Study of Residual Stresses in a Stainless Steel Tube with a Welded Ferritic Cover by Neutron Diffraction

Shape welding of a ferritic steel layer on an austenitic steel tube is used to build compressive stresses on its outer surface and as a result, suppress stress corrosion. Investigations of residual stresses in such bi-layer tubes are important for developing optimal welding techniques. The neutron diffraction method is used to analyse the welded region on the tube. To this end, strain components in the tangential, radial and axial directions are measured across the weld on the HRFD Fourier diffractometer in FLNP and the ENGIN stress-diffractometer in ISIS. The results of stress calculation from the experimental data are compared to the data obtained by the destructive turning out technique and the theoretical predictions using the finite element method.