| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot-rolled steel which has a high tensile strength and a large total elongation, and excellent balance of strength and ductility. SOLUTION: (1)A chemical composition of a hot-rolled high tensile steel product consists of 0.05-0.30% C, 0.5-3% Mn, 0-3% Si, and 0-3% Al, and 0.3-3% Si(%) + soluble Al, and the remainder Fe and impurities, a structure contains austenite 15% or more in a volume ratio, and the remainder is polygonal ferrite substantially, and an average crystal grain diameter of the polygonal ferrite is 1.5-3μm. (2)One or more elements of Ti, Nb, and V can be contained. (3) When each of Si and soluble Al is 0-0.8%, and Si(%) + soluble Al(%) is 0.3-0.8%, it is also excellent in chemical conversion treatability. COPYRIGHT: (C)2004,JPO
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