Effect of Processing on Corrosion Behavior of Case Hardened Aerospace Bearing Steels

The reliable performance of bearing steels is critical to aerospace engine operation. Surface hardened bearing steels with major alloying elements consisting of Chromium, Cobalt, Nickel, and Molybdenum possess excellent properties for this application including resistance to multi-axial stress, high temperature allowance, excellent wear resistance and good corrosion resistance. The bearing steels are surface hardened, which alters the surface corrosion behavior compared to the bearing core. The goal of this work was to provide relevant corrosion rate data from different bearing case hardening processes to drive the development of cost efficient and better performing bearings. Electrochemical experiments were performed as a rapid assessment technique to determine the effect of different processing methods on corrosion behavior. To observe how corrosion propagates, the steels were characterized using scanning electron microscopy and surface chemical analysis. The corrosion and carbide morphology was compared with electrochemical data to gain insight on corrosion performance