The Electropolishing of Chromium and Its Alloys

A technique for electropolishing chromium and chromium-based alloys has been devised. The polishing baths contain orthophosphoric acid, sulphuric acid and water, or orthophosphoric acid alone. Conditions are given for obtaining rapid smoothing, polishing and electroetching of the surface for metallographic examination. The probable mechanisms of electropolishing, and of anodic passivity on chromium in the polishing bath, are discussed.