STEEL FOR WELD CONSTRUCTION HAVING EXCELLENT HIGH-TEMPERATURE STRENGTH AND LOW-TEMPERATURE TOUGHNESS AND PROCESS FOR PRODUCING THE STEEL

摘要

Disclosed is a steel for weld construction that has excellent high-temperature strength and low-temperature toughness and can be produced at low cost. The steel for weld construction is produced by heating a steel product comprising C: 0.003 to 0.05%, Si: not more than 0.60%, Mn: 0.6 to 2.0%, P: not more than 0.020%, S: not more than 0.010%, Cr: 0.20 to 1.5%, Nb: 0.005 to 0.05%, Al: not more than 0.060%, N: 0.001 to 0.006%, and Mo as an impurity limited to not more than 0.03% with the balance consisting of iron and unavoidable impurities, the steel product having a weld cracking susceptibility composition (PCM) value, defined by PCM = C + Si/30 + Mn/20 + Cu/20 + Ni/60 + Cr/20 + Mo/15 + V/10 + 5B, of not more than 0.22%, to 1000 to 1300°C, terminating the hot rolling at a temperature of 800°C or above, and then cooling the steel product.