Domain Pattern in Silicon-Iron under Stress

This paper discusses investigations into the detailed changes in domain structure of ferromagnetic material under externally applied stress. The changes in the domain pattern of grain-oriented silicon steel with large grain size were observed and photographed while the specimen was stressed in tension.

Experiments in which the grain under observation had the {110} plane in the surface of the specimen and the $〈110〉$ direction parallel to the specimen axis, along which tension was applied, are discussed in detail. At a load of approximately 0.2 kg/${\mathrm{mm}}^2$ the original domain pattern vanishes. After a transition stage in which, over a certain range of loads, no pattern is visible at all, a new stress-induced domain pattern appears. The behavior of these patterns in horizontal and vertical magnetic fields was studied, and an interpretation of both the transition stage and the stress-induced pattern is given. In these experiments the applied stresses are all within the elastic range of the material. In the plastic range, the knowledge of the stress-induced pattern permits the detection of residual lattice strains in suitably oriented materials.