Correlation of ultrasonic inspection of bearing components with bearing fatigue life

One of the most important issues for bearing grade steels is the cleanliness of the steel. Impurities present in a cast steel can manifest as hard/brittle inclusions, which are detrimental to a bearing in service. An advanced ultrasonic measurement technique is developed to determine the inclusion size and density in bearing components. Using ultrasonic C-Scan, a map of the inclusions can be developed that pinpoints the worst areas in an entire cone or cup section nondestructively. A threshold is developed for determining good or bad locations so that specific-gate settings can parse those discontinuities considered to be detrimental to rolling contact performance. In addition, multiple transducer sizes and frequencies are investigated to determine an optimized scanning configuration. This protocol can then be adapted to perform quality control specific scans capable of investigating numerous parts and determining a failure rate using the rejection criteria.