Some factors influencing the choice of vacuum furnace
Vacuum heat treatment furnace is an important equipment to realize vacuum heat treatment. The pressure in the furnace is lower than normal pressure. The atmosphere in the furnace is equivalent to a gas, so the heat treatment will not be oxidized. Vacuum treatment furnaces are widely used for vacuum tempering, aging, annealing and quenching of structural steels, non-induced steels, heat-resistant alloys, precision alloys and materials. They can also be used for vacuum degassing, brazing and sintering.
1. The vacuum furnace must be selected according to the chemical composition and heating temperature of the parts to be heat treated to meet the relationship between the equilibrium decomposition pressure of metal oxides and carbon monoxide. It is also necessary to consider certain space not to pursue high vacuum degree, which will not only lead to volatile alloying elements, but also increase the investment cost of equipment configuration.
2.The vacuum furnace is cooled by oil and gas. At present, air cooling is the main reason, because air cooling has no pollution and adverse effect on heat-treated parts. Oil - cooled surface microcarburization has effect on parts quality. After treatment, the surface of the parts does not need to be cleaned, so air quenching is usually preferred under the condition of satisfying the cooling rate. The cooling rate of air cooling is mainly affected by air pressure, flow rate, air flow pattern and distribution. When selecting the cooling rate, comprehensive consideration should be taken. Generally speaking, high pressure, high speed and rapid cooling rate are directly affected by the pressure and speed. In addition the flow of cooling water in the heat exchanger has a significant effect on the actual cooling. We realize that when the cooling water flow rate is greater than the cooling water flow rate under the same pressure and flow condition, the cooling rate is significantly faster.
3. There are some differences in the form and material of vacuum furnace heating elements in the form of heating elements. In recent years, the emergence of CFC carbon-carbon composites shows great technical advantages and the trend of replacing graphite. At the same power, the CFC material is thinner and holds less heat, which helps increase the cooling rate.
4.Functional purchasing furnaces should consider the universality of the process, that is, the temperature range of quenching and tempering should be wide. In particular, direct tempering of high temperature alloy steels after quenching is very convenient.
5.The control system is the core part of the vacuum furnace to ensure its reliability, perfection and importance. It is better to have monitoring and fault display. The recording function of imported equipment needs to be equipped with remote monitoring function to ensure the timeliness of fault treatment and reduce maintenance cost.
6. Reliability of other seal and vacuum system configurations is also an important component. In equipment modeling, we must strive for reliability on a comparative basis.