The low temperature tempering temperature range is generally 150-250 degrees Celsius. The tissue obtained after low temperature tempering is cryptocrystalline martensitic + fine-grained carbide, called tempered martensitic. The microstructure of sub-eutectic steel after low temperature tempering is tempered martensitic, and the microstructure of sub-eutectic steel after low temperature tempering is tempered martensitic + carbide + residual austenite.
The purpose of low temperature tempering is to appropriately improve the toughness of quenched steel while maintaining high hardness (58-64HRC), strength and wear resistance, while significantly reducing the quenching stress and brittleness of steel
In the production of low temperature tempering is widely used in tools, measuring tools, rolling bearings, carburizing workpieces, surface quenching workpieces and so on.