Investigation of the Efficiency of Reversible Radial-Shear Rolling to Obtain a Gradient Ultrafine-Grained Structure in 5KHV2S Steel

Abstract

It has long been proven that radial-shear rolling has a number of advantages over other methods of pressure treatment, which allows obtaining an ultrafine-grained structure, including gradient, in various ferrous and non-ferrous metals and alloys. Therefore, radial-shear rolling plays an important role in the production of high-quality bars with an increased level of properties. This work, carried out within the framework of grant № AP14869135, funded by the Committee of Science of the Ministry of Science and Higher Education of the Republic of Kazakhstan, is devoted to the study of reversible radial-shear rolling of 5KHV2C steel and the identification of its influence on the possible gradient modification of the microstructure of this steel grade. In the course of experimental studies, it was proved that during the deformation of a bar made of 5KHV2C steel with an initial diameter of 36 mm, a gradient microstructure is formed along the cross section of the bar on a radial-shear rolling mill with an extraction equal to 4, i.e. up to a diameter of 18 mm. The cross-section structure of the bar varies from an elongated rolling texture in the central part of the bar to an equiaxed ultrafine-grained microstructure in the peripheral layers of the bar. The gradient character of the microstructure is also confirmed by the distribution of microhardness over the cross section of the bar: microhardness in the peripheral layers of the bar is on average 1.7 times higher than in the central part of the bar.