1.There are four polishing methods for dual-phase steel flange: manual, mechanical, chemical and electrochemical.The corrosion resistance and decoration of the flange can be improved by polishing. Phosphoric acid and chromic anhydride are still used in the existing electric polishing solution of stainless steel. During polishing and cleaning, some chromium and phosphorus will be discharged into wastewater, causing pollution to the environment.

2.The surface of the dual-phase steel flange will form a passivation film, while the oxide film begins to dissolve.Because the surface microstructure of dual-phase steel flange is inconsistent, the slightly convex part of the surface is preferentially dissolved, and the dissolution rate is higher than that of the concave part. Film dissolution and formation are almost at the same time, but their speeds are different.As a result, the surface roughness of dual-phase steel flanges is reduced and a smooth, shiny surface is obtained.

3.Through polishing can fill the surface pores, scratches and other surface defects, and then improve the resistance to fatigue.