A Reverse Time of Flight Approach to Neutron Diffraction Residual Stress Investigation on a UNI-FE510D Steel Welded Plate

Abstract

The Reverse Time of Flight (RTOF) technique, used at the Fourier Diffractometer HRFD of the IBR-2 reactor of the FLNP in Dubna, Russia, is exploited in the neutron diffraction analysis of the residual stress (RS) state in a welded plate of ferritic steel UNI-Fe510D (Italian code). A constant uniaxial stress along the axis transverse to the weld adds to the weld stresses in regions far from the weld pool (WP). Stresses very near to the yield strength have been found. A through-thickness scan shows that stresses are constant as a function of depth. Results are in good agreement with previous work and fulfil the stress balance. The unstrained lattice parameter was found to vary slightly from the parent material to the WP. Good agreement was also obtained with results from the steady state sources of Risø, Denmark (TAS8 diffractometer) and from Řež, near Prague, Czech Republic (TKSN-400 spectrometer). In particular, in spite of the different instrumental concept and measurement method, the through thickness and across weld stress behaviour is common to all the three sets of data.