Recovery and recrystallization behavior of ferrite in low carbon steel during and after intercritical rolling have been investigated using a laboratory mill. The results obtained are as follows:
(1) Dynamic recrystallization of ferrite occurs in the intercritical rolling at a high reduction of about 80%.
(2) Dynamically recovered ferrite structure formed during intercritical rolling is very stable compared with that formed in the rolling below Ar₁.
(3) Fine ferrite-pearlite structure is obtained from austenite worked in the intercritical range.
Making use of these beneficial effects of intercritical rolling, stronger and tougher steels can be produced by reheating steels at lower temperatures, followed by rolling both in the low temperature range of austenite and intercritical range where the fraction of transformed ferrite is less than that of non-transformed austenite. It is also necessary, for this purpose, that the rolled products be air-cooled or heat treated at a temperature below Ar₁. If the total rolling reduction is the same, the properties of the steel obtained by intercritical multipass rolling are nearly equal to those obtained by single pass rolling.