Abstract: The grain structure of electrical steel strip is tested by inducing a magnetic flux field into the strip by pole pieces at opposite sides of a permanent magnet. A magnetic detector head between the pole pieces responds to the leakage of flux as the steel strip and/or magnetic detection undergoes relative movement. A recorder is used to identify banding and mixed grain structures which cause a smaller flux leakage amplitude than larger desired grains.

Abstract: An improved apparatus is disclosed for measuring the surface insulation characteristics of coatings on magnetic materials. This apparatus comprises an insulative button block having a plurality of protruding contact buttons stationarily mounted therein, with each contact button provided with a substantially flat contact surface, and with all contact surfaces lying substantially in the same plane. The apparatus further includes a press for urging the contact surfaces against the coated surface of the magnetic material, the electric circuitry necessary to apply a predetermined voltage potential between the contact surfaces and the magnetic material, and an ammeter to measure the current flow through the coating.

Abstract: Continuous testing apparatus for determining the magnetic characteristics of a strip of moving material including a flux inducing and pick-up device to induce a quantity of flux into the material and dual voltage output producing coils for producing different voltages from material having the same magnetic permeability, and circuit means coupled with the dual coils to produce an output voltage which is a characteristic of the ratio of the voltage produced by one of the coils and the difference between the voltages produced by both of the coils. The invention also includes the method of obtaining a profile of the coil of the material throughout the entire length thereof.