After the passivation layer of stainless steel is formed, it has good acid resistance, which is one of the important reasons for stainless steel to obtain excellent corrosion resistance. The passivation layer refers to a dense, stable and firmly attached oxide layer formed on the surface of stainless steel.
The chromium element in stainless steel reacts with oxygen in the air to form a thin and uniform dense oxide film (passivation layer). This oxide film protects the stainless steel from corrosion by preventing further attack by oxygen, water and other media. In addition, the passivation layer has the ability to self-heal, and when the passivation layer is slightly damaged, it can be regenerated through oxidation reactions to continue to perform its protective function.
In common acidic media, the passivation layer can effectively block the erosion of acids and protect the internal structure of stainless steel from corrosion. Acidic media include sulfuric acid, hydrochloric acid, nitric acid, etc. However, it should be noted that the resistance of the passivation layer to different acidic media is also different, and different stainless steel materials and different acidic concentrations and temperatures have different effects on the corrosion of the passivation layer. When selecting stainless steel materials and using acidic media for treatment, the specific working environment and operating conditions should be taken into account to ensure that stainless steel can well withstand acidic media.
It should be noted that the passivation layer is not absolutely acid-resistant, and if the acidic medium is too corrosive, the concentration is too high, or the temperature is too high, it may cause a certain degree of erosion to the stainless steel. Therefore, when using acidic medium to treat stainless steel, attention should be paid to controlling the concentration, temperature and action time of the acidic medium, and timely cleaning and treatment to protect the passivation layer of stainless steel. If there is a high demand for the acid resistance of stainless steel, it is recommended to choose a more corrosion-resistant stainless steel material, such as AISI 316, etc., according to the specific situation.
All in all, the stainless steel passivation layer has good acid resistance after formation, which can resist the erosion of general acidic media. However, according to the specific working environment and working conditions, select suitable stainless steel materials, and pay attention to the concentration, temperature and action time of the acidic medium to ensure that the acid resistance of stainless steel is long-lasting and effective.