Effect of niobium on recrystallization of ultralowcarbon cold-rolled automobile sheet steel

1. Recrystallization of steels after hot rolling with a low reeling temperature begins and ends at a higher temperature and a longer hold than in steels obtained with reeling at a higher temperature. 2. After hot rolling with a high reeling temperature the recrystallization of steel not bearing excess elements in the solid solution (Nb/C ef ≅1) begins and ends much more rapidly than recrystallization in the other steels. 3. After continuous annealing, the ferrite grains in steel with Nb/C ef ≅1 have a maximumsize, which is connected with the leading recrystallization of this steel. 4. The growth of ferrite grains in steel subjected to high-temperature reeling is accompanied by a decrease in the yield point and an increase in the specific elongation and coefficient of normal plastic anisotropy. Steels with Nb/C ef ≅1 have maximum mechanical properties.