Experimental investigation of lubricated surface ring crack fatigue in rolling contact

Experimental methods were developed to investigate 3-D surface ring crack fatigue failure in rolling contact. The experiments utilised HIP silicon nitride ceramic balls which contained surface ring cracks. The rolling contact tests were performed on silicon nitride/steel elements using a variety of lubricants. Silicon nitride ball surfaces were examined before the test using a dye-penetrant technique and light microscopy. The surfaces of the balls during testing, post-test and failure were examined using light microscopy. The contribution of this study is to provide understanding of the process of fatigue failure from surface ring crack and to investigate the relationship between contact stress and contact fatigue life. The experiments showed that surface ring crack fatigue failure is influenced significantly by the lubricants. A model of 3-D surface ring crack fatigue is described.