| 摘要 |
<p>Disclosed are a high strength hot-rolled steel sheet which is manufactured to be a low alloy-based steel sheet in a reduced process and have super high strength reaching 1470 MPa or greater of tensile strength (TS) and excellent bending machinability, and a manufacturing method thereof. The manufacturing method of the high strength hot-rolled sheet comprises steps of: (a) reheating a slab plate at the slab reheating temperature of 1200-1300°C or less; (b) finishing the reheated slab plate by hot-rolling the reheated slab plate at the finish delivery temperature (FDT) of 860-920°C; and (c) coiling the hot-rolled slab plate after cooling the slab plate down to the coiling temperature of 150°C, wherein the slab plate comprises: 0.18-0.22 wt% of carbon (C); 0.05-0.30 wt% of silicon (Si): 0.6-0.8 wt% of manganese (Mn); 0.05 wt% or less phosphorus (P); 0.005 wt% or less of sulfur (S); 0.2-0.4 wt% of chrome (Cr); 0.001-0.005 wt% of boron (B); and the remainder consisting of Fe and inevitable impurities.</p> |
