Using Pickling to Deburr Stainless Steel
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.”
How Does Pickling Work?
Pickling is the pre-passivation process of treating stainless steel parts with a hydrofluoric acid solution, which would remove oxide scale and heat tint while dissolving steel flecks embedded in the part. Because of EPA regulations, however, this aggressive pre-treatment is increasingly rare, and few companies still practice pickling.
Without the pickling process, the efficacy of passivation is drastically altered, and electropolishing is frequently chosen as an alternative. Electropolishing removes heat tint and oxide scale as well as embedded contaminants and surface imperfections, making metal parts more corrosion resistant than passivation can.