PURPOSE: To produce a steel material with less micro-segregation by maintaining the molten steel prior to charging into a mold near the solidification temp., allowing said steel to solidify at cooling rates higher than specific rates then subjecting the same to ordinary hot rolling.
CONSTITUTION: The molten steel prior to charging into a mold is maintained at temps. within 10°C from the solidification temp. and is allowed to solidify at ≥10°C/min cooling rates, after which it is subjected to ordinary hot rolling. Then, the grain sizes of micro-segregated grains are reduced to about ≤300μ, and said grains are practically harmless. In other words, no micro-segregated grains are observed in the cracked parts. Micro-segragated lines are made unharmful at the same time.
MISUMI HIDEYUKI
MIZOGUCHI SHIYOUZOU
