Classification of high temperature non-peeling steels

Ferritic antioxidant steels are mainly chromium-based 1Cr13Si2, 1Cr18Si2 and 1Cr25Si2 steels, all of which add a small amount of silicon to improve their oxidation resistance and processability. These steels are not suitable for bearing impact loads, but have good oxidation resistance, and are suitable for manufacturing furnace components that bear little stress and work at temperatures of 800~1000 ° C, such as 1Cr13Si2, which can be used as heater hangers, nozzles, etc. 1Cr18Si2 and 1Cr25Si12 can be used as carburizing boxes.

Austenitic anti-oxidation steels include Mn18A15 chromium-nickel free steel and 3Cr18Mn12Si2N nickel-free chromium-manganese nitrogen steel, which can be used for pipes in the petroleum and chemical sectors at 850~90 and 900~1200℃ respectively, such as heating furnace tubes.

Commonly used anti-oxidation steel 3Cr18Mn12Si2N, 2Cr20Mn9Ni2Si2N, 3Cr18Ni25Si2, etc., they will form Cr2O3, SiO2, Al2O3 oxide film, improve the oxidation resistance, sulfur corrosion resistance and carburizing resistance, but also has better shear, stamping and welding properties. The addition of rare earth elements such as La and Ce in Cr steel can reduce the volatilization of Cr2O3 and form a more stable (Cr, La)2O3; It can also promote the diffusion of chromium, which is conducive to the formation of Cr2O3, and further improve the oxidation resistance. Generally, solid solution treatment is used to obtain uniform austenite structure. It can be used for parts with operating temperatures up to 1000 ° C.

The main added elements of Fe-Al-Mn heat-resistant steel are aluminum, manganese, silicon, titanium and rare earth. Among them, aluminum improves the oxidation resistance and carburizing resistance of steel, manganese expands the gamma phase zone and stabilizes austenite, rare earth elements can improve the oxidation resistance and liquid steel flow, improve the surface quality of castings, and reduce the tendency of hot cracking. Omega (C) & gt; At 0.85%, discontinuous precipitation will occur in the grain boundary of Fe-Al-Mn steel, and partial pearlite transformation will occur, resulting in embrittling of the steel. With the appropriate combination of carbon, manganese and aluminum, austenite or austenite-ferrite structure containing a small amount of δ ferrite can be obtained.