What do you know about pitting corrosion of metals and the pitting equivalent prEN?
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Pitting, also known as pitting corrosion, is a type of corrosion that occurs in a very small area on the metal surface and penetrates deep into the metal. Pitting is generally small in diameter but deep. The ratio of the maximum depth of the pit to the average corrosion depth of the metal is called the pitting coefficient. A higher pitting coefficient indicates a more severe degree of pitting. Pitting Equivalence Number: Also known as the pitting resistance equivalent, it is referred to in English as Pitting Resistance Equivalent Number, or PREN for short. It is a calculation method based on the mass fraction of certain elements in a metal, and its value is often used as a means to assess the resistance of metals to pitting corrosion. In different versions of the data, there are several formulas for PREN, but generally, this is the most commonly used formula: PREN = Cr% + 3.3 * Mo% + 16 * N%. Pitting equivalent of various metal materials; chloride ion concentration tolerance corresponding to the pitting equivalent
With the previous agreements, there seems to be an issue with the last table. The PREN value for 316L is around 23.6, while that for 304 is around 18.5. According to this table, 316L can be used in environments with a chloride content of less than 200, but is 304 completely unsuitable in such conditions? There’s still a temperature gauge at room temperature that hasn’t been sent
Austenitic stainless steel is exactly like that; it is most vulnerable to chloride corrosion