Residual Stress Measurements in a Three-Bead Slot Weld in a 20 mm Carbon Steel Plate

Residual stresses have been measured by different techniques in a 3-bead slot weld in a carbon steel plate. Neutron diffraction has been applied at two different facilities, the High Flux Reactor of the Joint Research Centre in the Netherlands and the new research reactor FRM-II in Germany. Furthermore, measurements by surface hole drilling and by the contour method have been obtained by the Open University in the UK. The neutron measurements have been executed with different settings of the instruments and employing different crystallographic reflection planes of the bcc-lattice of the low-alloy steel. The results were found to be in remarkably good agreement in the base material, away from the fusion zone. Closer to and within the fusion zone, differences of significant magnitude between the measurements have been found. It has to be noted that the differences found were only in the absolute stress values, and not in the general trends of the stress distributions. The comparison between neutron diffraction and contour data is limited to common measurement locations and directions, e.g. through thickness measurements at the weld centre line and the start and stop ends, in the welding transverse direction, which is the direction of the contour measurements. A reasonable qualitative agreement has been obtained, but no exact quantitative agreement. The paper makes an attempt to explain the similarities and the differences between the measurements, and provides an outlook to additional work done in this context within the NeT European Network, also with a view to establishing methods to obtain better agreement of the stresses found in measurements at different facilities and/or by different methods.