Evaluation of residual stresses induced by welding by using ultrasonic method: analysis of microstructure effect

The use of the ultrasonic method for the evaluation of the residual stresses is based on the acoustoelastic effect which refers to the change in velocity of the acoustic waves propagating in a strained solid. In the case of welding, the microstructural modifications observed in the heat affected zone and the molten zone also induce variations of the velocity of the acoustic waves. The superposition of the two effects: stresses and microstructure results in over-estimating the levels of stresses. This work completed in collaboration with CETIM of Senlis is a contribution to this problem. The solution proposed consists in characterizing the acoustoelastic effect as well as the propagation velocities V0 for the different welded zones. The experimental study carried out on welded sheets with a chamfer in X on P460HLE and P265 steel, which enables to consider, that under certain conditions, the use of this method in the case of pressure equipments is possible.