Residual strain measurement for arc welding and localised high-pressure rolling using resistance strain gauges and neutron diffraction

Neutron diffraction and foil resistance strain gauges have been used to study the state of residual stress introduced by localised high-pressure rolling of structural steel plates, and compare it to that caused by gas metal arc welding. Rolling creates a region in which the residual stress state is highly compressive in the rolling direction. Furthermore, this region is sharply defined, making it potentially very suitable for cancelling out the tensile residual stresses caused by welding. It is also demonstrated that non-destructive strain measurements made during the welding and rolling processes can be used to indicate residual elastic strain and stress, and that this method shows good agreement with conventional neutron diffraction measurements. Determination of residual stresses in this way requires consideration of the effect of curvature on the values of strain measured at the surface of the object.