pickling

Pickling is a crucial step in steelmaking, primarily used to remove scale from hot-rolled steel before further processing, such as cold forming. Scale is composed of iron oxide crystals that form on the steel's surface during hot-rolling due to varying temperatures and oxidizing conditions.1

Acids, typically hot hydrochloric or sulfuric acid, are used to dissolve these iron oxides. Inhibitors are added to the acid to prevent the steel itself from being dissolved. For certain alloy steels, different acids like nitric acid may be required. This process can be done in continuous lines for strip steel or in batch operations for long products like bars and wire rods. Sometimes, shotblasting is used as an alternative to pickling for heavy hot-rolled products.1