Difference between Chemical Polishing and Electrolytic Polishing of Stainless Steel

Chemical polishing is a common surface treatment process for stainless steel. In comparison to the electrochemical polishing process, its main advantage lies in its ability to polish complex-shaped parts without the need for a DC power source and specialized fixtures, resulting in high productivity. Functionally, chemical polishing not only provides a surface with physical and chemical cleanliness but also removes the mechanical damage layer and stress layer on the stainless steel surface.

This results in a mechanically clean surface, which is beneficial for preventing localized corrosion, improving mechanical strength, and extending the service life of components.


Difference between Chemical Polishing and Electrolytic Polishing of Stainless Steel

However, practical applications pose challenges due to the diverse varieties of stainless steel. Different grades of stainless steel exhibit their own unique corrosion development patterns, making it impractical to use a single solution for chemical polishing. As a result, there are multiple data types for stainless steel chemical polishing solutions.

Stainless steel electrolytic polishing involves suspending stainless steel products on the anode and subjecting them to anodic electrolysis in an electrolytic polishing solution. Electrolytic polishing is a unique anodic process where the stainless steel product's surface undergoes two conflicting processes simultaneously: the continuous formation and dissolution of the metal surface oxide film. However, the conditions for the chemical film formed on the convex and concave surfaces of the stainless steel product to enter a passivated state are different. The concentration of metal salts in the anode area continuously increases due to anodic dissolution, forming a thick, high-resistance film on the surface of the stainless steel product.

The thickness of the thick film on the micro-convex and concave surfaces of the product varies, and the distribution of the anode micro-surface current is uneven. At locations with high current density, dissolution occurs rapidly, prioritizing the dissolution of burrs or micro-convex blocks on the product surface to achieve smoothness. In contrast, areas with lower current density exhibit slower dissolution. Due to the different current density distributions, the product surface continuously forms a film and dissolves at different rates. Simultaneously, two opposing processes occur on the anode surface: film formation and dissolution, as well as the continuous generation and dissolution of the passivation film. This results in a smooth and highly polished appearance on the surface of stainless steel products, achieving the goal of stainless steel surface polishing and refinement.


Post time: Nov-27-2023