STRAIN-INDUCED TRANSFORMATION TO ULTRAFINE MICROSTRUCTURE IN STEEL

摘要

PROBLEM TO BE SOLVED: To provide a method of producing a steel strip having one or more regions of an ultrafine microstructure. SOLUTION: The method comprises: a step of casting the steel strip of an austenite phase having a grain size greater than 50 microns; a step of cooling the newly cast steel strip of an austenite phase without working to form a hoop having a thickness of <10 mm at a temperature ranging from 600 to 950; and a step of deforming the cooled steel strip at a thickness reduction ratio ranging from 20 to 70% when the steel strip is still the austenite phase and before a substantial phase transformation is started, 90% of the microstructure transformed into the ultrafine microstructure during the deformation or within one second thereafter in the one or more regions of the microstructure. COPYRIGHT: (C)2007,JPO&INPIT