To produce a steel for structural purpose having excellent corrosion resistance and fire resistance and excellent in brittle fracture resistance even under high speed deformation caused by a big earthquake or the like by providing the steel with a specified compsn. in which Cu, Cr, Mo, Nb or the like effective for the improvement of atmosphere corrosion resistance and fire resistance are added and the contents of S and O are stictly limited and specifying the value of reduction of area under static loading conditions by a notched spacimen whose stress concentration factor is specified.
This steel has a compsn. contg., by weight, 0.05 to 0.2% C, 0.01 to 0.7% Si, 0.5 to 2% Mn, 0.001 to 0.1% sol.Al, 0.2 to 1% Cu, 0.3 to 15 Cr, 0.1 to 0.7% Mo, <0.005% S and 0.003% O, furthermore contg. one or more kinds among 0.005 to 0.1% Nb, 0.01 to 0.2% V and 0.003 to 0.1% Ti, and the balance Fe. The steel has ≥30% value of reduction of area under static loading conditions in a tensile test using a specimen having a notch whose stress concentration factor is regulated to ≥5. Furthermore, as the steel components, one or more kinds of ≥1% Ni and 0.0005 to 0.005% B may be contained as well.
Suzuki, Shinichi
Kobayashi, Yasuo
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