Studium mezilamelární vzdálenosti v závislosti na procesu řízeného ochlazování v profilovém výrobku perlitické oceli

Abstract

The thesis focused on the study of the interlamellar distance depending on the controlled cooling process in a profile product of perlite steel. The theoretical part is devoted to the description of diffusion and non-diffusion transformations of austenite. Subsequently, methods for the evaluation of the interlamellar distance of pearlite will be described. In the next part, the chapter will focus on the influence of microalloying elements on perlite steels and then the effect of interlamellar distance on mechanical properties. The last chapter is devoted to the heat treatment of rails. In the experimental part, the interlamellar distances of perlite are evaluated and compared with the resulting mechanical properties, mainly hardness, tensile strength and ductility, of four sets of samples from steels A, B and C for the production of rails with different controlled cooling parameters. The results show that in most of the samples an increase in hardness is achieved when the interlamellar distance values are reduced. For the samples with increased alloying elements, mainly Cr, there was an unusual behaviour of the interlamellar distance in the centre and at the top of the rail head. The total cooling time using higher pressures may increase the mechanical properties of the steel.