Ultra-supercritical thermal power generating unit steel excellent in steam corrosion oxidization resistance and high-temperature endurance property and preparing method thereof

Abstract

The invention discloses ultra-supercritical thermal power generating unit steel excellent in steam corrosion oxidization resistance and high-temperature endurance property and a preparing method thereof. The steel comprises, by mass percent, 0.08 to 0.15% of C, 0.2 to 1.0% of Si, 0.2 to 0.8% of Mn, not larger than 0.02% of P, not larger than 0.01% of S, 9.0 to 13% of Cr, 0.2 to 0.8% of Mo, 0.05 to0.32% of V, 0.02 to 0.1% of Nb, 0.002 to 0.008% of B, 0.005 to 0.3% of Al, 0.01 to 0.05% of N, not larger than 0.05% of residual elements of Ni+Zr+Pb+Sn+As, and the balance Fe and inevitable impurities. (Cr+1.5Mo+1.5Si+2Nb+2V)/(0.3Mn+30C+20N) is larger than or equal to 2.3 and smaller than or equal to 4.5, the extrapolated 100-thousand-hour endurance strength of the steel at the temperature of 620 to 650 DEG C is larger than or equal to 60 MPa, weight increment of 2000-hour oxidation corrosion at the temperature of 625 DEG C is smaller than or equal to 20 mg/cm<2>, the coefficient of thermalexpansion is 9 to 15*10<-6>K, and the steel is particularly suitable for large-scale producing of boiler tubes of an ultra-supercritical thermal power generating unit of 620 to 650 DEG C or other heat-resisting devices.

Description

technical field [0001] The invention belongs to the technical field of heat-resistant steel, and relates to a steel for ultra-supercritical thermal power units with good resistance to steam corrosion and oxidation and high-temperature durability and a preparation method thereof. Background technique [0002] At present and for a long time to come, coal power is still the main force in China's power structure, accounting for 60%, which is determined by my country's national conditions and natural resources. China has a coal power production capacity of 1 billion kilowatts. The national 2020 plan for coal power cannot exceed 1.1 billion kilowatts, and there is only 100 million kilowatts of development space. Except for projects under construction, there is basically no possibility of new projects, which limits the development of coal power. Great constraints. At present, the emission standard of coal power is already lower than the standard of natural gas combustion, and the ...

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Problems solved by technology

During operation, the 9% Cr steel mainly used on the heating surface of the superheater and reheater is T91 and T92, and the iron oxide scale produced will enter the steam turbine along with the high-pressure steam, which will damage the blades of the steam turbine and reduce the power generation efficiency. Therefore, it is necessary to develop a cost-effective steel grade that is more resistant to oxidation than T91 / 92

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