It was observed some years ago by the authors that some differences in magnetic properties exist between heat treated specimens cut from forged and from unforged ingot; the initial permeability of forged specimen was found to be 2_??_3 folds and coercive force 1/2_??_1/3 as compared to unforged one. In this report the effects of forging on magnetic properties was studied experimentally on permalloy, and the following conclusions were drawn.
(1) Cast alloy has more or less impurity films on crystal surfaces which make the allloy non-uniform magnetic, accompanying self demagnetization.
By forging impurity films are destroyed and result following changes in magnetic properties.
(a) Increase of permeability.
(b) Increase of residual magnetism.
(2) Ordinary east specimen having microscopic or sub-microscopically inhomogeneous parts here and there causes some internal stresses.
By forging the homogenization is progressed and reduces internal stresses, by which the following changes in magnetic properties take place.
(c) Increase of permeability.
(d) Decrease of coercive force.