Product heat treated by vacuum furnace reason for the abnormal color

Vacuum furnace is the mainstream equipment of heat treatment industry at present, the products it processed do not oxidize, do not decarbonize, the products after treatment still maintain the surface bright and original luster, the surface is usually not available, the workpiece without deformation, high wear resistance and service life, the workpiece has degreasing degassing effect; Pollution-free, pollution-free, high degree of automation, so it is widely used in aerospace, weapons, electronics, automobiles, machinery industry and other fields. But people often consult the vacuum furnace heat treatment out of the color of the product wrong reason, this is a common problem in the heat treatment production, so, what is the cause of the cause how to solve?

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

Sometimes the pressure rise rate of the vacuum furnace is normal when we test it, but there is air leakage in the air inlet pipe or valve of the vacuum furnace, and the pressure in the air inlet pipe is gradient. The closer to the furnace body, the more negative pressure there is, which is one of the reasons that the products processed by the vacuum furnace have the wrong color

2. Check whether the vacuum furnace equipment itself has air leakage

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

3. 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 very difficult to be discharged through the oven, when the vacuum furnace equipment does not exist the above three problems, the product color is still wrong is mostly caused by this reason; At this time, we can raise the vacuum furnace equipment to a high temperature, stop heating, and into the furnace into the high purity of inert gas, and then start the fan circulation system, using the high temperature and hot air in the vacuum furnace attached to the wall of the vacuum furnace and heat exchanger above the drying out of the moisture, so as to solve this problem.

4. Test whether the purity of the inert gas is high or not

When the purity of the inert gas is not enough, the oxygen will lead to oxidation and decarburization of the product, and then lead to discoloration of the product. The purity of the gas can be determined by direct detection or by comparison with other equipment.