Production manner null of the fire-resistant steel for structure which is superior in strength at elevated temperature property after the

摘要

PURPOSE:To produce a refractory steel material for structural use excellent in high temp. strength characteristics after reheating by successively applying heating, hot rolling, and forced cooling to a steel having a specific composition in which respective contents of Mo, V, and Ti are specified under respectively specified conditions and then performing air cooling. CONSTITUTION:A steel having a composition consisting of, by weight, 0.05-0.20% C, 0.1-2.0% Si, 0.3-2.0% Mn, =0.03% P, =0.03% S, 0.1-0.4% Mo, 0.003-0.1% Ti, 0.01-0.1% V, 0.002-0.2% solAl, 0.0010-0.020% N, and the balance Fe with inevitable impurities is heated to 1000-1350 deg.C. At the time of hot-rolling this steel, reduction of area is regulated to =3% at =900 deg.C and also finishing temp. is regulated to a temp. between (Ar3-100 deg.C) and (Ar3+100 deg.C). Then forced cooling is done at 2-20 deg.C/sec cooling rate and cooling is stopped at 400-600 deg.C, followed by air cooling.