| 摘要 |
<p>Disclosed are a high strength steel sheet and a manufacturing method thereof which can reduce manufacturing costs by reducing the added amount of a nickel element by controlling alloy elements and process conditions, and which can be utilized as a line pipe by obtaining excellent impact properties. The manufacturing method of the high strength steel sheet according to the present invention comprises the steps of: reheating a slab composed of 0.05-0.12 wt.% of C, 0.10-0.45 wt.% of Si, 0.9-1.6 wt.% of Mn, 0.025 wt.% or less of P, 0.015 wt.% or less of S, 0.1-0.5 wt.% of Cr, 0.01-0.04 wt.% of Ti, 0.01-0.10 wt.% of Nb, 0.1-0.5 wt.% of Ni, 0.006 wt.% or less of N, and the rest of Fe and inevitable impurities at 1000-1050°C, which is the slab reheating temperature; primarily rolling the reheated slab in an austenite recrystallization section; secondarily rolling the primarily rolled slab at 770-860°C, which is the finish rolling temperature; and cooling the secondarily rolled slab to 470-600°C at the speed of 5-12°C/sec.</p> |
