Effect of Chemical Composition and Thermomechanical Processing on Texture in Hot Bands of Ti and Ti+Nb Containing Ultra-low Carbon Steels

Abstract

The effect of carbon, Ti and Nb on the formation of hot band texture in ultra-low carbon steels was studied. The chemical compositions were selected so that two of the four steels were fully stabilized with respect to carbon and the other two were expected to have some carbon in solution under equilibrium conditions. The slab reheating temperature ranged from 1 200 to 1 280°C. The first deformation was applied with a 50% reduction to simulate the roughing pass at 1 150°C. The samples were then deformed with another 50% reduction at either 1 050 or 920°C. The crystallographic orientations of the resulting ferrite were presented in the form of so-called skeleton plots along the RD-, TD- and ND-fibers. The main texture found was the cube-on-corner, {111}‹110›, component. The rotated cube component, {001}‹110›, was also present but its intensity was always lower than the intensity of the cube-on-corner component. The presence of the cube-on-corner texture was explained by the large grain size in the starting as-cast ingots and by the heavy reductions per pass. The combination of low reheating temperature and low finishing temperature generated the highest ratio of {111}/{100}. Decreasing the carbon content from 35 to 17 ppm and adding 90 ppm Nb to a Ti-alloyed ULC steel further increased the {111}/{100} ratio.