CORROSION-RESISTANT STEEL FOR CHIMNEY/FLUE USE IN NATURAL GAS-FIRED OR LIQUEFIED PETROLEUM GAS-FIRED PLANTS
Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants, containing C: 0.005% to 0.030%, Si: 0.18% to 0.50%, Mn: 1.50% to less than 3.00, P: 0.030% or less, S: 0.0050% or less, Cr: 4.0% to 9.0%, Al: 0.20% to 1.50%, and N: 0.020% or less and able to prevent advanced pitting or other localized corrosion and the resultant hole formation and rust aerial dispersal is provided.
1 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants, excellent in rust resistance, rust adhesion, and localized corrosion resistance, characterized by containing, by mass %,
C: 0.005% to 0.030%,
Si: 0.18% to 0.50%,
Mn: 1.50% to less than 3.00,
P: 0.030% or less,
S: 0.0050% or less,
Cr: 4.0% to 9.0%,
Al: 0.20% to 1.50%,
N: 0.020% or less, and
having a balance of Fe and unavoidable impurities.
2 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants as set forth in claim 1 , characterized by further containing, by mass %,
Cu: 0.05% to 0.50% and
Ni: 0.05% to 0.50%.
3 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants as set forth in claim 1 or 2 , characterized by further containing, by mass %, one or more of
Mo: 0.01% to 0.20%,
V: 0.005% to 0.050%,
Nb: 0.005% to 0.050%, and
Ti: 0.005% to less than 0.030%.
4 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants as set forth in claim 1 or 2 , characterized by further containing, by mass %, one or more of
Ca: 0.0005% to 0.010%,
Mg: 0.0005% to 0.010%, and
REM: 0.001% to 0.010%.
5 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants as set forth in claim 1 or 2 , characterized in that it has on its surface a 5 to 100 μm thick inorganic zinc-rich paint layer containing metal zinc in an amount of 30 mass % or more.
6 . Corrosion-resistant steel for chimney/flue use in natural gas-fired or liquefied petroleum gas-fired plants as set forth in claim 5 , characterized in that it has, on an outer surface side of said inorganic zinc-rich paint layer, a 20 to 400 μm thick silicone-based resin layer.