| 摘要 |
PROBLEM TO BE SOLVED: To provide refractory steel which has excellent high temperature strength at 650 deg.C and 700 deg.C and gas cuttability. SOLUTION: The refractory steel has a composition containing, by mass, 0.01 to 0.08% C and 0.03 to 0.15% Nb so as to satisfy the combination of C and Nb shown by coordinates within the range shown by the figure 1 in the specification, and containing 0.05 to 0.5% Si, 0.3 to 2.5% Mn, <=0.03% P, <=0.03% S, 0.03 to 0.03% Cr, 0.2 to <0.5% Mo, <=0.07 sol.Al and 0.0010 to 0.020% N, and, if required, to which one or more kinds selected from V, Ti, Cu, Ni, Ca, Mg and rare earth metals are added, and the balance substantially iron with inevitable impurities.
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