Residual stress measurement of railway rails using X-ray, neutron and synchrotron radiation

This paper introduces the recent developments of techniques to measure the residual stress state of railway rails using X-rays, neutrons, and synchrotron radiation. Regarding X-rays, it explains the outline of the sin²φ method as the world standard method, and the cos α method, which is drawing attention recently. It describes that the cos α method makes it possible to measure the X-ray stress at real rails, which was difficult to date. In the neutron stress measurement method, the internal stress state of 10 mm or above, which is impossible with X-rays, can be evaluated nondestructively, and furthermore, stress measurement technique using a two-dimensional detector is being studied. Synchrotron radiation is characterized by improved position resolution, internal stress measurement, high accuracy of measurement, and mapping measurement. (A.O.)