![]() The following table summarizes the results of testing in boiling salt solutions of 26% NaCl (sodium chloride), 33% LiCl (lithium chloride), and 42% MgCl2 (magnesium chloride). The relative resistance of a stainless steel to chloride SCC is often quantified by the use of standard boiling salt solutions. The duplex stainless steel with their dual austenite/ferrite microstructures has a resistance that is in between that of the austenite and ferrite grades. ![]() The ferritic family of stainless steels, which includes grades such as type 430 and 444 is very resistant to chloride SCC. ![]() Austenitic grades with relatively high nickel and molybdenum contents such as alloy 20, 904L, and the 6% molybdenum super austenitic grades have substantially better chloride SCC resistance. Therefore, standard grades such as 304/304L and 316/316L are very susceptible to this mode of attack. The most susceptible austenitic grades have nickel contents in the range of 8 to 10 wt%. The resistance of austenitic stainless steels to SCC is related to the nickel content of the steel. The austenitic family of stainless steels is the most susceptible. The relative resistance to chloride SCC is dependant on the stainless steel family. Although no stainless steel grade is totally immune to chloride SCC, the relative resistance of stainless steels varies substantially. The most common environmental exposure condition responsible for SCC of stainless steels is the presence of chlorides. This mode of attack is termed stress corrosion cracking (SCC). The combination of tensile stress and a specific corrosive environment can crack stainless steels. ![]()
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