Investigation on the physical origins of laser effects on anisotropic magnetic properties of GO electrical steels by means of thermal annealing

Both conventional laser surface treatments (irradiation or scribing) and recently developed ablation process performed with UltraShort Pulse Lasers (USPL) can improve magnetic properties of Grain-Oriented Electrical Steels (GOES) along their Rolling Direction (RD). While pushing the study of laser treatments further, interesting power loss reductions could also be obtained along the Transverse Direction (TD) (or other directions) of GOES using the ablation process with adapted laser patterns. To better understand the physical origins of loss reductions obtained with the USPL ablation process, the effects of a thermal annealing on GOES laser treated with various patterns are investigated. Results differ depending on the excitation direction and in connection with the applied laser treatment and pattern, which provides an original insight into the origins of the modifications of magnetic properties by laser.