What is the corrosion resistance of AL-6XN stainless steel?

 　　1. Overall corrosion, AL-6XN stainless steel has better corrosion resistance in some acid media than 316L and 904L, and is superior to or equivalent to C-276 alloy. In H2SO4 with high Cl - concentration, especially in hydrochloric acid, the corrosion resistance strength is only better than 904L, but lower than another 7% Mo type super austenitic stainless steel 654SMO. In HCl, the corrosion resistance of AL-6XN steel is still lower than 654SMO, but better than that of super duplex steel 2507, 904L, 304, and 316.

　　2. Pitting corrosion: Under certain conditions, the pitting corrosion resistance of AL-6XN steel is superior to 316L, 317L, and 904L, but similar to G3 alloy but lower than alloy 625. Due to the influence of welding, the post weld pitting resistance of AL-6XN decreases. However, compared with grades 316L, 317L, and 904L with lower molybdenum content, AL-6XN with high molybdenum content and nitrogen content is still the best.

　　3. Crack corrosion, the decrease in corrosion resistance (pitting corrosion resistance, crack corrosion resistance) of AL-6XN steel occurs before the decrease in toughness of this steel, especially at lower temperatures; The corrosion resistance of this steel significantly decreases at around 700 ℃, and this trend is suppressed when the temperature is ≥ 927 ℃. The critical crack temperature of this steel is as high as 43 ℃, which is only lower than the nickel based corrosion-resistant alloy C-276. This indicates that AL-6XN steel has good resistance to crevice corrosion. AL-6XN has the best resistance to pitting and crevice corrosion when the PRE value reaches 47.6.

　　4. Intergranular corrosion. As AL-6XN steel generally only contains about 0.02% C, there is little chromium carbide precipitation. However, when hot working, heat treatment and welding processes are improper, there is still a risk of intergranular corrosion due to the precipitation of intermetallic phase and Cr ₂ N along the grain boundary.

　　5. Stress corrosion, under certain conditions, when the temperature is less than 121 ℃, this steel is immune to stress corrosion.



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