Posco Co., Ltd

Jeong-Eun Kim

Tae-Jin Song

Chang-Sik Choi

Hyeon-Seok Hwang

Sung-Il Kim

Je-Woong Lee

Chung-Won Kim

Jung-Ki Kim

Cho-Rong Hong

Doo-Jin Paik

Seul-Ki Park

Provided is a method of manufacturing a hot rolled steel sheet having excellent formability and fatigue properties, including: preparing a slab including, by weight %, 0.3 to 0.8% of carbon C, 13 to 25% of manganese (Mn), 0.1 to 1.0% of vanadium (V), 0.005 to 2.0% of silicon (Si), 0.01 to 2.5% of aluminum (Al), 0.03% or less of phosphorus (P), 0.03% or less of sulfur (S), 0.04% or less (excluding 0%) of nitrogen (N), and a remainder of iron (Fe) and inevitable impurities; heating the slab to 1050 to 1250° C.; finish rolling, the slab heated in the heating, at a temperature of not lower than a recrystallization temperature of a region having an average V concentration and not higher than a recrystallization temperature of a region having twice the average V concentration, to obtain a hot rolled steel sheet; and coiling the hot-rolled steel sheet at 50 to 700° C.

Hot rolled steel sheet having excellent formability and fatigue properties and manufacturing method therefor

Provided is a hot rolled steel sheet having excellent formability and fatigue properties comprising, in percentage by weight: 0.3-0.8% of C; 13-25% of Mn; 0.1-1.0% of V; 0.005-2.0% of Si; 0.01-2.5% of Al; 0.03% or less of P; 0.03% or less of S; 0.04% or less (excluding 0%) of N; and the balance being Fe and inevitable impurities, wherein, when viewed in a cross section in the thickness direction, the hot rolled steel sheet comprises, by area fraction, 20-70% of a non-recrystallized structure and 30-80% of a recrystallized structure.

Provided is a steel sheet having excellent image clarity after painting, including: carbon (C): 0.001% to 0.03%, silicon (Si): 0.001% to 0.35%, manganese (Mn): 0.05% to 2.2%, phosphorus (P): 0.003% to 0.1%, sulfur (S): 0.001% or 0.025%, aluminum (Al): 0.01% to 0.1%, nitrogen (N): 0.001% to 0.007%, and a remainder of iron (Fe) and inevitable impurities. The microstructure of the steel sheet mainly is ferrite phases. An R-cube texture of a surface layer of the steel sheet is 5% or less by area %.

Steel sheet having excellent image clarity after painting

Growing community of inventors

Gwangyang-si, South Korea

Jeong-Eun Kim