Rolling Contact Fatigue Life and Spall Propagation Characteristics of AISI M50, M50 NiL, and AISI 52100, Part III: Metallurgical Examination

Abstract

This is the third part of a three-part series that investigates the rolling contact fatigue initiation and spall propagation characteristics of three bearing materials, namely, AISI 52100, VIM-VAR M50, and VIM-VAR M50 NiL steels. Though there is substantial prior work published on the rolling contact fatigue initiation of these materials, little is known about their spall propagation characteristics after spall initiation. In Part III, 208-size, 40-mm-bore bearings are examined for changes in appearance of the microstructure as well as residual stress as a function of depth in the circumferential direction. The correlations between the experimental results from Part I and computer modeling in Part II are made.

KEY WORDS:

• Fatigue Analysis
• Rolling Element Bearings
• General
• Rolling-Contact Fatigue
• XRD

ACKNOWLEDGEMENTS

The authors would like to thank Dr. Elizabeth Cooke and the Timken Company, who supplied the M50 and M50 NiL bearings; David Gerardi and Kevin Thompson, who conducted the life testing and spall propagation testing; Winzor Morgan and Dr. David Snow of Pratt and Whitney for microstructural analysis; Tom Lachtrupp and Chris Barger of Lambda Research, who conducted the X-ray diffraction and retained austenite measurements; and Pratt and Whitney and the Air Force Research Laboratory for allowing the authors to present this work.

Review led by Mike Kotzalas