EFFECT OF PRECIPITATE DISPERSION ON RECRYSTALLIZATION TEXTURE OF NIOBIUM-ADDED EXTRA-LOW CARBON COLD-ROLLED STEEL SHEET.

Abstract

The effect of precipitate dispersion on the development of annealing texture in an interstitial free steel was investigated using a Nb-added extra-low C steel. Size and dispersion of precipitates in a Nb-added extra-low C steel was widely changed using the same steel and keeping the grain size similar. Strong left brace 111 right brace recrystallization texture was developed in the specimen with coarse and sparse precipitates, but not in the specimen with fine and dense precipitates. Solute C dissolved from fine precipitates after cold rolling and during heating exists at the recovery stage and at the beginning of recrystallization in the specimen with fine and dense precipitates, but this effect cannot be considered as an important factor because of little change in left brace 110 right brace texture. However, independent of precipitate dispersion, left brace 111 right brace recrystallized grains recover faster than left brace 100 right brace oriented grains and left brace 111 right brace recrystallized grains nucleate in situ in the deformed matrices. Fine and dense precipitates strongly suppress the growth of recrystallized grain, and results in a decrease in left brace 111 right brace texture. Therefore a pinning effect of precipitates for grain boundary moving during recrystallization is considered to be the most important factor controlling the recrystallization texture in an interstitial free steel.