Welding the steel is less deformed

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PROBLEM TO BE SOLVED : To provide a steel sheet capable of inexpensvely and securely suppressing welding deformation in a fillet welding. ŽSOLUTION : The steel sheet having reduced welding deformation has a chemical composition containing, by mass, 0.02 to 0.25% C, 0.01 to 0.7% Si, 0.3 to 2% Mn, ≤0.05% P, ≤0.008% S, 1 to 2.5% Cr, ≤0.05% Mo, 0.005 to 0.1% Nb, 0.003 to 0.1% Al and ≤0.01% N, and the balance Fe with impurities, and has a metallic structure composed of a ferritic structure of 10 to 60% and a bainitic structure and/or a martensitic structure of 40 to 90%, and in which the average grain size of the ferritic structure is ≤30 μm and the ratio between the hardness of the bainitic structure and/or martensitic structure and the hardness of the ferritic structure is ≥1.5. The steel sheet may further comprise one or more kinds selected from Ti, Cu, Ni, V, B, Zr, Ca, Mg and rare earth metals. ŽCOPYRIGHT : (C)2010, JPO&INPIT Ž