Papers by Author: Małgorzata Witkowska

Abstract: The present examination is a part of project concerning a deformation behavior of duplex type ferritic-austenitic stainless steels. The investigations included the analysis of ferrite and austenite microstructures formed in cold-rolled sheet of super-duplex stainless steel, major deformation mechanisms operating in both constituent phases and changes in morphology of two-phase structure after the thermo-mechanical treatment and subsequent cold-rolling. Duplex type stainless steels develop the band-like ferrite-austenite morphology in the course of hot- and cold-rolling. This specific two-phase structure creates different conditions for plastic deformation in comparison to single phase steels. The interaction of both phases upon deformation exerts fairly significant influence on structure and texture formation in both constituent phases and in consequence affects the material properties and its behavior upon further processing.

Abstract: The present examination concerns a comparison of rolling texture development in two stainless steels of duplex type with different intensities of ferrite and austenite initial textures after a preliminary treatment, namely; clearly defined strong textures of both phases in one steel and nearly random textures in the case of the second one. Essentially the constituent phases in both duplex steels tend to develop the rolling textures comparable with those in single phase steels. However, the final textures display certain differences in comparison to the typical ferrite and austenite rolling textures. In both duplex steels the formation and character of the final deformation textures is strongly influenced by the band-like morphology of the ferrite-austenite structure and the process of texture formation proceeds in different way depending on the initial orientation distribution.

Abstract: A development of deformation textures was examined in ferritic-austenitic duplex type steel subjected to cold-rolling within the range up to 90% of reduction by applying different rolling schedules. The investigations included X-ray phase analysis, texture measurements and microstructure observations by means of light microscopy. The experimental results indicate at the occurrence of strong initial textures in both component phases after preliminary thermo-mechanical treatment. Formation of the ferrite-austenite banded structure in the course of rolling along with the stability of major texture components, related by Bain orientation relationship, exert considerable effect on the development of the ferrite and austenite rolling textures.