Vliv intenzivní deformace za tepla na výslednou strukturu nízkouhlíkové oceli

Abstract

The presented diploma thesis deals with the influence of intense deformation under heat, as well as other thermomechanical forming conditions, on the final structural and mechanical properties of unalloyed low-carbon steel. The MAXStrain II unit, which is part of the HDS-20 simulator, was mainly used for experimental work. The microstructure of all samples deformed on the MAXStrain II unit consisted of a mixture of ferrite and perlite (minor proportion). In the case of samples cooled after deformation in an accelerated manner, turbidity components were also detected in the microstructure (up to 5%). In all cases, during the tests on the MAXStrain II unit, the resulting ferritic grain became finer and the hardness of the examined steel increased (compared to the initial structural state). The resulting ferritic grain decreased and at the same time the hardness increased with decreasing deformation temperature and in the case of lower total deformation intensity also with a longer inter-hit break. The chosen cooling rate had a significant effect on the resulting ferritic grain size and the hardness of the investigated steel.