Production Process Of Heat Resistant Steel

Heat resistant steels are alloy steels with high strength and good chemical stability at high temperatures.

Heat resistant steel includes oxidation resistant steel and thermal strength steel: oxidation resistant steel generally requires better chemical stability, but the load is lower; Thermal strength steel requires higher high temperature strength and corresponding oxidation resistance. Heat resistant steel is commonly used in the manufacture of boilers, steam turbines, power machinery, industrial furnaces and aviation, petrochemical and other industrial sectors in the high-temperature operation of parts. These components in addition to high temperature strength and resistance to high temperature oxidation corrosion, according to the use of different requirements also require enough toughness, good machinability and weldability, as well as a certain organizational stability. Heat resistant cast steel is mostly used in the cast state, but also according to the type of heat resistant steel with the corresponding heat treatment. The following is a brief introduction to the production process of heat resistant steel:

Smelting: Heat resistant steel is generally smelted in electric arc furnace or induction furnace, vacuum refining and furnace refining process are often used for high quality requirements.

Casting: some high alloy heat resistant steel is difficult to process deformation, the production of castings is not only more economical than the rolling material, but also the casting has a higher lasting strength, so the heat resistant cast steel in the heat resistant steel occupies a considerable proportion. In addition to sand casting, precision casting can also be used to obtain products with smooth surface and precise size. Centrifugal casting is often used in high temperature furnace tubes for cracking ammonia and ethylene.

Heat treatment: pearly hot steel is usually used after normalizing or tempering; The heat resistant martensitic steel is treated with quenching and tempering to stabilize the microstructure and obtain good comprehensive mechanical properties and high temperature strength.

Ferritic steel cannot be strengthened by heat treatment. In order to eliminate the internal stress caused by cold plastic deformation processing and welding, annealing treatment can be carried out at 650 ~ 830℃, after annealing, rapid cooling, in order to quickly pass 475℃ brittle temperature range; Most austenitic oxidation resistant steels are treated with high temperature solution to obtain good cold deformation. The austenitic thermo-strength steel was treated with high temperature solution first, and then aged at 60 ~ 100℃ above the service temperature to stabilize the structure and precipitate the second phase to strengthen the matrix.