Ilya V. Chumanov ¹, Valeriy I. Chumanov ¹, Andrey N. Anikeev ¹

Affiliations
1 Physical Metallurgy Department, South Ural State University (National Research University), Zlatoust Branch, RU

Abstract

Over the last decades the investigations have been actively under way to develop the methods, aimed at increasing the strength characteristics of metals. To increase the strength indicators it is most practicable to apply the metal processing technologies, focused on refining the grain structure. However, now the industry employs the processes, by applying which metals form clearly expressed coarse-grain structure, for example, casting. The fact that the casting manufacturing technologies are widely spread is related to their low cost of production. The cast items, in most cases possess coarse-crystalline structure, which affects negatively the chemical and the physical/mechanical characteristics of materials. Refining the coarse-grain structure represents a difficult (from the view point of technology and economic effectiveness) technical task. One of the most prospective approaches to refining the material grain structure is the way of grinding it at the stage of solidification upon melting. This can be achieved by introducing the additional particles in the molten pool, which perform the function of “micro-coolers” (crystallizing centers); they, merely by their presence, make obstacles for the movement of grain boundaries during crystallization. One more prospective method for structure refining is that of hot plastic deformation, when the structure is refined mechanically. The article gives an account of the process and of the results of the experiments to obtain castings with refined structure due to introducing the disperse particles in the melt at the casting stage. Part of the obtained castings underwent hot plastic deformation. While investigating the obtained materials the alteration of the microstructure in the castings has been estimated depending on the amount of introduced particles, and also the investigations on hardness and wear resistance alteration were undertaken both in cast and in deformed conditions.

Keywords

Disperse and Dispersive Hardening, Grain Refinement, Metal Hardness, Microstructure, Molded Pieces, Plastic Deformation by Forging, Strength, Wear-Resistance

Full Text

   

Ilya V. Chumanov ¹, Andrey N. Anikeev ¹

Affiliations
1 Physical Metallurgy Department, South Ural State University (National Research University), Zlatoust Branch, RU

Abstract

Metal-based constructional materials will always be demanded by the companies of mechanical engineering, space and other industries. The most interesting is studying the methods, based on introducing micro-, ultra- and nanodisperse particles in liquid or hard-liquid melt, that is disperse hardening. Such methods of obtaining composite materials are known for a considerable period of time, though their application has been limited; they have been employed in different industries, but not widely. The article describes different methods of obtaining composite materials based on introducing the disperse particles; also a new original method is suggested, affording obtaining composite materials with predictable characteristics different in various areas of one and the same manufactured item. The article also describes the process, the experimental results, the findings of the investigations of the experimental material structure and properties, obtained by disperse hardening method. Disperse particles of wolfram and titanium carbides were introduced into solidifying melt while casting steel on the centrifugal casting machine. Such method of introduction allowed obtaining composite cylinder-shaped billets with different content of the introduced particles across the section (due to different densities of the introduced particles and of the hardened metal). The obtained samples were prepared and investigated for macro- and microstructure alteration across the section. The result of the study is represented by the data on the introduced particles distribution across the sections of the obtained samples.

Keywords

Centrifugal Casting, Composite Materials, Hard Alloys, Macro- and Microstructure, Methods of Introducing the Disperse Particles, Wolfram and Titanium Carbides

Full Text

   

Andrey N. Dildin ¹, Evgeny A. Trofimov ¹, Ilya V. Chumanov ¹

Affiliations
1 South Ural State University, Russia

Abstract

Background/Objectives: This work was aimed at experimental studying the laboratory process and the results of liquidphase carbon (coke) reduction of the steelmaking slag conducted to obtain the metal and oxide phases which can be used in the metallurgical industry and building materials industry. Methods: The slag from the slag dumps of Zlatoust Metallurgical Plant (the Russian Federation) was an object of the study. The composition of the experimental samples of metal and slag was determined by electron probe microanalysis. Findings: The conducted experiments give grounds to assert that the process allows recovering almost completely iron, chromium and nickel contained in the slag. Major part of manganese, as well as some other components, including valuable elements – tungsten, molybdenum, titanium and vanadium, also passes into the molten metal. It has been shown that liquid-phase recovery of slag is acceptable to be carried out at temperatures of about 1500-1550°C. In this case, the slag reduction time (after heating the mixture up to the operating temperature) should not exceed 30 minutes. For a more complete recovery of valuable metals it is recommended to use the moment of the ‘boiling’ (intensive separation of gaseous carbon oxides) period completion as an indicator of the isothermal time end. Improvements/Application: Useful products of the recovery process are liquid metal and heavy metal-depleted oxide melt consisting mainly of calcia, silica, magnesia and alumina which may be used in cement manufacturing.

Keywords

Experimental Study, High-Temperature Processes, Liquid-Phase Reduction, Steelmaking Slags.

Full Text