Family of B-H loops of a typical grain-oriented electrical steel (grade M4), only upper halves are shown (in 1st and 2nd quadrant, the lower parts were symmetrical).
The thick black curve shows the magnetisation curve created by joining the tips of the loops. The points marked on the vertical axis (for H = 0) have the tangential lines drawn through them (slopes) indicating reversible permeability at each such point.
The inset shows the magnetisation curve B = f (H) as the black curve, and the relative amplitude permeability as μr = f (H) as the blue curve. The permeability curve goes through a maximum at around B = 1.2 T.
For low amplitude of excitation, the permeability reduces (note the last slope changing its angle) as the initial permeability is approached.
The data was measured by S. Zurek.
permeability_cgo_m4_50hz_magnetica.png
You are permitted and indeed encouraged to use this image freely, for any legal purpose including commercial, and with any modifications (the permission is hereby given, so there is no need to ask for it explicitly again), but you MUST always give the following credits:
S. Zurek, Encyclopedia Magnetica, CC-BY-4.0
We would appreciate if you let us know of any use: info@e-magnetica.pl