Shaw Stainless offers both Electropolishing and Passivation services of stainless steel and other corrosion-resistant alloys. We have experts available to help you decide on application and budget.
Stainless steel has a protective oxide layer on the surface which provides corrosion-resistance. During the manufacturing or machining process, this layer may be removed. Electropolishing restores the corrosion-resistant properties often required in many highly-corrosive environments.
This process takes place in an electrically charged acid bath tank. It does not add material, as in a plating process, but removes material. The concept of electropolishing is to remove more of the iron from the surface and leave higher levels of chromium behind to improve the corrosion resistance of the surface. During this chemical reaction, surface stress is relieved from mechanical polishing & machining and the surface finish is improved by taking the fine highpoints off of the surface created by mechanical polishing. Also, the finish is brightened by leaving a higher chromium to iron ratio on the surface.
Shaw Stainless meets the ASTM B912 requirements for electropolishing.
Passivating stainless steel is a process that is performed on the surface of a stainless steel or alloy component. In passivation, the stainless steel spontaneously forms a surface film which makes it more passive or a chemically inactive surface and is non-reactive to air. A low corrosion rate of the metal, stainless, or alloy is the desired result of the passivation process. ASTM B912 is the standard specification for passivation of stainless steels using electropolishing. ASTM A380 / A380M-13 is the standard specification for cleaning.
Shaw Stainless meets the ASTM A380 requirements for passivation using nitric or citric acids.
Bridges, automobiles, wrought iron stair rails, and other products form a layer of rust on the surface. This is due to the fact their composition is 98% to 99% iron.
Even though your stainless steel parts can be mechanically polished to a mirror finish, the process can leave the surface layer distorted, highly stressed, and contaminated with grinding media and metallic particles from machining. This can actually lead to rust spotting or pitting in areas on the stainless steel where leftover contamination is present.
Below the part on the left is passivated only. The one on the right is electropolished. You can see theircis more reflectivity on the electropolished part on the right.
*Shaw Stainless meets the ASTM A380 requirements for passivation using nitric or citric acids.
**Shaw Stainless meets the ASTM B912 requirements for electropolishing.