We are often confused by the term of Descaling ,Pickling ,Passivation, but they are different process of surface treatment .It is very important to be clear about the difference between these surface treatment processes as applied in stainless steel production.
Descaling is the removal of a visible oxide scale from the surface. This oxide scale is usually dark grey.
Pickling is the removal of a thin layer of metal from the surface of stainless steel .Mixtures of nitric and hydrofluoric acid are common used for pickling stainless steel .
Passivation usually occurs naturally on the surface of stainless steels, but it may be need assist from oxidising acid treatments, unlike pickling, no metal is removed from the surface during acid assisted passivation .
