China Metal Heat Treatment Workshop

The heat treatment process is a technical process that controls the internal structure and mechanical properties of metal materials by heating, heat preservation and cooling. According to different process requirements, common heat treatment methods include annealing, quenching, tempering, normalizing, carburizing, etc., the purpose is to improve the hardness, strength, toughness, wear resistance and other properties of the metal to meet the needs of specific use conditions. By precisely controlling the heating temperature, cooling rate and heat preservation time, heat treatment can adjust the microstructure of the metal, optimize the mechanical properties of castings and forgings, and improve the overall performance and service life of the parts material.

The choice of heat treatment method depends on the material, size, purpose and required performance of the castings and forgings. By reasonably selecting different heat treatment processes, the hardness, strength, wear resistance, plasticity and other properties of the metal can be improved in a targeted manner, thereby meeting the requirements of various mechanical parts in actual use.

Annealing is the process of slowly cooling a metal after heating it to a certain temperature and keeping it for a certain period of time.

Annealing methods can be divided into ordinary annealing, spheroidizing annealing, stress relief annealing, etc. according to different cooling methods.

Quenching is to heat the metal to a certain temperature, usually above its critical point, and then cool it quickly (usually with water, oil or air). This process can significantly increase the hardness of the metal surface.

The quenched metal usually becomes brittle due to excessive internal stress, so tempering is required to release the internal stress and reduce brittleness.

Tempering is the process of reheating the quenched metal to a certain temperature, keeping it for a period of time, and then slowly cooling it.

The temperature and time of tempering will directly affect the properties of the metal, and it is usually divided into low-temperature tempering, medium-temperature tempering and high-temperature tempering.

Normalizing is to heat the metal to a temperature higher than the annealing temperature but lower than its melting point, and then cool it in the air.

Compared with annealing, normalizing has a faster cooling rate and can obtain a more uniform structure.

Carburizing is heating low carbon steel to high temperature (usually 900-950°C) and treating it in a carbon-containing atmosphere, so that carbon atoms penetrate into the metal surface, thereby increasing the surface hardness and wear resistance. Carburizing is usually used for high-load parts such as gears and bearings.

Nitriding is heating steel parts to medium-low temperature (usually 500-550°C) and placing them in a nitrogen-containing atmosphere (such as ammonia) to allow nitrogen atoms to penetrate into the metal surface.

Nitriding is similar to carburizing, but nitriding is carried out at a lower temperature, does not require subsequent quenching treatment, and can obtain a more uniform and dense surface hardened layer.

Induction hardening is to heat the metal surface through the magnetic field generated by high-frequency current, quickly heat it to the quenching temperature, and then cool it with water or oil to achieve hardening.

Induction hardening is often used for mechanical parts, such as gears, bearings, etc., which require high surface hardness and good internal toughness.

Surface hardening is to locally heat the metal surface through different heating methods (such as laser, flame, etc.), and then quickly cool it to achieve the effect of surface hardening.

Martempering is a process in which the workpiece is heated to a relatively high temperature, then quickly cooled to a relatively low temperature and maintained for a certain period of time during the quenching process, and finally cooled to room temperature.