Ultra-rapid heat treatment of grain oriented electrical steel
AssigneeArmco Advanced Materials Corporation
InventorsJerry W. Shoen, David E. Margerum
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Abstract
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.
Claims8
A process for controlling secondary grain growth and improving the magnetic properties of grain oriented electrical steel strip containing less than 6.5% silicon, said process comprising the steps of subjecting said strip of final gauge to an ultra-rapid annealing treatment at a heating rate above 100.degree. C. per second (180.degree. F. per second) to a temperature above 675.degree. C. (1250.degree. F.), decarburizing and subjecting said strip to a final high temperature anneal for secondary growth, whereby said strip has secondary grains of reduced size a degree of texturing above 90% in the (110)[001] direction and improved core loss, which improvement will survive a stress relief annealing without any significant change in magnetic properties.
Dependencies are inferred from the claim text.