| 摘要 |
PROBLEM TO BE SOLVED: To produce high temperature fire resistant steel for building construction having particularly excellent fire resistance at temperature up to 850 deg.C, and to provide its production method. SOLUTION: This 850 deg.C high temperature fire resistant steel for building construction has a composition containing, by mass, 0.01 to 0.08% C, 0.2 to 2% Si, <=0.4% Mn, 0.25 to 1% Al, 0.8 to 2% Mo, 0.05 to 0.5% V, 0.02 to 0.5% Nb and >0.1 to 0.3% Ti, and the balance Fe with inevitable impurities, and in which Ac1 transformation temperature is 850 to 900 deg.C. Preferably, the content of Si is controlled to 0.2 to 1.2%, Mo to 0.8 to 1.5%, V to 0.05 to 0.2% and Nb to 0.02 to 0.2%, and one or more kinds selected from 0.1 to 2% Cu, 0.1 to 0.5% Ni, 0.1 to 1% Cr and 0.0005 to 0.01% B are further incorporated therein. In the method for producing the 850 deg.C high temperature fire resistant steel for building construction, a steel slab or a cast slab having the same steel composition is heated to >=1,150 deg.C and is subjected to hot rolling in the temperature range of <=900 deg.C at the cumulative draft of >=50% to the finished sheet thickness.
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