Comparison Of Residual Stresses Obtained By Using Neutron Diffraction and Contour Method In 80-Mm Thick Welds

Two inherently different characterization methods, non-destructive neutron diffraction and destructive contour method, have been applied for the determination of the residual stresses in an extra thick weld specimen. Two 150-mm wide, 300-mm long and 80-mm thick steel plates were joined by using flux-cored arc welding methods over 80-passes and through-thickness distribution of residual stresses were determined along the weld centerline, heat-affected zones, and base material. The deep penetration capability in neutron diffraction was achieved by using the 211 and 110 reflections with the wavelengths of 1.55 and 2.39 Å, respectively, based on the bent monochromater and wavelength selection. The gauge volumes were 5x5x8 mm³ (longitudinal) and 5x5x20 mm³ (transverse/normal), and ‘stress-free’ d_o were also considered. Both results show a good agreement and significant amounts of tensile longitudinal stresses were observed.

Keywords: Neutron diffraction; Contour method; Thick welds; Residual stress; Bragg edge