The recrystallization behavior of low carbon steel in high speed hot rolling has been investigated in relation to the strain distribution through the thickness. Sheet specimens with the size of 2×20×250mm were rolled between 650 and 850°C at the rolling speed of 20m/s without lubrication. The rolled specimen was quenched into water with a holding time ranging from 3 to 250ms. The redundant shear strain caused by friction forms severely sheared region beneath the surface. The width of the severely sheared region decreases and the maximum shear strain increases with lowering rolling temperature.
A band o f extremely fine recrystallized grains (d=2-10μm) is formed in the severely sheared region when effective strain exceeds a critical value which is dependent on rolling temperature. Recrystallized grains appear even in the sheet quenched after a short holding time of 3ms. The recrystallized grain size is strongly dependent on Zener-Hollomon parameter Z₀ at the midthickness of the sheet, and is independent of effective strain and initial grain size. It can not be made clear from the present experiment whether this recrystallization occurs dynamically or statically. However, the structural features of these recrystallized grains suggest that they are dynamically recrystallized ones.