Effect of the scanning strategy on texture of grain-oriented electrical steel (Fe-4wt%Si) processed via laser powder-bed fusion and subsequent thermomechanical processing

Abstract

Abnormal grain growth is a fundamental phenomenon in the processing of grain-oriented electrical steels. The presence of inhibitors, strong texture, and reduced sheet thickness are key factors that contribute to its occurrence. In this work, a grain-oriented electrical steel (Fe-4wt%Si) was obtained using laser powder bed fusion (LPBF) additive manufacturing and subsequent thermomechanical processing. The LPBF-processed slabs were built using scanning strategies without rotation (0°) and with rotations of 45° and 90° between the layers. Subsequently, the slabs were cold rolled to 91 % reduction. Abnormal grain growth occurred during prolonged box annealing at 1200 °C, favored by the coarsening of crystalline SiO₂-based nanoparticles that acted as inhibitors of normal grain growth. The influence of the scanning strategy on the as-built texture and the magnetic properties after thermomechanical processing was investigated. Very coarse grain sizes, low porosity and reduced thickness contributed positively to the decrease in magnetic losses. The deviation of Goss grains from the ideal orientation was smaller for samples without rotation (0^o), indicating that this scanning strategy generates textures closer to the desired ones (Goss and η fiber). This strategy provided the lowest magnetic losses and the best magnetic properties among the laser scanning strategies investigated.