Armco Inc.

Armco Advanced Materials Corporation

David E Margerum

Russel L Young

Jerry W Shoen

Ultra-rapid annealing of grain oriented electrical steel to a temperature prior to the final high temperature anneal results in improved texture and smaller secondary grain size. The ultra-rapid anneal requires heating the strip to a temperature above about 675.degree. C. (1250.degree. F.) at a rate above 100.degree. C. per second (180.degree. F. per second). The ultra-rapid anneal is performed after the first stage of cold rolling and prior to or as part of the decarburization anneal. The material will survive a subsequent stress relief anneal and may be further improved by various domain treatments. The ultra-rapid anneal increases productivity and procedures improved core loss properties.

Ultra-rapid heat treatment of grain oriented electrical 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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Middletown, OH, United States of America

David E Margerum