Most titanium alloy sheet,titanium alloy rod,titanium alloy tube requires surface treatment during and after heat treatment, so as to remove the oxide scale and various pollutants on the metal surface and reduce the activity of the bare metal surface. Surface treatment is also required before and during the coating process of titanium and its alloy surface halogen coating protective layer and various functional coatings. The coating is applied to improve the performance of the metal surface, for example, Prevent corrosion, oxidation and wear.
The pickling conditions of titanium and its alloys depend on the type (characteristics) of oxide layer and existing reaction layer, and the type of this layer is affected by the increase of temperature in high temperature heating process and processing process (such as forging, casting, welding, etc.). Only a thin oxide layer is generated at a low processing temperature or a high temperature heating temperature below 600X. An oxygen rich diffusion zone is formed near an oxide layer under high temperature conditions, and the oxygen rich diffusion layer must also be removed by pickling. Various methods for removing oxide scale can be adopted: mechanical method for removing thick oxide layer and hard surface layer, method for removing oxide scale in molten salt bath and method for removing oxide scale by acid pickling in acid solution.
In many cases, a combination of several methods can be used, for example, the combination of mechanical scale removal and acid pickling, Or the scale removal method combining salt bath and acid pickling ^ special methods shall be adopted in case of oxide layer and diffusion layer formed at high temperature, but most of the oxide layer formed when the high temperature is heated to 600X: can be dissolved by general acid pickling.
