Affiliations: Manchester Materials Science Centre, Grosvenor Street, Manchester M1 7HS, UK | Los Alamos National Laboratory, Los Alamos, NM 87545, USA | AEA Technology plc, Culham Science Centre, Abingdon, Oxfordshire OX14 3ED, UK | FaME38 at ILL-ESRF, Institute for Materials Research, University of Salford, Salford M5 4WT, UK
Abstract: Residual stresses have been measured in a new roller-straightened railway rail and a worn ex-service rail. Synchrotron {211} lattice strain measurements at ID11 (ESRF) were used to map in-plane components of the stress tensor acting in cross-sectional rail slices. Stress maps made using laboratory X-rays and the magnetic measurement system MAPS, although coarser in detail, show similar trends. The validity of the measured data was examined using a stress balance requirement. Whilst generally true (to ± 15 MPa), stress balancing was worst (±50 MPa) in regions with significant plastic deformation, suggesting that the measured {211} lattice strain had become uncharacteristic of the bulk elastic strain. Attributable to plastic anisotropy, this is a well-established issue with diffraction-based stress determination. To complement the in-plane stress measurements, the contour method was used to map the longitudinal stress component in a similar new rail sample, this component being relieved in the slices. On the basis of this result, we show that the remaining unrelieved in-plane stresses in the rail slices are a suitable approximation of those in the original rail.
