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Advantages of double-chamber vacuum high-pressure gas quenching technology

1.Double-chamber vacuum high-pressure gas quenching and its advantages

Vacuum gas quenching (GC) can completely or partially replace oil quenching. The workpiece is clean, no oxidation, no decarburization, safe, and can be fully automated. Large flexibility, program control of the cooling process can be realized; small distortion, dimensional change can be better controlled, and the environmental load is small. High pressure air drying, no cleaning process required. The ability to handle materials and brass that may undergo surface reactions, as well as the possibility to adapt to the integration of production lines with high efficiency and low cost.

After the workpiece is heated at the austenitizing temperature, it is quenched with 0.5-2MPa (5-20bar) vacuum and high-pressure gas, which can achieve the quenching effect of static oil or high-speed circulating oil or even water. The gas quenching mechanism of the workpiece is different from the quenching mechanism of the liquid medium. The cooling in the gas is more uniform than that in the liquid, and the uniform cooling from the surface to the inner layer can be realized. Therefore, the distortion of the gas quenching is very small, and less (no) grinding can be realized. Vacuum high-pressure gas quenching uses neutral gas N₂, reducing gas H₂ and inert gas Ar, He, etc. These gases are discharged into the atmosphere without pollution, avoiding the smoke pollution caused by oil quenching, and can eliminate the lye cleaning process and discharge of oily liquids. The surface cleanliness of the treated parts is high, there is no need for subsequent cleaning and shot blasting processes, and there is no SO2 and CO emission problems, so it belongs to the clean heat treatment technology.

2.Application of vacuum low pressure carburizing + vacuum high pressure gas quenching

①In the automobile industry, vacuum high-pressure gas quenching can use single-chamber, double-chamber, and three-chamber low-pressure carburizing high-pressure gas quenching vacuum cycle furnaces and production lines composed of multi-chamber low-pressure carburizing and vacuum high-pressure gas quenching. After the synchronizer gear sleeve of the automobile transmission and the main reduction sun gear shaft of the automatic transmission are treated with this process, the thermal distortion of the parts is controlled within a very narrow range, the pass rate is greatly improved, and the dimensional accuracy of the parts is significantly improved.

② Applying an electric field in double-chamber and three-chamber furnaces can carry out low-pressure ion carburizing.

③Vacuum carburizing + vacuum high-pressure gas quenching are also applied in small modulus gears of motorcycles.

3.Double-chamber vacuum high-pressure gas quenching and air cooling system

After the workpiece is heated in a vacuum furnace or low-pressure carburizing (carbonitriding), it is gas-quenched with high-pressure N₂, He, and H₂. The cooling capacity is greatly improved by circulating the air cooling system of N₂, He, and H₂. Vacuum high-pressure gas quenching can use computer programs to control the gas flow rate, pressure and flow direction, so as to achieve the function of changing the cooling characteristics of the gas, so that the workpiece can be cooled evenly, and the martensitic transformation zone uses a small air volume to reduce the quenching distortion of the workpiece.

After carburizing, the steel is cooled in the gas more uniformly than in the liquid, so the quenching distortion is also small. Batches of alloy steel carburized parts are cooled in gas to achieve the cooling rate of oil quenching, the gas must be kept at a pressure above 1MPa, and good heat exchange (cooling) and flow circulation conditions of the gas itself are required.

The heat transfer performance of various gases is very different, hydrogen (H₂) has the best heat transfer performance, followed by helium (He), and nitrogen (N₂). Although the cooling performance of N₂ is poor, the price is the lowest, so N₂is mostly used for vacuum high-pressure gas quenching at present.

Selection of double-chamber vacuum high-pressure gas quenching furnace: The double-chamber vacuum high-pressure gas quenching furnace developed by SIMUWU company has a load capacity of 75Kg-1500Kg and an ultimate vacuum of 4*10^-3Pa/6.7*10^-4Pa. It adopts horizontal, double-chamber, and bottom-mounted formula structure. The furnace door type can be designed according to the user’s requirements, and the axial-flow high-power gas-quenching fan or the centrifugal high-power gas-quenching fan can be selected according to the processing task. It is a reliable high-quality vacuum furnace.