| 摘要 |
A fire resistant high strength rolled steel material superior in fire resistance and toughness used for a structural member of a building etc. containing, by mass%,
C: 0.005% to less than 0.04%,
Mn: 0.8 to 1.7%,
Si: 0.05 to less than 0.4%,
Nb: 0.02 to 1%,
Ti: 0.005 to 0.02%,
N: 0.005% or less,
B: 0.0003 to 0.003%, and
Al: 0.005% to 0.03%,
and a balance of Fe and unavoidable impurities, and having the ratio Ti/N of 2 to 8, the value C-Nb/7.74 of 0.02% or less, and having the ratio of the 0.2% yield strength at 600°C to the yield strength at room temperature of 0.50 or more. |
