Purpose The purpose of this paper is to report on the developments in manufacturing soft magnetic materials using laser powder bed fusion (L-PBF). Design/methodology/approach Ternary soft magnetic Fe-49Co-2V powder was produced by gas atomization and used in an L-PBF machine to produce samples for material characterization. The L-PBF process parameters were optimized for the material, using a design of experiments approach. The printed samples were exposed to different heat treatment cycles to improve the magnetic properties. The magnetic properties were measured with quasi-static direct current and alternating current measurements at different frequencies and magnetic flux densities. The mechanical properties were characterized with tensile tests. Electrical resistivity of the material was measured. Findings The optimized L-PBF process parameters resulted in very low porosity. The magnetic properties improved greatly after the heat treatments because of changes in microstructure. Based on the quasi-static DC measurement results, one of the heat treatment cycles led to magnetic saturation, permeability and coercivity values comparable to a commercial Fe-Co-V alloy. The other heat treatments resulted in abnormal grain growth and poor magnetic performance. The AC measurement results showed that the magnetic losses were relatively high in the samples owing to formation of eddy currents. Research limitations/implications The influence of L-PBF process parameters on the microstructure was not investigated; hence, understanding the relationship between process parameters, heat treatments and magnetic properties would require more research. Originality/value The relationship between microstructure, chemical composition, heat treatments, resistivity and magnetic/mechanical properties of L-PBF processed Fe-Co-V alloy has not been reported previously.

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Battery electric city bus model has been created and validated with measurement results from a full-scale city bus prototype. The model utilises multi-physics modelling approach with multiple-domains from friction-tyre and transmission model to electrical drive and a simplified battery model. For the electrical drive model, four approaches to model the losses were studied. The modelled and measured motor torque, speed, current in the battery and inverter, and the bus speed were compared under two bus line driving cycles using three payloads. The simulated results were in good agreement with the experimental results; the error between the simulated and measured energy consumptions was 1.5% with the most accurate model.

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