN in hot-rolled sheets. The improvement of r-value by reducing Al content in B-bearing low C steels was caused by the development of //ND components which reduced by solute B.