High strength and high induction Co27–Fe–Co0.23 soft magnetic alloy for forge application

Abstract

In magnetic bearing or flywheel technologies, there is a demand for high induction soft magnetic alloys for forged components rotating at high speed (50 000–80 000 rpm). Hiperco® Alloy 27 (Co27–Fe) is ductile and has high magnetic saturation (24 kG) but with low yield stress (35–55 ksi). This work reports a carbon strengthened Co27Fe–C0.23 alloy with high yield stress (75–85 ksi), high induction (B=20 and 21 kG at H=100 and 150 Oe, respectively), and good ductility (1 in. elongation=21%). Postforge annealing is critical to achieve desired combination of high magnetic induction, high yield stress, and good ductility.