Nickel alloys, especially the nickel (Ni)-chromium (Cr)-molybdenum (Mo) family, offer excellent resistance to hydrochloric acid. The objective of this paper is to study the corrosion performance of various Ni based alloys in high concentrations of HCl acids below the boiling point.
In this work, the corrosion resistance of nickel-based alloys C- 276 (UNS N10276), C-22 (UNS N06022), C-2000 (UNS N06200), Hybrid-BC1 (UNS N10362) and B-3 (UNS N10675) in mill annealed condition were studied in highly concentrated (25-37wt.%) HCl solutions. Based on the available data, an attempt was made to draw iso-corrosion diagrams 10 mpy (0.25mm/y) and 20 mpy (0.5 mm/y) for selected alloys in the range 25 to 35 wt.% HCl. Additionally, the corrosion rates of the above-mentioned alloys subjected to heat treatment (760°C/15 min/air cool) were studied via immersion and electrochemical linear polarization resistance (LPR) methods and compared to the corrosion rates obtained in mill annealed condition.
This study shows that heat treated alloys show relatively much higher corrosion rates when exposed to higher concentrated HCl solutions at higher temperatures.
Divi, S., Spiller, D., “Corrosion Performance of Nickel Based Alloys in Highly Concentrated Hydrochloric Acid,” Proceedings of the NACE Corrosion 2017 (NACE-2017-9639), New Orleans, LA, March 26 – 30, 2017.