Pickling Steel Basic principles
Pickling Steel Basic principles-The iron oxide scales (FeO, Fe3O4, Fe2O3) on the surface of the steel are all oxides that are insoluble in water. When they are immersed in an acid solution, these oxides react with the acid in a series of chemical reactions. reaction.
Due to the loose, porous and cracked structure of the iron oxide scale on the surface of carbon structural steel or low alloy steel, and the repeated bending of iron oxide scale along with the steel during pickling, straightening, straightening and transmission, these pores and cracks are formed. Further increase and expansion.
Therefore, while the acid solution chemically reacts with the iron oxide scale, it can also chemically react with the iron of the steel matrix through the penetration of cracks and pores.
That is to say, at the beginning of pickling, the chemical reaction between all three oxides and metal iron and acid solution is carried out at the same time. Therefore, the process of pickling includes the following three aspects:
Pickling Steel Dissolution
Various iron oxides in the iron oxide scale on the surface of the steel react chemically with the acid to form iron salts that dissolve in water and dissolve in the acid solution. When pickling with hydrochloric acid or sulfuric acid, ferrous and ferrous chlorides or sulfates that can be dissolved in the acid solution are generated, so that the iron oxide scale is removed from the surface of the strip. This effect is generally called dissolution.
Pickling Steel mechanical peeling action
In addition to various iron oxides, the iron oxide scale on the surface of the steel is also mixed with some metallic iron, and the iron oxide scale is porous, so the acid solution can pass through the pores and cracks of the iron oxide scale. The matrix iron acts, and a large amount of hydrogen is produced accordingly. The expansion pressure generated by this part of the hydrogen can peel off the iron oxide scale from the steel surface. This effect of peeling off the iron oxide scale through the expansion pressure of hydrogen generated in the reaction is generally called mechanical peeling.
Pickling Steel reduction
When metallic iron reacts with acid, hydrogen atoms are first produced. Part of the hydrogen atoms combine with each other to form hydrogen molecules, which promotes the peeling of the iron oxide scale. The other part of the hydrogen atoms reduces the oxides and salts of high-valent iron into low-valent iron oxides and low-valent iron salts that are easily soluble in acid solutions by virtue of their chemical activity and strong reducing ability.
related information:
Introduction of hot rolled coil
English 
Deutsch (Sie) 
Español 
日本語 
Français