What are the Reasons for the Abnormal Color of Vacuum Furnace Heat Treatment Products

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Vacuum furnace is currently the mainstream equipment in the heat treatment industry. The processed products are not only of reliable quality, but also environmentally friendly and pollution-free, without the need for three wastes treatment, and the energy consumption is significantly lower than traditional heat treatment equipment such as salt bath furnaces; therefore, they are widely used in aviation Aerospace, weapons, electronics, automobiles, machinery industry and other fields. However, I often see vacuum furnace users posting on the Internet asking about the wrong color of the products produced by the vacuum furnace heat treatment. This problem is a common problem in heat treatment production. Then, what causes it and how to solve it?

1. Check whether the vacuum furnace equipment itself leaks

This can be determined by the pressure rise rate index of the vacuum furnace; here I need to remind everyone that when testing the pressure rise rate, the furnace must be baked and then cooled to room temperature before the test, instead of opening the furnace door and then vacuuming carry out testing.

2. Check if there is any air leakage in the intake pipe of the vacuum furnace

Sometimes we test the pressure rise rate of the vacuum furnace to show that it is normal, but there is a leak in the intake pipe or valve of the vacuum furnace, and the pressure in the intake pipe has a gradient. The closer the end of the furnace body is, the more negative pressure is. This is also one of the reasons for the incorrect color of the products processed by the vacuum furnace.

3. Detect whether the purity of the inert gas passed into the vacuum furnace equipment is high or not

When the purity of the inert gas is not enough, the oxygen mixed in it will cause the product to undergo oxidation, decarburization and other behaviors, which will cause the product to change color. The purity of the detected gas can be tested directly or through comparative tests with other equipment to draw conclusions.

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

This kind of moisture is difficult to be discharged through the oven. When the vacuum furnace equipment does not have the above three problems, the color of the processed product is still incorrect. This is most of the reason; then we can remove the vacuum After the furnace equipment rises to a high temperature, stop heating, and then pass high-purity inert gas into the furnace, and then start the fan circulation system, use the high temperature and hot air in the vacuum furnace to remove the moisture attached to the inner wall of the vacuum furnace and the heat exchanger Bake it out to solve this problem.

Editing by Frank Lee

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