| 摘要 |
PROBLEM TO BE SOLVED: To effectively prevent the occurrence of scale defects, to reduce the surface roughness of a steel plate, and further to obtain excellent chemical convertibility and corrosion resistance even in the case of a high-tensile steel plate of >=0.5 mass% Si content. SOLUTION: In a high-tensile steel containing 0.5-2.5 mass% Si, the contents of C and Ti in particular among steel components are regulated so that they are 0.01-0.20 mass% and 0.05-0.35 mass%, respectively, and satisfy the range in inequality -1.4>=log(Ti×C)>=-1.8, and moreover, average grain size is made to <=3.0μm and also surface roughness is made to <=1.5μm arithmetic mean roughness Ra.
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