Functional characterization of L-PBF produced FeSi2.9 Soft Magnetic Material

Electromagnetic shielding properties of LPBF produced Fe2.9wt.%Si alloy

“…The magnetic characterization based on the SF index allowed to demonstrate that even starting from an elementary shield geometry inspired by a relé application, the LPBF process allowed to build ferromagnetic shields with similar performances of those fabricated with a standard approach that consists in folding a 1 mm sheet Zn-coated mild steel. The present work demonstrated that as-built shields should undergo a further annealing heat treatment to match the adequate shielding performances, as also demonstrated in a previous work [28] for other magnetic properties, like permeability or specific iron losses. This is because, as demonstrated in reference [28], after the heat treatment there is an increase in the permeability of the material so that the magnetic field lines tend to be bounded easily in the piece.…”

“…The present work demonstrated that as-built shields should undergo a further annealing heat treatment to match the adequate shielding performances, as also demonstrated in a previous work [28] for other magnetic properties, like permeability or specific iron losses. This is because, as demonstrated in reference [28], after the heat treatment there is an increase in the permeability of the material so that the magnetic field lines tend to be bounded easily in the piece. Once heat treatment is performed, the microstructure changes from a columnar-dominated grain fashion to a mixture of large and coarse grains still stretched along the build direction and residues of columnar grains from the as-built condition.…”

“…Instead, the heat treated condition outperformed the other two in each of the measurement point considered, especially in point 1, which is the deepest and therefore the closest to the shield. This type of heat treatment can increase the electrical and magnetic properties, particularly the permeability of the piece due to the microstructural change, as reported in [28], thus favoring an increase in the shielding properties.…”

“…Toroid samples were produced to test the electromagnetic properties in as-built and heat treated conditions. The so called 'O-ring test' in which the B-H curve for the material before and after the heat-treatment was evaluated at 10, 20, 30, 40, 50, 60, 100, 500, 1000 Hz [28].…”

“…The highest maturity level in terms of LPBF processability has been reached with electrical steel compositions [8]. So far, several works have been published with Fe2.9wt.%Si [28][29][30], Fe3wt.%Si [20,22,24,31], Fe3.7wt.%Si [32,33], Fe6.5wt.%Si [20,23,31,34,35], Fe6.7wt.%Si [36], Fe6.9wt.%Si [37][38][39][40],…”