Vacuum atmosphere furnace heat treatment:
1) in the development trend of less and no oxidation heat treatment technology, the development of vacuum atmosphere furnace and vacuum heat treatment is rapid. At present, in the production of few varieties and large quantities, especially in the bright quenching, annealing, carburizing and quenching of carbon steel and general alloy structural steel parts, the application of controllable atmosphere is still the main means of carburizing and quenching. So the vacuum atmosphere furnace heat treatment is still the main component of heat treatment technology.
2) air source for atmosphere preparation. In the process of mastering and popularizing controllable atmosphere, China has come a long way in solving atmosphere problems. The earliest endothermic atmosphere generator mainly used liquefied gas, namely the higher purity propane or butane. It has been proved in recent years that China is rich in natural gas resources, which provides favorable conditions for the preparation of endothermic atmosphere from methane. Use need not be born the atmosphere of type of direct generation of furnace also is a way that nots allow to ignore.
3) heating equipment. Sealing multi - purpose furnace and multi - purpose furnace production line automation, production flexibility, applicability, so widely used
4) vacuum atmosphere furnace heat treatment process. Carburizing. High temperature carburizing is one of the developing trends of carburizing technology. Increasing carburizing temperature can significantly improve productivity and save energy. For this research can be used for above 1000 ℃ electric radiant tube material is the top priority, the development of the low pressure carburizing technology and perfect for the realization of the high temperature carburizing (1040 ℃). Steel carburizing layer depth requirements are generally conservative, and sometimes very blind. It is necessary to study the mechanical factors that determine the depth of the carburized layer and explore the possibility of reducing the carburized layer. Carbonitriding. The temperature of carburizing is lower than that of carburizing. Under seepage depth of 0.6 mm when the permeability rate of close to 930 ℃ carburizing. Abnormal microstructure is easy to occur during carbon and nitrogen carburization of steel. After quenching, the surface hardness decreases, and there are many residual austenite in the carburized layer. How to choose the proper process and give full play to the potential of carbon and nitrogen co-carburization is still a question worthy of discussion. In the past, some people advocated the high concentration of carbon and nitrogen co-infiltration, and there were also reports that the surface carbon content of steel pieces was 0.6% when carbon and nitrogen co-infiltration, which had the best comprehensive mechanical properties. It seems necessary to master these laws, to help optimize the production process. In the past and present, it has been reported that carbon and nitrogen co-infiltration was used to improve the contact fatigue strength of rolling bearings. For example, the ball and roller made of AISI52100(equivalent to GCr15) steel were changed from the previous quenching and tempering to carbonitriding, quenching, tempering, bearing failure life increased by 2.42 times. It seems that there is still a lot of work to be done to give full play to the potential of the carbonitriding process.
Vacuum heat treatment furnace
1) advantages of vacuum heat treatment. Vacuum heat treatment is a non-oxidation heat treatment technology with wide application range and controllable atmosphere. Vacuum heat treatment can not only realize no oxidation and no decarbonization of steel parts, but also realize no pollution and less distortion of workpiece. At present, it has become an irreplaceable technology in die production.
2) vacuum heat treatment process. Small distortion is an important advantage of vacuum heat treatment. According to domestic and foreign experience, the distortion of vacuum heat treatment of workpiece is only one third of that of salt bath heating and quenching. It is of great significance to popularize the vacuum heat treatment technology to study the vacuum heating modes of various materials and parts with different degrees of complexity and the distortion rules under various cooling conditions and to simulate them by computer. The uniformity of air flow during vacuum heating, atmospheric or high-pressure air quenching has a great influence on the quenching effect and quality dispersion of parts. It is of great significance to improve the structure of furnace to study the air circulation rule by means of computer simulation. Vacuum carburizing is the most possible way to achieve high temperature carburizing. However, long time heating at high temperature will make the austenitic grain size of most kinds of steel very large, for the specific steel carburizing at high temperature, reheating and quenching to study the influence of material and workpiece properties, to optimize the vacuum carburizing, cooling, heating and quenching process and equipment is very necessary. In recent years, there is an international trend of research and development of combustion type vacuum furnace using gas fuel. It is too difficult to use gas fuel for heating in vacuum furnace. Although there is a saying of energy saving, it is not necessarily an important development direction.
3) vacuum heat treatment furnace. Modern vacuum heat treatment furnace is a kind of cold wall furnace which can be heated by vacuum and then quenched in oil or in normal pressure and pressurized gas. Research and development of this type of equipment is a comprehensive, interdisciplinary, involving many fields of science and technology. The application prospect of vacuum heat treatment of mold materials is great. Most die steels are currently heated in vacuum and then cooled and quenched in gas. In order to obtain satisfactory mechanical properties on the surface and inside of the workpiece, the vacuum high-pressure gas quenching technology must be used. At present, the pressure of true air quenching in the world has increased from 0.2mpa and 0.6mpa to 1-2mpa or even 3MPa. Therefore, it is an important trend to increase the cooling gas pressure of high pressure gas quenching vacuum furnace. In addition to high-pressure gas quenching, convection heating after vacuum-pumping and then filling with high-pressure inert gas can increase the heating speed by more than twice as much as that of traditional vacuum radiation heating, thus significantly improving the heating efficiency is also one of the important directions of vacuum heating technology. To multi - functional development is also one of the trends of vacuum furnace. Oil quenching in the front chamber, atmospheric or high-pressure gas quenching in the back chamber, and vacuum heating or plasma carburizing in the middle heating chamber are typical examples. Current domestic market already had the reflection of this kind of furnace demand. Various continuous vacuum carburizing, high pressure, air cooling, quenching and tempering production lines which can meet the requirements of mass production have come out one after another. It is expected that in the near future there will be a major change in the heat treatment of automobile parts. According to the characteristics of vacuum heating easy to achieve high temperature carburizing, develop vacuum high temperature (1000 ℃ ~ 1050 ℃), carburizing, slow cooling, reheating and quenching in oil, cleaning and tempering production line should mention agenda as soon as possible.