Application of Vacuum Carburizing

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Vacuum carburizing refers to a process of gas carburizing under the condition of less than one atmospheric pressure. In 1950, the United States began to study vacuum carburizing and applied for a patent in 1960. In 1972, Hayes CO. published the vacuum carburizing technology. And successively developed various types of vacuum carburizing furnaces, which are now widely used in industrial production.

SIMUWU is a manufacturer specializing in process equipment including vacuum carburizing furnaces. Based on its experience in vacuum carburizing, this paper briefly introduces the industrial application of vacuum carburizing process.

1. Gears

The application of vacuum carburizing treatment to gears is one of the most effective treatments. In the past gas carburizing, due to the large difference in the wall thickness of the gear, the carburizing depth was inevitably uneven, especially the carburizing depth at the top and bottom of the tooth, which had a very bad influence on the fatigue strength of the gear. There is a heating problem to reach the carburizing temperature. During gas carburizing, the treated parts are loaded into the heated furnace. According to the mass effect, due to the different heating times at different parts of the wall thickness of the treated parts, when the heat is not uniform, Carburizing begins, so the difference in wall thickness results in a difference in carburizing depth. In this regard, in the vacuum carburizing process, after the parts are installed in the furnace, they are heated from room temperature, and the heating rate is adjusted according to the shape of the processed parts, and has nothing to do with the wall thickness. Uniform and uniform carburized layer. For example, a certain bevel gear material is SCM-22, the maximum outer diameter is 750 mm, the weight is 300 kg, the effective carburizing depth is 1.7 mm, and the total time for carburizing and quenching is about 10 hours, which is about the past gas carburizing treatment half the time. The surface of the part has a metallic luster, and the deformation is smaller than that of the gas carburizing treatment in the past, reducing the workload of subsequent machining.

2. Deep carburized parts

In the past, the maximum depth that can be achieved by carburizing is about 3.5 mm, but when the vacuum carburizing process is used, the carburizing can reach 7 mm. Since the surface carbon potential is about 1.7%C during high temperature carburizing at 1040℃, which is nearly double that of gas carburizing in the past, such a large concentration gradient accelerates the diffusion of carbon to the core of the part. A carburized layer with a depth of 7 mm can be obtained by carburizing with a vacuum carburizing process for about 11 hours.

3. Recarburization of decarburized materials

The parts whose surface has been decarburized in the heat treatment process or the forging and sintering process can be recarburized with this process under the condition that the surface carbon potential is controlled. In addition to being effective for carbon steel, recarburization treatment is also effective for die steel and high-speed steel with a decarburized layer of 0.02-0.1 mm.

4. Carburizing treatment of stainless steel

Since this process is a high-temperature carburizing treatment, various stainless steels, including austenitic stainless steels that were difficult to carburize in the past, can be easily carburized. We believe that this treatment process is most effective for the 13Cr series stainless steel that requires wear resistance, and it is expected to be quite effective. The current test results show that the hardness is above Hv800, and the carburizing depth can also reach 2~3 mm. In addition, it can be used as a substitute for SUS-44OC, and the use of stainless steel with a high carbon surface should be considered as a substitute steel.

The RVN vacuum carburizing furnace produced by SIMUWU is a high-quality product for this kind of brazing process. Good temperature control accuracy and temperature control uniformity ensure the effective progress of the vacuum brazing process. With more than ten years of sales and manufacturing experience, it is exported to developed regions in Europe, America and Asia. It is a widely acclaimed vacuum furnace product.