Improving erosion resistance through solution treatment of nitronic and martensitic steels for slurry erosive applications

Abstract

Erosive wear is a general phenomenon in moving underwater parts of various types of equipment and slurry transportation. Materials with high erosion resistance are recommended for such applications. Currently used martensitic steel can be replaced with nitrogen containing austenitic stainless-steel grades 21-4 N and 23-8 N due to higher erosion resistance. This paper investigates the pathway to enhance the slurry erosion resistance of nitronic steels and evaluates its feasibility to replace currently used martensitic steel for heavy slurry erosive applications. Solution treatment was observed as a potential pathway to improve slurry erosion resistance and mechanical properties of the selected steels where specimens were subjected to solution treatment at 950 °C and 1150 °C. After the solution treatment, reduced carbide volume and fine distribution in the nitrogen alloyed austenitic microstructure resulted in higher erosion resistance. Nitronic steel grades resulted in low cumulative weight loss or high erosion resistance than martensitic steel for as-received and solution-treated samples. Solution treatment resulted in a maximum reduction in cumulative weight loss for martensitic steel, 21-4 N and 23-8 N was 10 wt%, 14.2 wt%, and 18.18 wt%, respectively, at 90° impingement angle. The erosion mechanisms observed at different impingement angles were different for both nitrogen alloyed and martensitic steels. The erosion mechanism was primarily deformation at 90° impingement angle, whereas at 30° impingement angle, the mechanism was lip formation, detachment, and ploughing.