Structure and Texture Formation During Single and Double Cold Rolling and Annealing Processes for Nb plus Ti Added Interstitial-Free Steels

The structure and texture formation for single cold rolling (SCR) with annealing and double cold rolling (DCR) with annealing were investigated based on optical microscope and X-ray diffraction (XRD) with a Nb+Ti bearing interstitial free (IF) steel. The results indicated that DCR recrystallization grain was smaller than that of SCR sample and double cold rolling process resulted in better mechanical properties than those resulted from single cold Tolling process with the same total reduction conducted. The plastic strain ratio increases from 2.23 for single cold rolling process to 3.2 for double rolling process. The fish-bone structure was observed in all SCR and DCR samples. DCR annealed sample is made up of equiaxed grains of almost uniform size, whereas SCR annealed sample shows a duplex grain structure, consisting of both large and small-sized grains. (Ti+Nb)C and Fe(Ti+Nb)P type precipitates were very rarely observed in SCR annealed and DCR annealed steels. The intensity of {111}//ND for the DCR annealing was higher than that for SCR annealing.