With the rapid development of science and technology, more and more industries have put forward higher requirements on the performance of steel materials, especially materials used at high temperatures. Heat-resistant steel is widely used in the manufacture of boilers, steam turbines, power machinery, industrial furnaces and parts working at high temperatures in industrial sectors such as aviation and petrochemicals. The development of heat-resistant steel is closely related to the progress of energy and power machinery. In the development of new technologies in the fields of thermal power generation, atomic energy, aerospace, aviation, petroleum and chemical industries, the performance of heat-resistant steel is the key link to its success or failure, so the importance of heat-resistant steel is increasing. At present, the biggest bottleneck in improving the energy efficiency of industries such as civil nuclear power, thermal power generation, gas power generation and chemical petroleum is the problem of metal materials, that is, the development of low-cost high-performance heat-resistant stainless steel. The development of new heat-resistant stainless steel is not only one of the effective strategies for energy conservation and emission reduction, but also can alleviate the dilemma of the gradual scarcity of nickel metal resources.

The earliest research on austenitic heat-resistant steel began in the 1930s. Krupp et al. developed stabilized austenitic steel based on 18-8 steel by reducing the C content and adding elements such as Ti, V, and Nb, obtaining fine-grained steel with dispersed carbides. The material formed Nb and Ti carbonitrides and M23C6 compounds during long-term service [1], which are the predecessors of Type 321 and Type 347 steels. Type 316 austenitic steel is obtained by adding 3% Mo to 18-8 steel. The emergence of these steels increased the corrosion resistance of the steel on the basis of the original steel [3]. In the 1970s, due to the impact of the energy crisis, various countries invested a lot of research work in the field of thermal power steel. By adjusting the stabilizing elements (Ti, V, Nb) on the basis of 18-8 austenitic steel, Tempaloy A-1 [4] steel and heat-resistant steel TP347H with fine grain structure [5] were developed. In the 1980s and 1990s, the Cr mass fraction was increased to 25%. During long-term service, the Cr element will diffuse to the surface and combine with oxygen to form an oxide layer, which plays a good anti-oxidation role. However, with the increase of Cr content, the precipitation trend of the brittle phase σ phase becomes more obvious. Therefore, the Ni content is increased at the same time to stabilize the austenite structure while inhibiting the precipitation tendency of the σ phase. Therefore, the oxidation resistance of 25-20 type austenitic heat-resistant steel is significantly improved, and it has a stable austenite structure and a long service life, which is conducive to adapting to more severe working conditions. This series of steel has high organizational stability and oxidation resistance at 800℃-1200℃, and can replace Cr20Ni25, Alloy 800, etc. and is widely used to manufacture heat-resistant industrial furnace parts.

From the current research and production level, Europe and the United States are at the leading level in the research and development and production of heat-resistant steel and user recognition. Its representative companies include Outokumpu and Sandvik in Sweden and ATI in the United States. In Asia, Japan is the main producer of heat-resistant stainless steel, but the service life of its steel grades is somewhat different from that of Sweden.

The research and development of heat-resistant stainless steel in China began at the beginning of this century. Dongfang Special Steel was one of the earliest units to start research work in this area and one of the units in China that can supply commercial materials.

Its biggest advantage is that it uses Consteel electric furnaces to smelt nickel-iron alloys. Its energy consumption is much smaller than that of traditional electric furnaces. This method breaks the existing raw material structure of pure nickel and scrap steel, and has the advantages of short smelting cycle, low raw material cost and process energy consumption. Using this method in combination with argon oxygen refining, it is possible to manufacture low-cost high-value-added products.

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