Effects of Cooling Rate during Solidification and Charging Temperature Prior to Hot-rolling on Mechanical Properties of Cold-rolled Sheet Steels with Deep Drawability

Abstract

A study has been made of the effects of the cooling rate during solidification and the charging temperature prior to hot-rolling on the mechanical properties of cold-rolled sheet steels with deep drawability. The r-value deteriorates abruptly as the charging temperature decreases below 900°C in the batch-annealed low carbon Al-killed steel sheet hot-rolled from the ingot solidified in cast-iron mold to simulate the solidification condition of thin-slab casting, while r-value remains high even at the charging temperature of 600°C in sand mold sample to simulate the solidification condition of conventional continuous casting.
Ther-value of continuously annealed extra-low carbon Ti-bearing steel sheet hot-rolled directly from the ingot solidified in the cast-iron mold is about 2.0 and is same as that of sand mold sample. However, with decreasing the charging temperature, the r-value of sand mold sample decreases, whereas that of castiron mold sample remains almost constant.