Paper Title
Change of Microstructure of NB MicroAlloyed Steel at Start of the Plastic Flow during the Cold Deformation

Microstructure has significant impact on the properties and behavior of materials, so it is a subject of intensive investigation nowdays. In this paper, special attention is paid to study on the beginning of the plastic material flow in Nbmicroalloyed steel during the cold deformation. Specific behavior of this steel can present a significant problem during the metalworking in terms of inhomogeneous deformations appearance. Due to many available methods now it is possible to observe what is happening during the deformation of certain material. Hence, investigation of material flow and stress distribution in deformation zone is growing up today. Therefore, the aim of this work was to establish the change of microstructure of low carbon steel microalloyed with niobium at start of the plastic flow during the cold deformation. For that purpose Nbmicroalloyed steel was hot rolled into strip and then static tensile test was carried out. Thermography method was used to study the changes of temperature during the deformation. Microstructure before and after deformation was observed by scanning electron microscope. These investigations showed the fine grained ferrite-pearlitic microstructure and its significant changes at start of the plastic flow during the cold deformation. Keywords - Cold Deformation, Microstructure, Niobium Microalloyed steel.