Armco Inc.

Armco Advanced Materials Corporation

Jerry W Shoen

David E Margerum

A process of producing high silicon, low melt carbon regular grain electrical silicon steel having a final gauge of from 14 mils (0.35 mm) to about 6 mils (0.15 mm) or less, including the steps of providing a hot band and removing the hot band scale, if needed. The silicon steel is cold rolled to intermediate gauge and subjected to an intermediate anneal at a soak temperature of about 1650.degree. F. (900.degree. C.) to about 1700.degree. F. (930.degree. C.). Thereafter, the silicon steel is cooled in a first stage slow cooling at a rate of about 500.degree. F. (280.degree. C.) to about 1050.degree. F. (585.degree. C.) per minute down to about 1100.degree. F..+-.50.degree. F. (595.degree. C..+-.30.degree. C.). The silicon steel is then subjected to a second stage fast cooling down to from about 600.degree. F. (315.degree. C.) to about 1000.degree. F. (540.degree. C.) at a cooling rate of from about 2500.degree. F. (1390.degree. C.) to about 3500.degree. F. (1945.degree. C.) per minute followed by a water quench. The silicon steel is cold rolled to final gauge, decarburized, coated with an annealing separator and final annealed. Preferably, but optionally, the hot band is annealed prior to the first cold rolling. Preferably, but optionally, the final gauge silicon steel prior to decarburization is subject to an ultra-rapid annealing treatment at a rate greater than 180.degree. F. (100.degree. C.) per second to a temperature greater than 1250.degree. F. (675.degree. C.).

Method of making high silicon, low carbon regular grain oriented silicon

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.

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Middletown, OH, United States of America

Jerry W Shoen