Abstract
The effect of hot rolling starting temperature on mechanical properties of Nb-containing low-carbon steels produced by continuous casting-direct rolling process was studied. Experiments were carried out by using a continuous casting machine and a hot strip mill at Hirohata works.
As a result, when the hot rolling starting temperature was at 1 020°C, yield point and tensile strength of the hot band produced by direct rolling process were lower than those by conventional reheat process. When the hot rollling starting temperature was at 1130°C and finishing temperature was lower than 850°C, tensile strength and toughness of the hot band produced by direct rolling process were almost same as those by reheat process.
In this condition, precipitates of Nb (C, N) were effectively formed during hot rolling, and these were usefull for grain refining.
