Neutron diffraction studies of laser welding residual stresses

The residual stress and microstrain distribution induced by laser beam welding of the low-alloyed C45 steel plate was investigated using high-resolution time-of-flight (TOF) neutron diffraction. The neutron diffraction experiments were performed on FSD diffractometer at the IBR-2 pulsed reactor in FLNP JINR (Dubna, Russia). The experiments have shown that the residual stress distribution across weld seam exhibit typical alternating sign character as it was observed in our previous studies. The residual stress level is varying in the range from -60 MPa to 450 MPa. At the same time, the microstrain level exhibits sharp maxima at weld seam position with maximal level of similar to 4.8.10(-3). The obtained experimental results are in good agreement with finite element method (FEM) calculations according to the STAAZ model (abbr. from German: STAAZ - Spitzentemperatur-Austenitisierungs-Abkuhlzeit). The provided numerical model validated with measured data enables to study the influence of different conditions and process parameters on the development of residual welding stresses.