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Mechanical processing of cast workpieces in the process of producing metal components having a complex structure and high dimensional and geometric accuracy requires significant energy and material costs, which can be reduced in case of using special types of casting. It is not possible to eliminate completely the mechanical processing of the workpieces due to the thermal characteristics of their production, such as shrinkage. To eliminate this demerit, we manufacture lost wax models by pressing wax-like powder model masses without preheating. It has been experimentally found that the accuracy of porous pressed models is 1 or 2 qualities higher than that of conventional smelted models. The elastic aftereffect of the material hinders the wide implementation of this process. This elastic aftereffect of the material leads to a smaller change in the geometry of the final product than when using the conventional process; however, it must be taken into account in designing molds. The final dimensions of the mold and the parameters of the process of making compacts from the material of a specific brand are determined predominantly during experiments. The magnitude of the elastic aftereffect depends on a number of rheological parameters of the process; therefore, the prediction of the stress-strain state of compacts from wax-like model compositions by means of mathematical calculations seems to be relevant. The paper presents the results of the stress-strain state modeling of compacts from a number of waxy-like materials using the finite element method in comparison with the results of the field experiments. This comparison allows us to obtain reliable data about real thermophysical processes occurring during the compaction of wax-like model compositions. This information is applicable in the practice of obtaining pressed smelted models of high dimensional and geometric accuracy. [ABSTRACT FROM AUTHOR]

The use of resource-saving technologies at enterprises is one of the steps to reduce production costs. This enables one to gain advantages within a competitive market economy. For foundry, aluminothermy is an example of such technological methods. Technologies based on the use of aluminothermy allow cast blanks with required properties to be produced using engineering and metallurgical wastes, such as slag, ferrous and non-ferrous metal chips, with concomitant savings of raw materials and energy resources. In the process of aluminothermy, the temperature of the reaction products reaches the values of above 3000 °C, and it is difficult to control. To reduce the temperature of the metal phase, various methods are applied, for example, addition of inert fillers to the composition of mixtures, as well as holding of the melt in a crucible before pouring. The paper considers the regularities of the influence of the process parameters of aluminothermy for the production of cast elements on the chemical composition and structure of experimental samples, e.g. the content of reducing agent in thermite mixtures and the holding time of the resulting melt in the crucible before pouring. [ABSTRACT FROM AUTHOR]

The specific feature of obtaining a permanent joint of elements produced from carbon alloys is the formation of mainly quenching structures in the heat-affected zone of the weld. Among the methods aimed at reducing this phenomenon, additional thermal methods of impact are widespread, consisting in preheating of the joint zone and slow cooling of the deposited metal. Such methods seem to be cost-intensive and the results are difficult to control. It determines the relevance to find solutions aiming at eliminating the quenching structures of the weld and heat-affected zone. To solve this problem a series of experimental studies has been carried out to form the structure and properties of the heat-affected zone of the weld made by automatic welding with the help of flux-cored wire with thermite filler. The specific feature of using this wire is weld formation when the heat enters the joint zone of the elements simultaneously both from the electric arc and exothermic process, due to the aluminothermic component. As the result of the study, permanent joints made of St3 steel and 45 steel have been obtained; their structures and stress-strain properties are also presented. [ABSTRACT FROM AUTHOR]