Key Engineering Materials Vol. 822

Abstract: A method for determining the friction coefficient was developed and experimentally tested by comparing theoretical calculations of the relative volume of radial channels filling with various convergence angles of generating line for various friction coefficients and experimental data on the value of filling these channels. Relative volume of metal extruded into the channel was selected as criterion for simulation the channel filling conditions depending on the friction coefficient. Relative error of the experiment results doesn’t exceed 6% according to the linearized models of this criterion.

Abstract: The process of less than 90 degrees angle bending is presented in this article. Elastic-plastic deformation took place in the sample. After removing the force, the effect of elastic spring-back occurs – the angle of the part is increased by a value that depends on many parameters. The usage of an elastic element in the stamp allows us to change the angle of spring-back. This is happened doe to adjusting the height of the press stroke. This allows us to produce parts with accurate dimensions.

Abstract: Investigations of the rheological properties and the formation of the structure of stainless steel were performed. A computer model of the process of hammer forging of the turbine blades made of stainless steel 1.3 m long in the package Deform-3D was developed , with the help of which the necessary coefficients and parameters are determined to ensure maximum convergence of the calculated and experimental process data. The obtained data were used to create a mathematical model for stamping a large-sized turbine blade made of stainless steel with a length of 2.1 m. Mathematical modeling of the processes of stamping and distorting of a large-sized blade in the software package Deform-3D has been performed. The influence of process parameters on the stress-strain state (SSS), forming, temperature field in the forging at various stages of stamping. Determined temperature and deformation modes of stamping, the need for additional heating and optimal forgings geometry by stamping.

Abstract: The paper considers the technology of manufacturing flange parts using local methods of metal forming. Various technologies of manufacturing of ring blanks for the subsequent rotary forging of flanges are offered and investigated. On the basis of computer simulation, the main dimensions of the workpiece have been chosen, providing the best forming parts and the parameters of the technology mode. The results of experimental studies have shown that this technology is possible to manufacture flanges according to EN 1092 using the process of axial rotary forging with cylindrical rolls. The use of local methods of deformation of metals allows expanding the possibilities of technological processes at lower power equipment.

Abstract: Questions of thermomechanical parameters appointment under the semihot (warm) forging of metal preforms were considered. The international experience was analyzed as well. Economically effective thermomechanical conditions under semihot/warm forging, which is capable to provide a high complex of the mechanical properties of steel, are offered. The economical effect after the process integration to the industry was considered.

Abstract: Equal channel angular pressing (ECA-pressing) is an effective process to produce materials with increased mechanical properties and no change of billet size. In the present paper the experimental and finite element analysis results of ECA-pressing investigation were obtained. The influence of contact friction condition on flow nature and stressedly-deformed state of metal during ECA-pressing was studied.

Abstract: The results of computer simulation processing and determination of limiting degree of deformation by the Kolmogorov criterion are presented. The derivation of the dependence for the evaluation of the destruction of low-plastic materials at the edge is made at bend angle of 90⁰

Abstract: This article describes the practical application of hot extrusion for compaction of magnesium shavings in semi-finished products and the study of the influence of process parameters on the mechanical properties of the obtained MA5 (AZ80) magnesium alloy bars. Production of bars was carried out at different heating temperatures and plastic deformation degree to find technology provide the best combination of tensile and compressive properties. The resulting bars are somewhat higher in strength characteristics than the strength of deformed cast bars made from MA5 alloy, however, they are significantly lower in ductility.

Abstract: In this work, the technology of Al-Gd alloys production has been developed, in which gadolinium is added as an alloying element during induction melting or in the composition of Gd₂O₃ disperse particles in the complex use of powder metallurgy and foundry technologies. The design of Vibration-jet agitator (VJA) and technology of its use for introduction of disperse particles into aluminum melts were developed. Aluminum alloys and dispersion-strengthened composites containing gadolinium have been obtained, their structure and neutron absorption properties has been studied.

Abstract: Novel copper-nanocarbons – Cu-fullerene soot/reduced graphene oxide composites with 0-5 wt.% carbon additions were fabricated by spray drying method and hot pressing procedure. In order to obtain the homogeneity of composites, the spray drying integrating with shear mixing was adopted. The microstructure and properties of the composite materials were investigated and compared to Cu–graphite composite, which was prepared under the standard technology. The interface, depending on the nanocarbons addition, prevents copper aggregation, and inhibits the copper grain growth. The compact composites hardness was significantly higher as compared with Cu-CNTs and Cu-Graphite composites of the same carbon concentration with small reduction of the thermal conductivity.