Reasons for Abnormal Color of Vacuum Furnace Products
Vacuum furnace is the mainstream equipment in heat treatment industry at present. Its products are not only reliable in quality, but also environmentally friendly, pollution-free, and do not need three wastes treatment. At the same time, energy consumption is significantly lower than traditional heat treatment equipment such as salt bath furnace. Therefore, vacuum furnace is widely used in aerospace, weapons, electronics, automotive, machinery industry and other fields. However, it is often seen that users of vacuum furnaces post on the Internet asking about the wrong color of products produced by heat treatment of vacuum furnaces. This problem is a common problem in heat treatment production. So, what is the cause of this problem and how to solve it?
1. Detect whether the vacuum furnace equipment itself is leaking
This can be determined by the pressure rise rate of the vacuum furnace; here we need to remind you that when testing the pressure rise rate, we must test it after drying and then cooling to room temperature, instead of opening the door and then vacuum it.
2 Check whether there is leakage in the intake pipe of vacuum furnace
Sometimes we test the pressure rise rate of the vacuum furnace to show normal, but there is leakage in the intake pipe or valve of the vacuum furnace, and the pressure in the intake pipe is gradient. The closer to the end of the furnace body, the more negative pressure, which is also one of the reasons for the wrong color of the products processed by the vacuum furnace.
3. Detect the purity of inert gas into vacuum furnace equipment
When the purity of inert gas is not enough, the oxygen mixed into it will lead to oxidation and decarbonization of the product, which will lead to discoloration of the product. The purity of the detected gas can be directly detected or concluded through comparative tests with other equipment.
4. Moisture in the vacuum furnace equipment is attached to the inner wall of the vacuum furnace or to the heat exchanger.
This kind of humidity is difficult to be discharged by oven drying method. When the vacuum furnace equipment does not have the above three problems, the color of the product is not correct, which is mostly caused by this reason. At this time, we can raise the vacuum furnace equipment to high temperature, stop heating, then inject high purity inert gas into the furnace, and then start the fan circulation system, using the vacuum furnace. In order to solve this problem, the high temperature and hot air in the vacuum furnace will bake the moisture attached to the inner wall of the vacuum furnace and the heat exchanger.
5. Reasons for quenching oil
In practice, the author finds that a large part of the reason for the color not bright after vacuum oil quenching comes from the improper selection of quenching oil.