LOW ALLOY HEAT RESISTANT STEEL EXCELLENT IN HIGH TEMPERATURE STRENGTH AND OXIDATION RESISTANCE AND ITS PRODUCTION

摘要

PROBLEM TO BE SOLVED: To allow steel to correspond to the increase of temp. and pressure of the steam condition while its oxidation resistance is maintained by alloying it to have a specified compsn. contg. C, Si, Mn, Cr, Mo, W, Ti, B, Nb, and the balance Fe with inevitable impurities and satisfying the total content of Mo and W to a specified range. ;SOLUTION: This steel has a compsn. composed of, by weight, 0.05 to 0.20% C, 0.05 to 0.40% Si, 0.1 to 1.0% Mn, 4.5 to 5.5% Cr 0.1 to 1.0% Mo, 0.1 to 1.0% W, 0.10 to 0.40% Ti, 0.0010 to 0.0060% B, ≤0.01 Nb, and the balance Fe with inevitable impurities. Then, the content of Mo+W is controlled to 0.2 to 1.5%. The steel whose components are controlled to the above is normalized at 1000 to 1150°C and is tempered at 700°C to the Ac1 point. In this way, the excellent steel capable of correspoinding to the increase of the temp. and pressure in vapor while its weldability and workability required as those of a steel pipe for a boiler and for chemical plant piping can be obtd.;COPYRIGHT: (C)2000,JPO