The pickling of titanium alloy tube surface includes: pickling, pickling and acid dip.

Acid dip: The metal is soaked in acid for a long time to remove thicker oxides. For example, hot rolled steel plate before cold rolling acid leaching to remove the scale and oxide skin produced in the rolling process.

Pickling: Used for descaling of metal equipment, and also for removing metal oxides without prolonged acid soaking. Such as electroplating, coating, phosphating before the removal of oxide and rust, titanium surface oxide removal.

Acid stain: In the process of processing and short-term storage of metal parts, a thin oxide layer may be generated on the surface, then only need to wipe with a small concentration of acid solution on the metal surface to remove the oxide layer. Removal of discolored parts and oxide skin from metal surfaces, as by welding or hot working.

Principle of pickling

Action of dissolution

Various acid-soluble oxides in the oxide layer on the metal surface react chemically with the acid to form water-soluble metal salts that dissolve in the acid solution so as to remove the skin of the oxide layer. This action is generally called dissolution.

Mechanical stripping action

In addition to various oxides, the oxide layer on the surface of the metal is also mixed with some metal elements, and the oxide layer has a porous property, acid solution through the pores and cracks of the oxide layer and the metal elements or matrix elements in the oxide layer, and the corresponding generation of H2. The expansion pressure created by this H2 gas can peel the oxide layer from the metal surface. This action of stripping off the oxide layer by the expansion pressure of the reaction to produce H2 is commonly referred to as mechanical stripping.

Effect of reduction

When a metal interacts with an acid, it first produces H2 atoms. Some H2 atoms combine with each other to form H2 molecules, which promotes the stripping of the oxide layer. The other part of the hydroproons rely on its chemical activity and strong reducing ability to reduce the high metal oxides and high metal salts into low metal oxides and low salt soluble in acid solution.