Patent ID: 8702875

Claim:
A steel sheet comprising, in % by weight, C: 0.03-0.1%; Si: 0.005-0.105%; Mn: 1.0-3.0%; P: 0.005-0.04%; S: 0.003% or less; N: 0.003-0.008%; Al: 0.05-0.4%; V: 0.005-0.05%; additional components consisting of Mo and Cr, wherein concentrations of the additional components satisfies the inequality 10<50*[Mo %]+100*[Cr %]<30; and a balance of Fe and unavoidable impurities, wherein a microstructure of the steel sheet includes at least two phases comprising, in an area ratio of cross-sectional structure, 70% or more ferrite phase having a Vickers hardness Hv of 120-250 and 10% or more martensite phase having a Vickers hardness Hv of 321-555; and wherein the concentrations of the additional components which satisfies the inequality 10<50*[Mo %]+100[Cr %]<30, simultaneously increases the strength and obviates wettability deteriation of the steel sheet.