FIRE-RESISTANT STEEL EXCELLENT IN HIGH-TEMPERATURE STRENGTH, TOUGHNESS AND REHEAT EMBRITTLEMENT RESISTANCE AND PROCESS FOR PRODUCTION OF THE SAME

摘要

A fire-resistant steel excellent in high-temperature strength, toughness and reheat embrittlement resistance, which contains by mass C: 0.001 to 0.030%, Si: 0.05 to 0.50%, Mn: 0.4 to 2.0%, Nb: 0.03 to 0.50%, Ti: 0.005 to less than 0.040%, N: 0.0001 to less than 0.0050% and Al: 0.005 to 0.030% with the contents of P and S limited to 0.03% or below and 0.02% or below respectively and satisfies the relationships: C-Nb/7.74 < 0.005 and 2 < Ti/N < 12 with the balance consisting of Fe and unavoidable impurities; and a process for the production of fire-resistant steel by heating a bloom having a chemical composition as described above to 1100 to 1350°C and hot-rolling the resulting bloom with a cumulative rolling reduction of 30% or above in the temperature range of 1000°C or below.