Armco Inc.

Russel L Young

Jerry W Schoen

David E Margerum

A process for improving the core loss of magnetic materials of the type having a plurality of magnetic domains and which may have an insulative coating such as a mill glass, an applied coating, or both. The magnetic material is subjected to a local heat treatment employing radio frequency induction heating, radio frequency resistance heating, or electron beam resistance heating to induce artificial boundaries. Thereafter, the magnetic material is subjected to an annealing treatment.

Local heat treatment of electrical steel

A process for improving the core loss of cube-on-edge grain oriented silicon steel. At some point in its routing after at least one stage of cold rolling and before the final high temperature anneal during which secondary grain growth occurs, the electrical steel is subjected to local annealing across its rolling direction creating bands of enlarged primary grains. These bands of enlarged primary grains regulate the growth of the secondary cube-on-edge grains in the intermediate unannealed areas of the electrical steel strip during the final high temperature anneal, and are themselves ultimately consumed by the secondary grains, providing a cube-on-edge grain oriented electrical steel with smaller secondary grains and reduced core loss.

Local annealing treatment for cube-on-edge grain oriented silicon steel

A radio frequency induction heater for locally heating a metallic work piece. The induction heater comprises an elongated conductor surrounded by a core of magnetic material having a narrow slot formed therein serving as the inductor core air gap. The conductor is connected across a source of radio frequency current. The induction heater is located adjacent the metallic work piece with the inductor core air gap very near (and preferably in contact with) that portion of the metallic work piece to be heated. When the radio frequency current is caused to pass through the conductor, the gap concentrates the flux entering the work piece, inducing voltages in the work piece resulting in eddy currents which flow in the work piece along and parallel to the gap. This, in turn, results in the rapid local heating of a narrow band of the work piece.

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Collinsville, OH, United States of America

Russel L Young