Though passivation can improve the corrosion resistance of stainless steel parts, manufacturing leaves behind many imperfections that passivation does not eliminate. The process does not, for example, remove heat tint or oxide scale created by welding and heat treating. In the past, this has been addressed by a supplementary chemical treatment known as “pickling.”
Pickling is a pre-passivation process of treating stainless steel parts with an acid solution, typically hydrochloric or sulfuric acid, which can remove oxide scale and heat tint while dissolving steel flecks embedded in the part. But pickling is a very imprecise process, with many drawbacks, including strict EPA regulations around its use. It is also very difficult to create consistent results as the acid solution degrades with age and the amount of surface material removed can vary greatly.
Over the years, electropolishing has emerged as a preferred alternative and a one-stop method for removing surface imperfections, removing a microscopically precise layer of surface material and leaving parts stronger, ultraclean, and resistant to both corrosion and pathogens. Unlike pickling, electropolishing is effective at improving the finish on a wide variety of metals, alloys and specialty alloys.
