# An Additively Manufactured Fe-3 Si Stator for a High-Performance Electrical Motor
## 3 Results and Discussion
### AC Magnetic Properties of As-Printed Fe-3 Si Rings  
AC magnetic properties and core losses of the as-printed and annealed ring samples were measured at various combinations of excitation frequencies and magnetic induction. The losses were measured using an AMH-20K-S AC hysteresis graph and are listed in Table 3. The table shows the results for the as-printed samples, the 750 \({}^{\circ}\)C samples, and the 800 \({}^{\circ}\)C samples. The core loss results are in Watts per Pound (Watts/lb.). Freq is the excitation frequency test condition in Hertz (Hz). B\({}_{\text{m}}\) is the magnetic induction test condition in Gauss (G). Table 3 can be split into two sections. The upper section contains the three 60 Hz tests at varying induction levels. The lower level contains the data from tests at 400 Hz and above. At low frequencies, core losses in the samples were low. Core loss increases with frequency for different fields. With frequency fixed at 60 Hz, and varying induction, the higher the induction, the greater the core loss. The difference in core loss between the two annealed samples at the fixed frequency is very small across all induction values. At all combinations of frequency and induction test conditions, and under the same test conditions, the as-printed sample would show a greater loss than that of the 750 \({}^{\circ}\)C sample, which in turn would show a greater loss than that of the 800 \({}^{\circ}\)C sample. This is true except for two cases in Table 3. In the 60 Hz 15,000 Gauss case, it could just be a measurement error, as the core loss values of the three sample types are extremely close and similar to each other, and hence inaccuracies in measurement would explain this error. The same explanation can be applied to the case of the 1000 Hz 5000 Gauss results, with the core loss between the samples very similar and close to each other. Such imprecise measurements are to be expected. Under those test conditions, the results should be very similar to each other, and the test device is no longer precise enough to measure the differences between these values. Post-hydrogen annealing was carried out to remove carbon or oxide impurities and stress present on the as-printed parts, and 750 \({}^{\circ}\)C and 800 \({}^{\circ}\)C temperature annealing was chosen based on the Fe3 Si data sheet available from Carpenter Technology. The data from Table 3 suggest that annealing does have a positive impact in reducing core loss in AM FeSi. The higher the annealing temperature, the lower the core loss. In addition to boosting saturation magnetization and relative permeability, heat treatment could also reduce core losses in AM Fe3 Si. The DC and AC magnetic properties of AM Fe3 Si are combined with the previously obtained data for AM FeSi and compared with data from commercial electrical steel sheets from JFE steel, resulting in Table 4 [31]. [PERSON] et. al. investigated using several design patterns and the effect of geometry on eddy current loss [32]. In other work, [PERSON] et al. [33], [PERSON] et al. [34] and [PERSON] et al. [35] have reported laser powder bed fusion research on FeSi. Figure 7: Effect of heat treatment on the magnetic induction (**left**) and relative permeability (**right**) of the as-printed and heat-treated Fe-3 Si laminates; the Higher the annealing temperature, the higher the B or permeability values. The first thing to note is that the AM laminates could only be cut to 1.4 mm as flat rings. The EDM rings with lower thickness result in non-flat, warped rings that are unsuitable for core loss studies. In contrast, the thickest laminates in JFE Steel's electrical steel sheet catalog are 0.65 mm, with other options even thinner. This explains the higher core loss from the AM samples when compared to the commercial laminate. For all other properties, the AM laminate is similar to, or exceeds, the properties of the commercial laminate.