In the rolling process of seamless steel tubes, especially precision seamless steel tubes, the pickling process is very important to remove the oxide scale and rust on the surface. So how does pickling of seamless steel tube work?

seamless steel tube

The method of removing scale and rust on the surface of steel with an acid solution is called pickling. Iron oxides such as scale and rust (Fe3O4, Fe2O3, FeO, etc.) chemically react with the acid solution to form salts, which are dissolved in the acid solution and removed. Pickling acids include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, and mixed acids.

Common media for pickling of precision seamless steel tubes:
Sulfuric acid, nitric acid, phosphoric acid, and hydrofluoric acid. When pickling, be sure to add a pickling inhibitor to prevent the acid from corroding the metal.

Precision seamless steel tube pickling process:
There are mainly soaking pickling methods, spray pickling methods,s and acid slurry rust removal methods. Generally, the dipping and pickling method is generally used, and the spraying method can be used in mass production. Steel parts are generally pickled in 10%-20% (volume) sulfuric acid solution, and the pickling temperature is 40 °C. When the iron content in the solution exceeds 80g/L and the ferrous sulfate exceeds 215g/L, the pickling solution should be replaced. At room temperature, pickle steel with 20% to 80% (volume) hydrochloric acid solution to prevent over-corrosion and hydrogen embrittlement. Since the acid has a great corrosive effect on the metal, it is necessary to add a corrosion inhibitor. After cleaning, the metal surface becomes silver-white, and the surface is passivated to improve the corrosion resistance of stainless steel.

In order to eliminate the adsorption on the surface of the diatomite carrier and reduce the tailing of chromatographic peaks, the carrier needs to be washed with acid or alkali before use. Pickling is to soak the carrier with 6mol/L hydrochloric acid for 2 hours or with concentrated hydrochloric acid for 30 minutes, filter, wash with water until neutral, and dry. Pickling can remove impurities such as iron, aluminum, calcium, and magnesium on the surface, but cannot remove silanol groups. The acid-washed carrier is suitable for the analysis of acidic samples.

The function of precision seamless steel tube pickling:
The surface of the precision seamless steel tube is degreasing and rust-removing to prepare for the next process. In the production process, the pickling process is to remove the surface oxide scale, and then carry out lubrication treatment (carbon steel-phosphorus saponification, stainless steel-butter lime, copper-aluminum tube-oil coating), using the old process-copper plating), and then wire drawing and Deep Processing. If the steel pipe is not pickled, there may be oxides and oil stains on the surface, and the nuclear energy of the phosphating solution cannot be removed, and the quality of the phosphating will decrease.

The above is the pickling process of seamless steel tubes, I hope it will be helpful to everyone. Tianyang Steel Tube, as a seamless steel tube company from China, provide seamless steel tubes with high quality, welcome to consult and purchase.