Method in vacuum heat treatment

In the processing and production of vacuum heat treatment, the surface of the processed product often has problems in "coloring". Obtaining a bright, non-colored product processing effect is a common goal pursued by manufacturers and users of vacuum furnaces. So what is the reason that affects the brightness? What factors are related to it? How can the product be bright? This is another issue that is of great concern to frontline technicians and workers.
The coloring is caused by oxidation, and the different colors are related to the temperature generated and the thickness of the oxide film. Quenching in oil at 1200 °C will also cause surface carburization and melting. If the vacuum is too high, it will cause the elements to volatilize and bond; these will damage the surface brightness.
In order to obtain a better bright surface, the measures to be taken into consideration and considered in production practice are as follows:
1 First, the technical specifications of the vacuum furnace should conform to the national standards.
2 Process processing should be reasonable and correct.
3 The vacuum furnace cannot be contaminated.
4 If necessary, wash the furnace with high purity inert gas before entering the furnace and before discharging.
5 Before going through a reasonable oven.
6 When using cooling, use an inert gas (or a certain proportion of strong reducing gas).
It is easier to obtain a bright surface in a vacuum furnace because it is not easy to obtain a protective atmosphere with a dew point of -74 ° C, and the cost is high; and obtaining a vacuum atmosphere equivalent to -74 ° C dew point, and the same pure impurity content is easy. In the processing of vacuum heat treatment, the relative difficulty of stainless steel, titanium alloy and high temperature alloy is relatively large. Tool steel to prevent element evaporation, pressure (vacuum degree) should be controlled at 70 ~ 130Pa. It is easier for carbon steel and alloy structural steel to obtain a bright surface.

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