In the production process of electric heating tubes, blackening treatment is sometimes used. The heat treatment is a process of heat treatment of metal objects such as stainless steel. After the treatment, there will be an oxide film on the surface to achieve the purpose of anti-corrosion and anti-rust, which will be improved after the heat treatment. The wear resistance of the surface of the heating pipe increases the hardness of the surface without affecting the components inside the electric heating pipe.
Under the normal working conditions, the easiest way to blacken the surface of the electric heating tube is as follows:
1. First clean the surface of the metal tube and keep it clean;
2, the second is the surface of the degreasing treatment, this process can completely place the metal tube in the degreasing liquid. The pH of the degreased liquid is preferably around 13, the time is not less than half an hour, and it is washed with water after degreasing;
3. Next, pickling can be carried out. The pH value of the pickling solution is about 3, the treatment time is not longer than 10 minutes, and the water is washed after pickling;
4, blackening treatment: pool liquid concentration PH value 2-4, processing time 10 minutes up and down, be sure to clean after blackening;
5. Finally, dry and oil.