Tuomas Riipinen, Sini Metsä-Kortelainen, Tomi Lindroos, Janne Sami Keränen, Aino Manninen and Jenni Pippuri-Mäkeläinen
The purpose of this paper is to report on the developments in manufacturing soft magnetic materials using laser powder bed fusion (L-PBF).
Abstract
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.
Details
Keywords
Anouar Belahcen, Emad Dlala and Jenni Pippuri
The purpose of this paper is to implement and test a 1D eddy‐current model for laminated iron core of electrical machines and investigate the possibility of incorporating it in a…
Abstract
Purpose
The purpose of this paper is to implement and test a 1D eddy‐current model for laminated iron core of electrical machines and investigate the possibility of incorporating it in a 2D FE analysis.
Design/methodology/approach
The 1D eddy‐current model of laminated core is extended to handle rotating‐field problems and coupling between the x‐ and y‐components of the magnetic field. Explicit coupling terms are introduced in the Jacobean matrix to ensure convergence and time efficiency. The procedure is computationally tested for both the case where there is no feedback to the 2D FE and the case where the results of the eddy‐current model were fed‐back to the 2D analysis.
Findings
The coupling terms ensured fast and robust convergence. The incorporation of the eddy‐current model in the 2D FE analysis is possible, provided some under‐relaxation is used to ensure the convergence of the overall 1D‐2D procedure.
Research limitations/implications
The method has been computationally tested with 2D like procedure corresponding to a 2D model with only one element. The behaviour of the model in actual 2D computation presents some problems related to the convergence of the overall procedure and they have been dealt with in another publication.
Originality/value
The paper is of practical value for designers of electrical machines. On one hand, the model can be used a posteriori to estimate eddy‐current losses in iron stacks, and on the other hand it can be incorporated into 2D FE analysis including the losses in the field solution and enhancing its power and energy balance.