Effects of precipitate and crystal orientation on the magnetic properties of non-oriented FeSi steel components upon aging process

F Citrawati and TH Priyanto and PA Paristiawan and MY Hasbi and MA Prasetyo and SA Chandra and J Syarif, SCIENTIFIC REPORTS, 15, 36870 (2025).

DOI: 10.1038/s41598-025-20824-x

Three non-oriented FeSi steel samples with varying carbon contents (0.41 wt% C, 0.18 wt% C, and 0.05 wt% C) were subjected to thermal aging to investigate the combined effects of carbon content and preferred crystal orientation on magnetic performance. In the initial state, the 0.18FeSi sample exhibited the steepest hysteresis curve and the lowest average coercivity (Hc approximate to 115 A/m), attributed to its high cumulative density of <100> components, particularly hkl<100> (eta- fiber) component. Saturation magnetization (Ms) varied across directions and compositions, with the 0.05FeSi sample consistently showing the lowest Ms, likely influenced by variations in its alloying elements. After aging at 180 degrees C for 20 days, the 0.41FeSi sample exhibited flattened hysteresis curves and a significant increase in Hc, while the 0.18FeSi sample showed an Hc increase but retained a steep curve. The 0.41FeSi sample formed a high density of similar to 2 mu m iron-carbide precipitates, whereas the 0.18FeSi sample had fewer, smaller precipitates (similar to 1.6 mu m); no precipitates were observed in the 0.05FeSi sample. The precipitate-matrix orientation relationships likely follow the Baker-Nutting or Pitsch model, promoting nucleation along the 110 and 100 planes. Despite having the highest density of 100 and hkl<100> fibers after aging, the 0.18FeSi sample exhibited increased Hc while maintaining a steep hysteresis curve. These findings indicate that while favorable texture improves magnetic performance, the presence of precipitates-depending on their density and size-can partially degrade coercivity and overall magnetic behavior after aging.

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