HOT ROLLED STEEL SHEET EXCELLENT IN COLD WORKABILITY AND PRODUCTION METHOD THEREFOR

摘要

PROBLEM TO BE SOLVED: To uniformize micro structure and soften material quality of a hot rolled steel sheet before being cold-rolled and containing relatively large C content.SOLUTION: There is provided a hot rolled steel sheet that has been hot-rolled in the temperature range of Ar3 point °C to 600°C and that has micro structure containing ferrite of 20% or more by volume fraction and is excellent in cold workability. The hot rolled steel sheet is produced by (i) cooling the hot rolled steel sheet that has been hot-rolled in the temperature range of Ar3 point °C to 600°C to 300°C or less, heating the hot rolled steel sheet to 400°C to 700°C just before winding it and winding it as it is or (ii) cooling the hot rolled steel sheet that has been hot-rolled in the temperature range of Ar3 point °C to 600°C to 300°C or less and winding it, then rewinding, heating it to 400°C to 700°C and winding it.SELECTED DRAWING: Figure 1