Additive manufacturing of Fe-3.5 wt.-%Si electrical steel via laser powder bed fusion and subsequent thermomechanical processing

A novel additive manufacturing approach is proposed to produce an electrical steel (Fe-3.5%Si) by laser powder bed fusion (LPBF) followed by conventional thermomechanical processing. The aim of this proof-of-concept study is to develop a new processing route for grain-oriented electrical steels from LPBF-processed plates with strong texture and SiO₂ nanoparticles followed by cold rolling and long-term annealing to trigger abnormal grain growth. The slabs were processed with two different scanning strategies; e.g., with (90R) and without 90° rotation (0R) between layers aiming at intensifying the as-built textures near-Goss and/or cube components. The as-built slabs were cold rolled to 83% reduction and annealed for subsequent monitoring of primary recrystallization and abnormal grain growth. Goss or near-Goss nuclei were identified for both strategies after cold rolling. Abnormal grain growth occurred more intensely in samples with a 90° rotation between layers. Goss-oriented grains are bounded by high-angle boundaries with peak misorientations of 50° in 90R and 37.5° in 0R strategy. Porosity in 0R is three times higher than in 90R, while the total fraction of CSL boundaries is similar for both strategies (about 6%). Boundary mobility seems to be higher in 90R, which explains easier grain boundary depinning from oxide nanoparticles than in 0R strategy. In comparison with grain-oriented commercial products, increased total magnetic losses can be explained by thickness effects, porosity and deviation from ideal Goss orientation.