| 摘要 |
PROBLEM TO BE SOLVED: To provide deformed bar steel for reinforcement which has the mechanical properties of a yield point of≥295 N/mm<SP>2</SP>, a tensile strength of≥440 N/mm<SP>2</SP>and an elongation of≥18%, and having excellent resistance weldability with a small amount of alloy elements, and to provide a production method therefor. SOLUTION: The deformed bar steel for reinforcement is obtained by subjecting a steel stock having a composition comprising 0.15 to 0.30% C, 0.05 to 0.5% Si, 0.40 to 1.60% Mn, <0.005% Al, 0.02 to 0.6% Cu, 0.01 to 0.3% Ni, 0.02 to 0.5% Cr and≤0.1% Mo, or further comprising one or two kinds of metals selected from≤0.040% Nb and≤0.15% V, and in which %Si+%Mn equals >0.70 to <1.70, and also, the strength index SI expressed by SI=(%C+%Si/5+%Mn/6+(%Cu+%Ni)/15+%Cr/5-%Mo/2.3+%Nb×3.5+%V×2.5)×1,000 is 300 to 650, and the balance Fe with inevitable impurities to heating, hot rolling, and cooling under specified conditions so that the structure consists of ferrite+pearlite, and the mean particle diameter of the ferrite is 7-18μm. COPYRIGHT: (C)2004,JPO
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