Using thermal cycling at peritectic transformation temperatures for carbide phase crushing during crystallization

Abstract

Problem statement. Using high-temperature thermal cycling in the field of peritectic transformation to obtain atomized high-speed steel structure during its crystallization. Method. Experimental samples were obtained using a structure and hardening test facility which makes it possible to use a computer-aided high-temperature thermal cycling + hardening combined mode, fix the structure at desired temperature and crush carbide phases. Results. It has been found that during thermal cyclic treatment the chemical composition of carbides and phase composition of steel change which results in crushing of carbide particles and their more uniform distribution in the austenitic matrix. The scientific novelty consists in determining the effect of thermal cyclic treatment that occurs in the liquid-solid region in R6M5F3 steel on the structure formation which is characterized by a decrease in dendritic segregation and the sizes of carbide phases and their more uniform distribution. Practical significance. High-temperature thermal cyclic treatment of cast billets during their crystallization makes it possible to obtain more uniform and atomized steel structure. This will reduce costs required for further multiple heat treatments which are still used at factories in the manufacture of cutting tools and therefore reduce the cost price of the finished tool. Moreover, a more uniform distribution of alloying elements and crushed carbide phases will ensure increased secondary hardness and durability of cutting tools made of R6M5F3 steel.