PRODUCTION OF DIRECTIONAL SILICON STEEL PLATE HAVING EXCELLENT REPEATED FLEXING CHARACTERISTIC

摘要

PURPOSE:To obtain a directional silicon steel plate having an excellent repeated flexing characteristic in final finish annealing wherein a silicon steel blank material is cooled down to a specific temp. by specifying the component and pressure of the atmosphere in the inner case of a box type annealing furnace. CONSTITUTION:Argon alone or s gaseous mixture of hydrogen and argon is used for the atmosphere in an inner case in cooling stage down to 600 deg.C final finish annealing temp. in the stage of subjecting a silicon steel blank material having a final plate thickness to decarburization annealing then coating a separating agent for annealing and subjecting the same to final finish annealing in the inner case of the box type annealing furnace. The pressure in the atmosphere is maintained highe by >=2mm. water column than the external pressure of the inner case. The infiltration of nitrogen into the steel is thus prevented and the directional silicon steel plate having an excellent repeated flexing characteristic is stably produced.