As one of the most common mechanical components in the world, roller elements are of critical importance. It is necessary for bearings and raceways to be carefully engineered and manufactured so that the machines which use them are as safe and stable as possible. The effects of residual stress and retained austenite on the performance of bearings have been commonly reported in literature. X-ray diffraction has the unique ability to provide a measurement of both retained austenite and residual stress. By knowing these data and observing how they vary with processing parameters, bearing production can be refined to provide optimal properties.
Residual stresses can be either detrimental or beneficial to many applications. This is especially true for bearings, where tensile stresses aid in the propagation of cracks and diminish fatigue life1. Bearings commonly exhibit contact fatigue. Contact fatigue results from the Hertzian stress which occurs as two rounded elements, cylinder or sphere, roll across one another. Locally, these two elements will temporarily deform, creating a contact area between the two components. This deformation and the movement of the elements as they roll produces an alternating subsurface shear stress. Over time, this will cause plastic strain to accumulate which ultimately initiates a crack2.