The effect of grain orientation on the initial permeability of mumetal strip

Mumetal strip samples exhibiting a high degree of preferred orientation after final heat treatment have been prepared by special processing. X-ray studies of these samples have revealed either a cube textured primary grain structure or a preferred secondary recrystallised grain structure dependent on the final heat treatment temperature. Whereas the permeability results for the cube textured samples were very poor, initial permeability values of up to 130 000 were obtained from the secondary re-crystallised material. Results for the same material showing little or no preferred orientation in the final strip are also given for comparison. The permeability results for the secondary recrystallised material were as good as or better than the randomly orientated material for a texture related to the primary cube texture matrix by a rotation of 30° about . The presence of a near cube secondary recrystallised texture resulted in a falling off in permeability giving lower results than for the random material.