The reason why the color of vacuum heat treatment product is abnormal

- Apr 30, 2019-

The reason why the color of vacuum heat treatment product is abnormal


Vacuum furnace is the mainstream equipment in the heat treatment industry at present. The products processed by vacuum furnace are not only reliable in quality, but also environmentally friendly and pollution-free. Therefore, it is widely used in aerospace, weapons, electronics, automobile, machinery industry and other fields. However, it is often seen that users of vacuum furnaces post questions on the Internet about the wrong color of products produced by heat treatment of vacuum furnaces. This problem is a common problem in heat treatment production. Then, what causes it and how to solve it?


1. Detect whether there is air leakage in the vacuum furnace equipment itself

This can be determined by the pressure rise index of the vacuum furnace; Here we need to remind you that when testing the pressure rise rate, be sure to test the oven after cooling to room temperature, and can not open the furnace door after the vacuum test.


2. Check whether there is air leakage in the air inlet pipe of the vacuum furnace

Sometimes we test the vacuum furnace pressure rise rate shows normal, but there is leakage in the air inlet pipe or valve of the vacuum furnace, the pressure in the air inlet pipe is gradient, the closer to the end of the furnace is negative pressure, which is one of the reasons that the color of the product processed by the vacuum furnace is wrong.


3. Detect the purity of the inert gas into the vacuum furnace equipment

When the purity of inert gas is not enough, the mixed oxygen will lead to oxidation, decarbonization and other behaviors of the product, and then lead to product discoloration. Detection of the purity of the gas can be directly detected or through other equipment to carry out a comparative test and draw conclusions.


4. The moisture in the vacuum furnace equipment is attached to the inner wall of the vacuum furnace or the heat exchanger

This kind of moisture is difficult to exhaust through the method of the oven, when the vacuum furnace equipment does not exist in the above three problems, the product color is not processed is probably caused by this reason; At this time, we can raise the vacuum furnace equipment to high temperature, stop heating, and then feed high purity inert gas into the furnace, then start the fan circulation system, and use the high temperature and hot air in the vacuum furnace to bake out the moisture attached to the inner wall of the vacuum furnace and the heat exchanger, so as to solve this problem.


5. Why quench oil

In practice, the author found that a large part of the reason why the color is not bright after vacuum oil quenching comes from the improper choice of quenching oil.


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