The objective of this study is mainly to elucidate the effect of stress/strain on DC/AC magnetic properties for the 4-types of soft-magnetic materials with residual pores and without. Experimentally, DC/AC magnetic measurement of PM and C/W (Cast & Wrought) ring-shape specimens were carried out in radially loaded, unloaded and annealed states in consideration of elastic and plastic strain.
The result obtained were summarized as follows:
(1) DC magnetic properties, especially maximum permeability (μm) is more sensitive to stress/strain, where degradation ratio Δμm/μm is roughly 0.4 and 0.7-0.8 (strain ε=0.005) for pure iron and magnetic alloys, respectively.
(2) In this case, PM (porous) specimens tend to be more magnetically degraded than C/W (solid) ones, presumably due to localized microstrain arised by stress concentration effect around residual pores.
(3) As for AC magnetic properties, specific permeability (μa) is degraded in almost the same way as maximum permeability (μm) and also, core loss (Pcv) is apparently reduced by stress/strain, although depending on frequency (60Hz-100kHz).
(4) DC/AC magnetic properties (μm, μa) are partially restored in the range 0.1-0.2 of degradation ratio by stress relief (unloading) at higher strain (ε=0.02), including C/W specimens.
(5) Through strain relief annealing, DC/AC magnetic properties are restored to the original value at 873K for pure iron but are not always restored to the original ones even at 1073K for magnetic alloys.
抄録全体を表示