Processing principle of vacuum heat treatment technology

What is vacuum heat treatment processing technology?
It mainly refers to a new type of heat treatment technology that combines vacuum technology with heat treatment technology. Among them, the vacuum environment of vacuum heat treatment refers to an atmosphere environment below one atmospheric pressure, including low vacuum, medium vacuum, high vacuum and ultra-high vacuum, etc. Therefore, vacuum heat treatment actually also belongs to atmosphere controlled heat treatment.
Vacuum heat treatment refers to the heat treatment process that is carried out in full or in part under a vacuum state. Vacuum heat treatment can achieve almost all the heat treatment processes that conventional heat treatment can involve, but the heat treatment quality is greatly improved.
Compared with conventional heat treatment, vacuum heat treatment processing technology can simultaneously achieve no oxidation, no decarburization, no carburization, can remove phosphorus chips on the surface of the workpiece, and has the effects of degreasing and degassing, thereby achieving the effect of surface brightening and purification.

Process principle of vacuum heat treatment processing technology
Using the phase change characteristics of metals in a vacuum state, the thermodynamics and kinetics of solid phase change do not change much in a vacuum within a range of 0.1MPa from atmospheric pressure. When formulating vacuum heat treatment process regulations, it is entirely possible to follow the principle of solid phase change under normal pressure and refer to the data of various types of organizational transformation under normal pressure. At the same time, under the effect of vacuum degassing, the physical and mechanical properties of metal materials can be improved. When heated in a vacuum state, the elements on the surface of the metal workpiece will evaporate. The vacuum degree required for metal to achieve non-oxidation heating and surface purification can achieve less oxidation and less degassing.

Characteristics of vacuum heat treatment processing technology

(1) Advantages of vacuum heat treatment processing
Vacuum heat treatment processing is a non-oxidation heat treatment technology with a wide range of applications, which is on par with controlled atmosphere. It is also one of the main signs of the advanced level of current heat treatment production technology. Vacuum heat treatment can not only achieve non-oxidation and non-decarburization of steel parts, but also achieve pollution-free production and less distortion of workpieces. Therefore, it also belongs to the category of clean and precise production technology. At present, it has become an irreplaceable advanced technology in tool and die production.
(2) Small distortion of workpieces in vacuum heat treatment process
The distortion of workpieces in vacuum heat treatment is only one-third of that in salt bath heating and quenching. It is of great significance to study the vacuum heating methods of various materials and parts of different complexity and the distortion laws under various cooling conditions, and to simulate them with computers, for the promotion of vacuum heat treatment technology. During vacuum heating, atmospheric pressure or high pressure air cooling quenching, the uniformity of air flow has a great influence on the hardening effect and quality dispersion of parts. Using computer simulation to study the air flow circulation law in the furnace is of great significance for improving the furnace structure.
(3) Use vacuum heat treatment furnace
A modern vacuum heat treatment furnace refers to a cold-wall furnace that can perform vacuum heating of components and then quench them in oil or in normal pressure and pressurized gas. Research and development of this type of equipment is a comprehensive, interdisciplinary task involving many scientific and technological fields.
The application prospects of vacuum heat treatment of tool and die materials are very large. Most tool and die steels are currently heated in a vacuum and then cooled and quenched in gas. In order to obtain satisfactory mechanical properties on the surface and inside of the workpiece, vacuum high-pressure gas quenching technology must be used. At present, the gas pressure of vacuum gas quenching has increased from 0.2MPa, 0.6MPa to 1-2MPa or even 3MPa. Therefore, the gradual increase in the cooling gas pressure of high-pressure gas quenching vacuum furnaces is an important development trend.

Vacuum Heat Treatment Furnace