Accelerated Testing to Investigate Corrosion Mechanisms of Carburized and Carbonitrided Martensitic Stainless Steel for Aerospace Bearings in Harsh Environments

Abstract

Carburizable martensitic stainless steels (MSSs) are attractive candidates for bearings due to their high corrosion resistance, high hardness, and high temperature performance. Wear performance in tribocorrosion applications is strongly influenced by the surrounding environment. Electrochemical testing was used to evaluate three different surface treatments on AMS 5930 steel developed for advanced gas turbine engine bearing applications: low temperature (LTT), high temperature (HTT), and carbonitrided (CN). HTT had a higher corrosion rate that increased with time, whereas LTT and CN had lower corrosion rates that were stable over time. Accelerated testing revealed that surface treatment significantly influenced how corrosion propagated: HTT was more uniform; conversely, LTT and CN showed localized attack. Degradation mechanisms developed from electrochemical methods provide rapid insight into long-term wear behavior.

Keywords:

• Corrosion
• surface modification
• carburizing
• nitriding
• ferrous alloys
• steel
• oxides
• carbides
• rolling bearings
• gas/jet turbines
• metallurgical analysis
• corrosive wear
• oxidative wear
• wear mechanism

Acknowledgements

The authors acknowledge support from Darrell Grant, U.S. Navy; Dr. Tim Piazza and Bryan McCoy, SKF Aeroengine, North America; Douglas M. Eisentraut; and Jan Clark. This article presents the work performed after the Navy project was completed. Support from the Micron School of Materials Science and Engineering is also gratefully acknowledged.