Materials Science Forum Vol. 946

Abstract: The improved technology of position control and alignment of the continuous casting machine (CCM) equipment based on high-precision online geodetic measurements is considered. The mathematical model for the technological axis of the continuous casting machine, the technique of the rational alignment of the machine’s equipment and the software implementing this technique are proposed. The application experience of the developed technique for control and aligning the equipment of continuous casting machines of different types is shown. The data on the efficiency of the technique for continuous casting machine equipment and its impact on the quality of a continuously cast ingot are presented.

Abstract: The influence of various methods of activation on the graphite particles average size and micro-relief of particles have been studied. It has been experimentally proved that the size of graphite particles decreases after the process of mechano-activation, however graphite particles don’t change significantly after being processed by chemical activation. It should be noted that in the course of chemical activation the state of particles surface varies on shearing cuts. Particles’ surface can be described as a poly stratified system, comprising separate complex-structured buildups of the “rosette” type, where the graphite petals are located around the reinforcing rod. Moreover, the graphite petals are placed at different angles to each other, and they are of different thickness. The empty space between these buildups is filled with graphite particles, their petals being orientated freely. The particles size decrease and the change in the particles surface state are followed by their porosity increase, which, in its turn, leads to the fact that graphite particles’ surface becomes “super-hydrophobic” and helps the capillary forces resist the filtration of the melt into the pores of graphite particles.

Abstract: The paper describes the advantages and prospects of using the physical methods of melts processing in the production of aluminum alloys and cast aluminum matrix composites. Classification of the physical methods of the melt processing by the state of metal during the processing period and by the physical principle of the imposed effects is proposed. The influence of physical processing of melts on the structure of aluminum matrix composites depending on the type of imposed influence and the origin of the reinforcing phases is shown. The positive effect of thermo-temporal treatment on the structure of materials was confirmed on example of in-situ composites of Al-Mg₂Si system, it includes reduction in the average size of endogenous reinforcing phases and changing their morphology to a more compact.

Abstract: The paper presents the methods for forecasting the structure and geometrical parameters of casts by using the ProCAST system of engineering analysis. Based on experimental studies and computer simulation, a regularity between the supercooling rate of aluminium alloy on the one hand and the nucleation rates and crystal growth rates on the other has been established. There have also been established dependencies describing the change in the plasticity modulus, the coefficient of thermal linear expansion, Poisson's coefficient within the temperature range of 20 to 1000°C for cores made from α-set mixture. The computer simulation based on the experimental data of the processing of silumin casts made it possible to forecast the alloy structure with the probability level of 95%, and to calculate the accuracy of hindered contraction of the alloy with accuracy equal to ± 1.5%.

Abstract: The article deals with technologies of refining and inoculating casting alloys with the use of nanostructured diamond powder, as well as stimulation technique on molten metal including processing of the liquid alloy with nanosecond electromagnetic pulses. The developed method of cast iron inoculation allows to eliminate the flare and to increase the physical and mechanical properties of the castings through the grain refining and the decrease of chilling tendency during crystallization of the liquid alloy. Inoculating of aluminium alloys by high-melting particles of a nanostructured diamond powder leads to the grinding of structural constituents, including conditions for dispersing hardening intermetallics during postbaking of such castings. As a result, foundry and physicomechanical properties of castings are significantly improved.

Abstract: For cost reduction of the molds manufacturing, as well as environmental load in foundries sodium silicate binder is often used. However, without treatment with special compositions that accelerate curing and improve their properties, sodium silicate molds have insufficient thermal spalling resistance and often cause the rejection of castings made of heat-resistant alloys. As a result of the research, there was developed a technology of chemical drying of the sodium silicate cover layers in investment casting with the use of aluminoborbophosphate concentrate. It allows to reduce the production time of ceramic molds by 2...3 times, as well as to increase their strength either before baking or after it by 20...25 %. At the same time, as a result of softening effect of aluminoborbophosphate concentrate after baking and cooling of the specimens there has been observed a significant reduction of their retained strength and, as a consequence, better knockout of fire-resistant shells. Industrial tests of the sodium silicate cover chemical drying showed a significant reduction of the investment castings rejection due to the insufficient thermal spalling resistance and the reduction of the cleaning processing time of casting made of heat-resistant alloys.

Abstract: The paper describes the theory of developing the heat-resistance criterion for disposable ceramic molds exposed to poured metal, creating a computational and experimental method for computing the heat resistance by rapidly heating the mold by an electric arc, as well as analysis of comparative data on quartz, dinas, and electric-corundum molds from the standpoint of the developed criterial-evaluation theory. In this case, the heat resistance is of one-time character, as this mold sustains only a single casting. Computational and experimental data indicate a low heat resistance of β-quartz, making them non-recommendable for annealing and metal pouring if there is not supporting filler. Molds based on electric-corundum or dinas fillers are free of such drawbacks, with the latter being considerably cheaper. The use of tridymited dinas powders is effective after grinding the spent dinas lining of electric furnaces.

Abstract: The paper presents the results of the analysis of thermal state of continuous cast bloom on the stage of incomplete crystallization in the area of possible places of application of technology of Mechanical Soft Reduction (MSR), received during simulation on mathematical model, which was implemented in the software package using the finite element method. For the conditions of continuous cast bloom with a cross section of 360-400 mm, we studied the characteristics of temperature change over the cross section of the bloom, the growth dynamics of the solid shell, the number of the solidified component, and the end point position of solidification depending on the technological parameters for continuous casting of A516, 5140 1070 and AISI steel brands. The obtained data on the thickness of the crystallized shell of continuous cast bloom and the amount of solid phase depending on the casting speed and steel grade allowed us to conclude about the possible place of installation of the MSR unit. The results of mathematical simulation can be transferred in a digital form to the strength model of deformation of continuous cast bloom at the stage of incomplete crystallization.

Abstract: The features of a technology application AlpHaset process in Russia are considered, as well as the requirements imposed on the used materials, especially to forming sand, the reasons, which lead to searching for the technology, eliminating defects of this process, and the capability of using resins and hardeners of the Russian fabricator. The question about the opportunity of substitution of resin for liquid glass for this process was elaborated. The experience of AlpHaset technology process was learned, with the usage of a liquid glass, the extent of a regeneration of such a mixture at the factories of Russia was also studied. Laboratory studies were done and recipe of the mixture was created for AlpHaset process, where a resin is completely replaced with a liquid glass. At the same time, the work on receiving a reclaim from an aged dump of liquid glass mixture, which could serve as a substitute of fresh sand in a compounding for AlpHaset process, was completed. As the result, there was created and embedded a recipe of a mixture, where the reclaim (which is completely replacing fresh forming sand), received from aged dumps of traditional liquid glass mixture for process CO2, was used. The compounding of forming a mixture began to look as follows: a reclaim of liquid glass mix, a reclaim from the line, a liquid glass, and hardener.

Abstract: In the transition to modern high intensive processes of smelting there had been reversed technologies structures to get carbon content in cast iron. A re-carburizing agent, that can be one of the most significant reasons of occurrence of defects of the cast, and deformed metal and decrease of the level of properties have been identified. There was not only made the decarburizing agent of modern technology of production of pig-iron essential element (particularly synthetic), but also resulted in many of variants of its realization from the standpoint of level decarburizing, type, using re-carburizing method of decarburizing technological phase, where enter of carbonaceous materials. Particularly sharply process of execution re-carburizing influences receipt of synthetic pig-iron in induction crucible furnaces of industrial frequency from metal works, which contained 80-90% of steel breakage. Then, it is necessary to raise the content of carbon from 0,3 to 3,0-3,8% (depending on the pig-iron mark). It forces foundry enterprises to approach with big care at a choice of existing materials, which it is possible to use as decarburizing and to verify carefully, which is appearing at the market. In work application there are considered variants of using carbon-carbide-silicon mixture UKKS-31 at melting of grey pig-iron in induction, crucible furnaces, intended for pig-iron melting. The cost comparison is presented between traditional technology and with using mix UKKS-31.