Austenitic heat-resistance steel with strengthened nano precipitated phase and manufacturing method thereof

Abstract

The invention discloses an austenitic heat-resistance steel with strengthened nano precipitated phase and a manufacturing method thereof, which is characterized by comprising the chemical components in percentage by mass: 0.002-0.02% of C, 24-26% of Cr, 22-24% of Ni, 0.2-0.6% of Nb+Ta, 0.15-0.35% of N, less than or equal to 2.00% of Mn, less than or equal to 0.030% of P, less than or equal to 0.030% of S, less than or equal to 0.75% of Si and the balance of Fe and unavoidable impurities. The manufacturing method comprises the following steps of: smelting, thermally machining and cold machining the components as raw materials to prepare steel pieces, and finally thermally machining, wherein the final thermal machining comprises two steps: step 1, solution treatment: heating the steel pieces to 1170-1250 DEG C, keeping the temperature for 30-60min, and then cooling the steel pieces to the room temperature by water; and step 2, annealing treatment: heating the steel pieces subjected to the solution treatment to 800-950 DEG C, keeping the temperature for 30-240min, and then cooling the steel pieces to the room temperature in air. In the invention, the steel has high-density NbCrN nanostrengthening phases uniformly distributed in crystal grains, the sizes of the high-density NbCrN nano strengthening phases range from 20nm to 60nm, the number of nano strengthening phase particles in each square micro-meter area is 5-30, and the area of M23C6 type carbides distributed on a crystal boundary is less than 20% of the area of the crystal boundary, thus the high-temperature permanent intensity is obviously improved, and the high-temperature corrosion resistance is also good.

Description

technical field [0001] The invention relates to an austenitic heat-resistant steel with nano-precipitation phase strengthening and a manufacturing method thereof, belonging to the technical field of metallurgy. Background technique [0002] Improve power generation efficiency and reduce CO 2 and other harmful gas emissions, saving resources is the future development direction of thermal power units. Improving steam parameters and developing large-capacity units are the main means to improve thermal efficiency. At present, the parameters of thermal power units in various countries in the world have developed from subcritical parameters to supercritical parameters, and even ultra-supercritical (USC) parameters. The key technology for the development of USC units is to develop heat-resistant steel materials with high thermal strength, high temperature flue gas oxidation corrosion resistance and high temperature soda medium corrosion, good weldability and processability, and r...

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Problems solved by technology

Moreover, due to the high carbon content of this heat-resistant steel, its mass fraction is between 0.04-0.10%, and a large amount of Cr-rich M is precipitated at the grain boundary during service. 23 C 6 Type carbides, leading to the formation of Cr-poor areas at the grain boundaries, increasing the tendency of high-temperature grain boundary corrosion and reducing the grain boundary strength

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