DOMAIN-STRUCTURES IN SILICON-IRON IN THE STRESS TRANSITION STAGE

Static domain structures in grain-oriented 3% silicon-iron strip have been studied using the Kerr magnetooptic technique when the material was subjected to longitudinal stresses in the range from zero to +/-30MPa. Observations were made while the sample was in a mechanical stressing machine. A typical grain containing bar and lancet domains at zero stress was studied. Irreversible domain subdivisions were found after application of a compression of 20MPa. A stress domain structure was observed all over the grain at a stress of +30MPa. Observation in the transition region revealed that the spread of the stress pattern under tension started at the more misoriented grains and spread to the less misoriented regions. Quantitative agreement was obtained with some earlier works but grains with mired stress and normal domain patterns and regions containing curved domains are thought to be reported for the first time.