Surface heat treatment of steel

⑴Surface quenching: the surface of the steel is rapidly heated to above the critical temperature, but the heat is quickly cooled before the heat can be transmitted to the core, so that the surface layer can be quenched in the martensite structure, and the core does not occur Phase change, which achieves the purpose of surface hardening and the core unchanged. Suitable for medium carbon steel.
⑵Chemical heat treatment: refers to the atom of chemical elements, with the help of the ability of atom diffusion at high temperature, to infiltrate the surface layer of the workpiece to change the chemical composition and structure of the surface layer of the workpiece, so as to achieve a specific surface layer of steel A heat treatment process with required organization and performance. According to the different types of infiltrating elements, chemical heat treatment can be divided into four types: carburizing, nitriding, cyaniding and metalizing.

Carburizing: Carburizing refers to the process of infiltrating carbon atoms into the surface layer of steel. It also makes the low-carbon steel workpiece have a surface layer of high-carbon steel. After quenching and low-temperature tempering, the surface layer of the workpiece has high hardness and wear resistance, while the center part of the workpiece still maintains the toughness and toughness of low-carbon steel. Plasticity.

Nitriding: Also known as nitriding, it is the process of infiltrating nitrogen atoms into the surface layer of steel. Its purpose is to improve the hardness and wear resistance of the surface layer, and to improve the fatigue strength and corrosion resistance. At present, gas nitriding is mostly used in production.

Cyanation: Also known as carbonitriding, it refers to the process of simultaneously infiltrating carbon and nitrogen atoms into steel. It makes the steel surface have the characteristics of carburizing and nitriding.

Metal infiltration: refers to the process of infiltrating the surface layer of steel with metal atoms. It alloys the surface layer of steel so that the surface of the workpiece has the characteristics of certain alloy steels and special steels, such as heat resistance, wear resistance, oxidation resistance, and corrosion resistance. Commonly used in production are aluminizing, chromizing, boronizing, siliconizing, etc.