What Are The Functions Of Heat-resistant Steel?

1. Elements formed by ferrite such as chromium, aluminum and silicon can promote the formation of dense oxide film on the metal surface at high temperature to prevent further oxidation, and are the main elements to improve the oxidation resistance and high temperature gas corrosion resistance of steel. However, excessive aluminum and silicon content will seriously deteriorate room temperature plasticity and thermoplasticity. Chromium can significantly increase the recrystallization temperature of low-alloy steel, and the strengthening effect is the best when the content is 2%.
2. Nickel and manganese can form and stabilize austenite. Nickel can increase the high temperature strength of austenitic steel and improve the carburization resistance. Although manganese can replace nickel to form austenite, it damages the oxidation resistance of heat-resistant steel.
3. Vanadium, titanium and niobium are strong carbide forming elements, which can form fine and dispersed carbides and improve the high temperature strength of steel. The combination of titanium, niobium and carbon can also prevent intergranular corrosion of austenitic steel at high temperature or after welding.
4. Carbon and nitrogen can expand and stabilize austenite, thereby improving the high-temperature strength of heat-resistant steel. When the steel contains more chromium and manganese, the solubility of nitrogen can be significantly improved, and nitrogen alloying can be used to replace the more expensive nickel.