Corrosion in nitric acid

The corrosion resistance of nickel-based and iron-nickel-based corrosion resistant alloys in nitric acid depends on the chromium content of the alloy. The higher the chromium content in the alloy, the better the corrosion resistance. G-30 alloy and 690 alloy exhibit the best corrosion resistance due to the high chromium content of the alloy. The molybdenum in the alloy is detrimental to its corrosion resistance in nitric acid, but no significant effect of molybdenum content below 7%.

98% of concentrated nitric acid has a strong oxidizing property. The passivation film of chromium alone cannot guarantee the strong nitric acid corrosion resistance of the alloy. The high Si austenitic stainless steel containing 4% Si has been successfully applied in the concentrated nitric acid environment. For high-silicon nickel-base alloys, only single-phase Ni-Si solid solution alloys have good corrosion resistance in 60% to 99% HN03 below 80 degrees Celsius, whereas in dilute HN03, the corrosion rate is quite high, and therefore in concentrated-nitrogen sales. In the corrosive environment, inexpensive high-Si stainless steels tend to be used.

Post time: Mar-27-2018


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