What is Heat Resistant Steel?
Steel with oxidation resistance, sufficient high temperature strength and good heat resistance under high temperature conditions is called heat resistant steel.
Heat-resistant steel and stainless acid-resistant steel cross each other in terms of application range, and are often used in the manufacture of boilers, steam turbines, power machinery, industrial furnaces, and parts that work at high temperatures in industrial sectors such as aviation and petrochemical industries. In addition to high temperature strength and high temperature oxidation corrosion resistance, these parts also require sufficient toughness, good machinability and weldability, and certain structural stability according to different uses.
1. Classification according to high temperature performance
1. Anti-oxidation steel
Generally, steel produces brittle and porous FeO at high temperature, which has weak bonding ability with the matrix and is easy to peel off. Oxygen atoms are easy to diffuse through FeO, so that the inside of the steel continues to oxidize, eventually leading to the destruction of parts. Alloying elements such as chromium, silicon, aluminum, etc. are added to the anti-oxidation steel to form a layer of dense, high-melting oxide film (Cr2O3, SiO2, Al2O3) that firmly covers the steel surface, which can isolate the metal from the high-temperature oxidizing gas outside. , so as to avoid further oxidation.
2. Heat-resistant steel
The strength of metals at high temperatures has two characteristics: one is that the bonding force between metal atoms weakens and the strength decreases as the temperature rises; the other is that even if the stress on the metal does not exceed the elastic limit at the recrystallization temperature, it will Plastic deformation occurs slowly, and the amount of deformation increases with time, eventually leading to creep failure of the metal.
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