HOT-ROLLED STEEL SHEET WITH MEDIUM CARBON AND METHOD OF MANUFACTURING THE SAME

摘要

PURPOSE: A medium carbon hot-rolled steel sheet and a manufacturing method thereof are provided to allow the same to have hardenability proper to a hollow material and fine grains through alloy elements and process controls. CONSTITUTION: A manufacturing method of a medium carbon hot-rolled steel sheet includes: a hot-rolling a slab sheet material at a finish rolling temperature of 850 to 900°C; and a step of cooling the hot-rolled sheet material, and then coiling the sheet material at a temperature of 600 to 680°C. Before the step of hot-rolling the sheet material, the sheet material is reheated at a temperature of 1150 to 1250°C for one to three hours. The sheet material comprises 0.22 to 0.27 wt% of C, 0.15 to 0.25 wt% of Si, 1.6 to 2.0 wt% of Mn, below 0.03 wt% of P, below 0.01 wt% of S, 0.001 to 0.0025 wt% of B, and remnants Fe and inevitable impurities.