PROCESS FOR PRODUCING HOT-DIPPED HOT-ROLLED STEEL SHEET

摘要

A steel sheet produced by casting a steel containing at least 0.03 mass% carbon, at least 0.02 mass% silicon, at least 0.15 mass% manganese, and at least 0.001 mass% calcium by the thin-slab continuous casting method and hot-rolling the cast is oxidized by heating it at a heating rate of 25 °C/sec or higher to a maximum steel-sheet temperature of 550-650°C, excluding 650°C, for at least 15 seconds. The sheet is then reduced by heating it to a maximum steel-sheet temperature of 700-760°C in such a manner that the time period in which the steel sheet temperature is 570°C or higher is 25-45 seconds. Thereafter, the steel sheet is plated by hot dipping to produce a hot-dipped hot-rolled steel sheet.