As for the process of high strength blackening bolt, it is a blackening treatment process at room temperature, which can be divided into the following procedures.

The first step is to clean the surface of high strength bolts.
After that, the degreasing process is started. The high strength bolt must be completely immersed in the degreasing solution. The pH value of the degreasing solution is between 12 and 14, and the soaking time of degreasing is 10 to 30 minutes. In the process of degreasing, you must do up and down shaking movement every three to five minutes. After repeated for many times, the next step can be entered. Here we need to make a special supplement. When the concentration of the solution is lower than the pH value of 12, the degreasing powder should be added. The next step is to carry out a simple water washing process. After cleaning the surface with chemicals, the pickling will be started. Acid pickling needs pickling solution to treat, and its concentration pH value is between 2 and 4. It takes five to ten minutes to complete the pickling process. After that, they have to be washed to clean the chemicals. After the completion of the project, it starts to blacken. Pour chemicals with pH value between 2.5 and 3.5 in the blackening pool to soak the high-strength bolts. The soaking time is 10-12 minutes, which can be taken out and washed. Finally, dry it with the air duct and oil it.
The process of high strength blackening bolt is relatively simple. However, it needs to be done completely and strictly according to the specified operation process.

ASTM A490 High Strength Black Oxide Hex Head Bolt

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