Explanation

alloy steel with high strength and good chemical stability at high temperature. Workpieces working in high temperature environment will contact with high temperature air, steam, gas, etc., which will reduce their strength on the one hand, and affect the chemical stability of steel on the other hand. The characteristic that steel can maintain high strength without obvious deformation or fracture at high temperature is called thermal strength, while the characteristic that it can be used for a long time without scale formation or obvious corrosion at high temperature is called oxidation resistance. Therefore, heat resistant steel can generally be divided into two categories: heat strengthened steel and oxidation resistant steel (or heat resistant and non peeling steel). In order to meet the performance requirements of heat resistant steel, more than 12% CT and a small amount of alloy elements such as Al, Si can be added to improve the oxidation resistance of steel, and alloy elements such as Ni, Co, Cu, Mo, W, Cr, Al, Nb, Ti can be added to improve the thermal strength of steel. Therefore, the chemical composition of most high alloy heat resistant steel is very close to that of stainless steel, and many steel designation belong to both heat resistant steel and stainless steel (steel designation in the national standard of heat resistant steel GB/T4238-2007 are included in the standard of stainless steel and heat resistant steel GB/T20878-2007). However, the demand for high temperature strength and oxidation resistance of heat resistant steel is different from the demand for room temperature corrosion resistance of stainless steel, which requires careful consideration and different treatment in terms of steel chemical composition design and production process technology. Heat resistant steel can be divided into pearlitic heat-resistant steel, martensitic heat resistant steel, austenitic heat-resistant steel and ferritic heat-resistant steel according to its structure and characteristics. Heat resistant steel is widely used in steam boilers, steam turbines, turbines, internal combustion engines, jet engines, industrial furnace components, etc.

Classification