Purpose of pickling and passivation of austenitic stainless steel:
In engineering, pickling and passivation treatment is usually carried out to make the potential of corrosion of stainless steel play a greater role. Generally, thorough cleaning, including alkaline cleaning and pickling, and then passivation with oxidant, can ensure the integrity and stability of passivation film.
One of the purposes of pickling is to create favorable conditions for passivation treatment and ensure the formation of high-quality passivation film. Because the average thickness of stainless steel surface is 10 microns through pickling One layer of surface is corroded, and the chemical activity of acid solution makes the dissolution rate of defective parts higher than that of other parts on the surface, so pickling can make the whole surface tend to be even and balanced, and some hidden dangers that are easy to cause corrosion are removed.
But more importantly, through pickling and passivation, the oxides of iron and iron are dissolved preferentially than those of chromium and chromium, and the chromium poor layer is removed, resulting in chromium on the surface of stainless steel The composition and structure of this chromium rich passivation film can improve the corrosion resistance of stainless steel. The cleaning, pickling and passivation of stainless steel surface can not only maximize the corrosion resistance, but also prevent product pollution and obtain beautiful appearance.