Neutron Diffraction Measurements on a Large Size Roller Bearing

In common with many engineering applications the introduction of compressive surface stresses plays an important role in the performance of roller bearings. Since the introduced stress profiles depend on the treatment method and the necessary balancing tensile stresses may have unexpected consequences, it is necessary to quantify the stresses throughout the bearing. Today, most characterization of residual stresses is performed using laboratory X-ray diffraction. However, due to the limited sample size that most laboratory set-ups can handle and due to the limited penetration depth of X-rays in bearing steel, the measurements are always destructive. In this paper we present an investigation into the residual stresses in a large bearing ring of 620 mm diameter using neutron diffraction to overcome this problem. In the measurement, information was gathered from the whole cross-section of the large ring. The surface stresses were measured using laboratory X-Rays combined with successive layer removal. A comparison is made between both the neutron diffraction and X-ray diffraction measurements. INTRODUCTION Residual stresses play a major role in bearing performance as they often influence success in both manufacturing operations and during subsequent use. It can be convenient to separate stresses into those introduced by the manufacturing process and those that develop during service. However, it should not be forgotten that they are linked: the residual stresses that are created during manufacturing will influence the development of residual stresses during bearing operation [1], [2], [3], [4], [5]. 545 Copyright ©JCPDS-International Centre for Diffraction Data 2009 ISSN 1097-0002