To provide fire-resistant steel having excellent fire resistance which exhibits high strength even at high temperatures and excellent weldability.
The steel has a composition containing, by mass, >0.03 to 0.15% C, 0.05 to 1.0% Si, 0.1 to 2.0% Mn, 0.02 to 0.1% Al, 0.6 to 1.0% Cu, 0.05 to <0.40% Mo, 0.005 to 0.1% Ti, 0.0003 to 0.003% B and 0.001 to 0.005% Ca. Those elements are also allowed to satisfy the following inequalities (1) and (2). Further, in the case of a steel in which the content of Cu is >1.0 to 2.0%, the steel is allowed to satisfy the following inequality (2): 1.5≤([Cu]+5000×[Mo]×[B])...(1), and (5000×[Mo]×[B])≤2.4...(2); [wherein, [Cu] is the content (mass%) of Cu, [Mo] is the content (mass%) of Mo, and [B] is the content (mass%) of B].
HATANO HITOSHI
HATAKE HIDEO
MAKII KOICHI
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