Heat treatment process generally include heating, cooling, heat preservation, sometimes only three process of heating and cooling process of two. Each of these processes, completely.

Heat treatment is one of the important process. Many methods of metal heat treatment, heat is the earliest as heat source and coal, charcoal and application of liquid and gaseous fuels. The application of electric heating and easy control, and that no environmental pollution. Using these heat can be heated directly, also can pass the molten metal, and salt or floating particle indirect heating.

When heated, metal workpieces exposed to air, often happen decarburization (i.e., oxidation, steel surfaces, the carbon content of the lower) for heat treatment of surface properties are adverse effects. Therefore shall be controlled atmosphere metal are usually in the atmosphere, melting or protection and vacuum salt heat, usable also coating or packing method for protecting heating.

Heating temperature is the important parameters of heat treatment process, the choice and control of heating temperature is to ensure the quality of heat treatment. Heating temperature of metal materials and heat treatment objective vary, but generally is heated to a temperature of phase, high above. Another change requires a certain time, so as to meet the requirements of the metal surface of workpiece, also must be heating temperature is maintained at this time, make internal and external temperature consistent microstructure transformation, completely, this time as holding time. Using high energy density heating and heat treatment, heat fast, usually without holding time, and chemical treatment for a long time, often the insulation.

Cooling treatment process is indispensable steps, cooling method for process and different, main is to control the cooling speed. General annealing cooling speed is slow, the fire of cooling speed, quenching cooling speed is faster. But also because of the different kinds of different requirements, for example, empty hardened steel can use is fire cooling speed quench.

Metal heat treatment process can be divided into the whole heat treatment, surface treatment and chemical treatment three categories. According to the heating medium, heating and cooling method is different, every kinds and can be divided into a number of different heat treatment process. The same kind of metal USES different heat treatment process, can get different organizations, which have different properties. Steel is the most widely used in industry, and steel metal microstructure and most complex, therefore steel heat treatment process of various kinds.

Overall treatment is on the whole heating, cooling and with appropriate speed, to change its overall mechanics properties of metal heat treatment process. The whole steel heat annealing, are roughly fire, quenching and tempering four basic process.

Annealing is heated to a temperature of workpiece material and appropriate, according to the size of workpiece with different thermal slow cooling time, then, the purpose is to make metal internal organization or close to balance, obtain good performance and performance, or make ready for further quenching organization. Fire is the workpiece is heated to a temperature of the appropriate after cooled in the air, the effect is similar, but with the annealing, often used more fine organization to improve the cutting performance materials, and sometimes not high demand for some parts as final heat treatment.

Quenching heat preservation is the workpiece in water, oil, organic and inorganic salt solution or other such rapid cooling medium quenching. After quench hardened steel, but at the same time. In order to reduce the brittleness, steel will harden steel parts in the room below 6.5 degrees Celsius above and a proper temperature for a long time, the insulation, this process is called cooling tempering. Annealing, normalizing, quenching and tempering treatment is the "whole", one of the 4 fire quenching and tempering, often cooperate closely, be short of one cannot.

"Four fire" with heating and cooling, and different ways of different heat treatment process of evolution. In order to obtain certain strength and toughness, quenching and tempering, called the process combined. Some alloy quenching, after forming supersaturated crystallology at room temperature or the high temperature of appropriate keep for a long time, in order to improve the hardness and strength alloy or electrical magnetic etc. Such as aging treatment of metal heat treatment process.

The pressure of deformation and heat treatment process effectively and closely combined, the gain good mechanical strength and toughness with method of heat treatment deformation is called, In the atmosphere or vacuum suction in vacuum heat treatment called, it not only can make the oxidation, not after treatment, keep decarburization workpiece surface is smooth and improve the performance, still can infiltration chemical agent