Vacuum carburizing

---

Carburizing of steel is a widely used surface chemical heat treatment technology. After carburizing and quenching, a carburizing layer with high hardness and wear resistance is formed on the surface of steel, while the core maintains sufficient strength and toughness.
Though carburizing in traditional atmosphere is widely used at present, many problems are exposed
1. Internal oxidation of workpiece, non equine structure is difficult to avoid
2. Large exhaust emission
3. Long carburizing period
4. Workpiece is easy to oxidize and decarbonize, etc

Compared with traditional atmosphere carburizing, vacuum carburization reduces the treatment cost and reduces environmental pollution, and achieves excellent surface state and uniformity of carburized layer. Vacuum carburizing also has advantages of small quenching deformation, high carburizing efficiency and avoiding grain boundary oxidation.

With the comprehensive implementation of national energy conservation and emission reduction policies and environmental protection policies, further guide the heat treatment industry to develop in the direction of “less oxidation, less cutting”, clean, green and pollution-free vacuum carburizing technology will gradually replace the traditional gas carburizing, and reduce the consumption of national resources and energy.

Vacuum carburizing technology: high purity C2H2 (purity ≥ 99.9%) is often used as carburizing gas, because carburizing and subsequent heat treatment are carried out in vacuum environment, and the carburizing medium does not contain “oxygen”, so as to avoid the shortcomings of carburizing layer oxidation and decarburization which are easy to occur in traditional atmosphere carburizing. In addition to the advantages of vacuum heat treatment, it also has the following advantages:

1. Good surface quality: the vacuum carburized surface does not oxidize or decarburize, and keeps the metal color; does not produce internal oxidation (black structure), which helps to improve the fatigue strength of parts; greatly improves the reliability and service life of products.

2. Small workpiece deformation: when the vacuum carburizing workpiece is heated, the heating speed is continuously controllable, which can reduce the deformation trend of the internal and external temperature difference of the workpiece; after carburizing, the quenching method is vacuum quenching, which can greatly reduce the quenching deformation of the workpiece; reduce the processing amount in the later stage and save the processing cost.

3. The depth of carburizing layer is more uniform: after the workpiece is heated to uniform temperature, carburizing gas is introduced to ensure the synchronization of the initial carburizing point of large and small workpieces, which is the basis of uniform carburizing layer. Vacuum can purify the surface of the workpiece, which is conducive to the adsorption of carbon atoms by the workpiece. Because of the good uniformity of carburizing depth, shallow carburizing is easier to control.

4. The surface carbon content is easy to control: the surface carbon content of vacuum carburizing does not need to be controlled by carbon potential, but can be precisely controlled by controlling carburizing pressure and carburizing gas flow.

5. Wide range of carburizing temperature: from low-temperature carburizing to the highest carburizing temperature can reach 1050 ℃, which can greatly save the process time for deep carburizing. It is more beneficial to complete the carburizing process of special steel grades.

6. Stable carburizing quality: after the process parameters are set, the whole carburizing process is controlled by a microcomputer and the process parameters are recorded. The control system can accurately control the carburizing process, and the heat treatment workpiece has good repeatability and stable quality.

7. High production efficiency: high temperature carburizing can greatly shorten the production cycle. Effectively save time and energy cost, improve production efficiency.

Wide range of application: vacuum carburizing can achieve the parts with blind holes, deep holes and slits, or the parts with poor or even difficult carburizing effect such as stainless steel, silicon steel, etc. vacuum carburizing can obtain good carburizing layer.

Learn more: Vacuum carburizing furnace