| 摘要 |
Provided is a ultrahigh strength steel for a welded structure having superior toughness in a weld heat-affected zone (HAZ) comprising: by wt %, carbon (C): 0.05% to 0.15%, silicon (Si): 0.1% to 0.6%, manganese (Mn): 1.5% to 3.0%, nickel (Ni): 0.1% to 0.5%, molybdenum (Mo): 0.1% to 0.5%, chromium (Cr): 0.1% to 1.0%, copper (Cu): 0.1% to 0.4%, titanium (Ti): 0.005% to 0.1%, niobium (Nb): 0.01% to 0.03%, boron (B): 0.0003% to 0.004%, aluminum (Al): 0.005% to 0.1%, nitrogen (N): 0.001% to 0.006%, phosphorus (P): 0.015% or less, sulfur (S): 0.015% or less, iron (Fe) as a residual component thereof, and inevitable impurities. |
| 主权项 |
1. A ultrahigh strength steel for a welded structure having superior toughness in a weld heat-affected zone (HAZ) comprising:
by wt %, carbon (C): 0.05% to 0.15%, silicon (Si): 0.1% to 0.6%, manganese (Mn): 1.5% to 3.0%, nickel (Ni): 0.1% to 0.5%, molybdenum (Mo): 0.1% to 0.5%, chromium (Cr): 0.1% to 1.0%, copper (Cu): 0.1% to 0.4%, titanium (Ti): 0.005% to 0.1%, niobium (Nb): 0.01% to 0.03%, boron (B): 0.0003% to 0.004%, aluminum (Al): 0.005% to 0.1%, nitrogen (N): 0.001% to 0.006%, phosphorus (P): 0.015% or less, sulfur (S): 0.015% or less, iron (Fe) as a residual component thereof, and inevitable impurities, wherein the Ti and N component contents satisfy Formula 1 below, the N and B component contents satisfy Formula 2 below, and the Mn, Cr, Mo, Ni, and Nb component contents satisfy Formula 3 below; and a microstructure including, by area fraction, acicular ferrite in an amount of 30% to 40% and bainite in an amount of 60% to 70%,
3.5≦Ti/N≦7.0 [Formula 1]1.5≦N/B≦4.0 [Formula 2]4.0 2≦Mn+Cr+Mo+Ni+3Nb≦7.0 [Formula 3] wherein in the Formulas 1 to 3, respective component units are wt %. |
