Basic Characteristics of Widmanstätten austenite in goes

Abstract

Twin roll strip casting is an advanced technology for production of thin strips with the thickness of several millimetres. Recent progress in twin roll strip casting makes it possible to apply this technology for the production of grain oriented electrical steels (GOES). Optimization of technological processing of GOES using this revolutionary technology requires the detailed knowledge about microstructure evolution. Cooling of GOES thin strips in the  +  phase field is accompanied by the formation of austenite in the form of Widmanstätten laths. This paper summarises basic knowledge about the formation and subsequent decomposition of Widmanstätten austenite in GOES thin strips. Attention is paid to nucleation of Widmanstätten austenite, its growth in the matrix of -ferrite, pinning of austenite/ferrite interfaces by sulphides, the formation of epitaxial ferrite, partitioning of carbon and finally to the decomposition of Widmanstätten austenite either to pearlite or plate martensite. Phase transformations were studied by a combination of l ight microscopy, XRD, SEM + EBSD and TEM.