NEW CASTING ALLOYS FOR USE UNDER EXTREME CONDITIONS AND SOME TECHNIQUES OF MAKING CASTINGS FROM THEM

The article studies new heat-resistant and wear resistant materials for operation under extreme conditions, especially in the power industry. The methods that improve the quality of a metal in metal castings through the influence of alloying elements on its structure and properties have been considered. These methods are very effective for reducing the tendency of a metal to form a coarse–grained structure. The paper describes optimal techniques for melting special alloys in induction and electric furnaces. A set of rules for the selection of a melting temperature before pouring a metal into the casting forms depending on the dimensions, wall thickness, geometry of castings have been determined. The behavior of new alloys under the conditions of high temperatures, aggressive environments has been studied.It has been established that heat–resistant Cr–Al steels exhibit high heat resistance and wear resistance properties; they 6–8 times surpass Cr–Ni steels in oxidation resistance. The proposed Cr–Mn cast iron processed in an integrated manner with REM (rare earth metals) and Ti is superior to a basic cast iron in conditions of a heavy wear. Numerous industrial trials confirm the usefulness of recommended new casting materials for use under extreme conditions.The article studies new heat-resistant and wear-resistant materials to work under extreme conditions, especially in power industry. The methods for improving the quality of a metal in metal castings through influence of alloying elements on its structure and properties, methods of reducing its tendency to form a coarse-grained structure have been considered. The paper describes optimal techniques for melting of special alloys either in induction or in electric furnaces and selection rules of melt temperature before pouring the metal in the casting forms depending on the dimensions, wall thickness, geometry of castings. The behavior of new alloys at high temperatures, aggressive environment and heavy wear has been studied. Numerous industrial trials confirm the usefulness of recommended new casting materials to work under extreme conditions