Development of new composition for sHSS steel used for hot rolling mill rolls at Magnitogorsk Iron and Steel Works

Abstract

The paper presents the results of the complex scientific and research work directed on development of the new composition of sHSS steel for rolling mill rolls together with Magnito-gorsk Iron and Steel Works (MMK) and Magnitogorsk Mill Rolls Plant (MZPV). The first part includes the review of technical literature in the field of the results of roll steel examination by domestic and foreign researchers, investigation of structure and determination of properties of foreign rolling rolls, which were operated at the MMK hot rolling mill. The minimal level od sHSS steel properties for the working layer of a rolling roll, providing its operation reliability, is also determined. Laboratorial experiments were conducted at the second stage. The formed massif of ex-perimental data was processed using neural net, and as a result, the optimal chemical composition of the roll steel with high wear resistance and hardness was obtained. After processing of the re-sults of the planned experiment, the regression equation was obtained; it describes influence of the alloy chemical composition on wear resistance and hardness coefficients. Optimized composition of the alloy was developed at Magnitogorsk Mill Rolls Plant; it wad resulted in manufacture of the pilot roll sleeve in centrifugal machine. This roll sleeve was subjected to heat treatment according to the standard plant procedure. The final step included laboratorial testing of the pilot roll sleeve which was manufac-tured from steel with optimized chemical composition. It was determined that the developed composition is characterized by wear resistance increased by 27 % in comparison with the re-searched foreign analogue, as well as by similar qualitative parameters of the alloy microstructure.