Effects of Copper Addition on the Precipitation of Chromium Nitrides and the Associated Pitting Corrosion Resistance of the Hyper Duplex Stainless Steels

摘要

To elucidate the effects of copper addition on the precipitation of chromium nitrides and the associated pitting corrosion of the hyper duplex stainless steels, a potentiodynamic test, a scanning electron microscope analysis and thermodynamic calculation were conducted. Copper addition to the base alloy facilitates the precipitation of chromium nitride and stabilizes it at elevated temperatures due to the increase of activity of Cr. With aging the alloy at 1293 K, copper added alloy reduces the resistance to pitting corrosion due to the precipitation of deleterious chromium nitrides compared with that of the base alloy. Experimental results are in good agreement with thermodynamic calculations of elemental activity and the driving force for the precipitation of chromium nitrides.