Effects of the Intercritical Rolling on Structure and Properties of Low Carbon Steel

Abstract

Recovery and recrystallization behavior of ferrite during and after intercritical roiling have been investigated in low carbon steel, using laboratory mill. The results obtained are as follows:
(1) Dynamic recrystallization of ferrite occurs in the intercritical rolling with such a high reduction as about 80 per cent.
(2) Dynamically recovered ferrite structure formed during the intercritical rolling is very stable as 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 the intercritical roiling, strong and tough steel can be produced by heating at reduced temperature, followed by the rolling both in the lower temperature range of austenite and subsequent intercritical range where the fraction of transformed ferrite is less than that of non-transformed antenite. It is also necessary, for this purpose, that the rolled products are air cooled or heat treated at the temperature below Ar₁. The total molling meduction being kept same, the properties of steel obtained by intercritical multipass rolling are nearly equivalent to those obtained by single pass rolling.