Vacuum heat treatment and ordinary heat treatment

Vacuum heat treatment is a comprehensive technology combining vacuum technology with heat treatment. It refers to all and part of heat treatment process carried out in vacuum. Vacuum heat treatment can realize almost all heat treatment processes, such as quenching, annealing, tempering, carburizing, chromizing and nitriding. Gas quenching, oil quenching, nitrate quenching and water quenching can be realized in quenching process. Compared with ordinary heat treatment, vacuum heat treatment has the following advantages.

1. Non-oxidation, non-decarbonization and non-carburization have good protective effects on the interior and surface of the workpiece: oxidation makes the metal surface lose its metallic luster, increases the surface roughness and decreases the accuracy. Moreover, the oxide scale on the surface of steel is often the source of quenching soft spot and quenching cracking, and oxidation reduces the strength of steel parts and other mechanical properties. Decarburization refers to the reduction of carbon content on the surface of steel during heating. Generally speaking, the decarburization of steel is carried out simultaneously, and the decarburization layer will decrease the hardness, wear resistance and fatigue properties of steel due to oxidation, and the decarburization of high-speed steel will reduce the red hardness. Because the metal is heated in a certain vacuum, the workpiece avoids contact with oxygen. The workpiece does not oxidize and decarbonize, so it can obtain a bright surface and a better quality of heat treatment. At the same time, there will be no reduction reaction in the vacuum state, and there will be no carburization phenomenon.

2. Improve the overall mechanical properties, degassing and metal surface purification: vacuum has obvious degassing effect on liquid metals, and also has a good removal effect on dissolved gases in solid metals. Hydrogen is the most harmful gas in metals. When vacuum heating is used, hydrogen in metals and alloys can be rapidly reduced to the lowest level and hydrogen embrittlement can be eliminated, thereby improving the plasticity, toughness and fatigue strength of materials and improving the overall mechanical properties of workpieces. When metals and alloys are heated in vacuum, if the vacuum degree is lower than the decompression pressure of the corresponding oxides, the oxides will decompose, and the free oxygen formed will be discharged immediately into the vacuum chamber, which will further improve the quality of metal surface and even make the surface reach the activation state and play a purification role.

3. Small deformation of workpiece. Generally speaking, the processed workpiece is heated by thermal radiation in the furnace, the temperature difference between inside and outside is small, and the thermal stress is small, which determines that the parts processed by the vacuum heat treatment process have small deformation. At the same time, they are heated in vacuum and quenched in vacuum, which can be automatically completed, thus avoiding the workpiece’s transportation in the air in the hot state (although the salt bath treatment and atmosphere protection treatment are heated in the oxygen-insulated environment, they are still in existence). Quenching is accomplished in air or quenching medium containing oxygen molecule, which reduces artificial processing deformation. For example, the rolling wheel made of Cr12MoV material, vacuum heat treatment and salt bath treatment respectively, the deformation of vacuum heat treatment is 70% less than that of salt bath treatment, and the qualified rate of products is high.

4. It can reduce the volatility of gold-bearing elements in workpieces. Vacuum heat treatment can be heated and quenched in a controlled atmosphere, thus reducing the volatility of gold-bearing elements and ensuring the heat treatment quality of the workpiece.

5. Vacuum heat treatment furnace has high thermal efficiency, can achieve rapid heating and cooling, good stability and repeatability. Good working environment, safe operation, no pollution and pollution.

This is the advantage comparison between vacuum heat treatment and ordinary heat treatment. The above content is just a brief introduction to let you understand! If you want to know more about vacuum heat treatment, please browse our official website to learn more about vacuum heat treatment. You can also consult online or call us to contact us! We will have professional staff to give you real-time answers.