Ferrite heat resistant steel

Abstract

The invention relates to ferrite heat resistant steel which comprises the following components (wt%): 0.10-0.15% of C; 0.02-0.1% of Si; 0.2-0.7% of Mn; 10.50-11.50% of Cr; 2.50-3.00% of W; 1.5-3.50% of Co; 0.01%-2.5% of Cu; 0.10-0.20% of Mo; 0.2-0.7% of Ni; 0.20-0.30% of V; not more than 0.10% of Nb; 0.001-0.015% of B; not more than 0.01% of Zr; 0.020-0.045% of N; not more than 0.030% of P; not more than 0.030% of S; and the balance of iron and inevitable impurities. An electrode bar is cast through vacuum induction smelting; after demolding of the electrode, heat preservation is performed at 670-710 DEG C for 16-20 hours; then the electrode is annealed, slowly cooled, and discharged from a furnace; after the electrode surface is cleaned, an electroslag ingot is formed by a CaF2.Al2O3.MgO slag system; the annealing temperature of the electroslag ingot is 740-780 DEG C; heat preservation is performed for 18-24 hours; the obtained ferrite heat resistant steel has excellent room-temperature and high-temperature mechanical properties; performance of a blade prepared by the steel, such as high-temperature strength, long-time strength, high-temperature creep deformation, and the like, meets the application requirements at a steam temperature of 620 DEG C and above.

Description

technical field [0001] The invention relates to a ferritic heat-resistant steel, in particular to a steel for high-temperature blades of an ultra-supercritical steam turbine set with a service temperature above 620°C. Background technique [0002] Ultra-supercritical gas-fired power generation technology is the most advanced technology for gas-fired power generation today. Ultra-supercritical generator sets are also the development direction of today's power station equipment market. They have significant advantages such as high thermal efficiency, low pollution discharge indicators, and high degree of automation, which can significantly improve the thermal efficiency of power plant units. , reduce greenhouse gas emissions, and reduce coal consumption. [0003] Ultra-supercritical means that the steam temperature in the boiler is not lower than 593°C or the steam pressure is not lower than 31MPa. In other words, with the increase of steam temperature and steam pressure, the...

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Problems solved by technology

[0008] JP2290950A, JP58217664A, CN 1300445C, and CN101525727A are all blade steel materials that do not contain elements such as Cu, Zr, and B. The basic alloy system is similar, so elements such as Cu, B, and Zr are not added to improve the effects of aging strengthening and high-temperature strength, so it is difficult to Guarantee that the alloy has better strength and toughness in the environment of 620°C and above

[0009] Although it can be seen from Table 1 that these alloys also have good room temperature performance, the performance introduced by the Japanese patent literature is obviously higher than that of similar domestic materials, but combined with the comparison of high-temperature durability performance, the comprehensive performance of the alloy materials in the patent literature is not ideal, and the high-temperature performance is not up to the standard. practical requirements for applications up to 620°C and above

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