The basic purpose of compaction is to obtain a green compact with sufficient strength to withstand further handling operations. The strength of green compact is influenced by the characteristics of the powders (apparent density, particle size and shape, internal pores etc.), the processing parameters (applied force, pressing type, and temperature) and testing conditions (strain rate etc.) Successful powder cold compaction is determined by the densification and structural transformations of powders (metallic powders, ceramic powders and metal-ceramic powder mixtures) during the compaction stages. In this paper, for understanding the factors that determine a required strength of compacted metal-ceramic powder mixtures, we present the densification mechanisms of different mixtures according to densification theories of compaction, the elastic-plastic deformations of mixture powders, the stressstrain relations and the relaxation behavior of compacted metal-ceramic composite parts and the particularities of each of them.
1. Alwahdi F.A.M., Kapoor A., Franklin F.J.: Subsurface microstructural analysis and mechanical properties of pearlitic rail steels in service. Wear 302 (2013), 1453-1460.
2. Cvetkovski K., Ahlström J.: Characterisation of plasticdeformation and thermal softening of the surface layer of railway passenger wheel treads. Wear 300 (2013), 200-204.
3. Murawa F.: Radsätze für Schienenfahrzeuge - grundsätzliche Gedanken zur Dimensionierung. EI - Eisenbahningenieur 55 (1/2004), 40-47.
The paper presents an aproximate analytic method for determination of the stored energy of plastic deformation during cold bending of metal tubes at bending machines. Calculations were performed for outer points of the tube layers subjected to tension and compression (the points of maximum strains). The percentage of stored energy related to the plastic strain work was determined and the results were presented in graphs. The influence and importance of the stored energy of plastic deformation on the service life of pipeline bends are discussed.
Milan Smetana, Klára Čápová, Vladimír Chudáčik, Peter Palček and Monika Oravcová
This article deals with non-destructive evaluation of austenitic stainless steels, which are used as the biomaterials in medical practice. Intrinsic magnetic field is investigated using the fluxgate sensor, after the applied plastic deformation. The three austenitic steel types are studied under the same conditions, while several values of the deformation are applied, respectively. The obtained results are presented and discussed in the paper.
Elastic-plasticdeformations u r of bottom plates at the point no. 2 for different values of width widths a , in which there was entire loosening of soil - foundation type B.
In the case of foundation type A, the deformations of the bottom u z do not have a significant influence on the value of radial deformations of the shell u r ( Fig. 7 ) if the soil is of uniform stiffness K z . In case of B-type foundation, there is a clear relationship between these deformations, which allows to assess the vertical deformations of the bottom plates on the
Andrej Czán, Ondrej Babík, Igor Daniš, Pavol Martikáň and Tatiana Czánová
Main task of materials for invasive implantology is their biocompatibility with the tissue but also requirements for improving the functional properties of given materials are increasing constantly. One of problems of materials biocompatibility is the impossibility to improve of functional properties by change the percentage of the chemical elements and so it is necessary to find other innovative methods of improving of functional properties such as mechanical action in the form of high deformation process. This paper is focused on various methods of high deformation process such as Equal Channel Angular Pressing (ECAP) when rods with record strength properties were obtained.The actual studies of the deformation process properties as tri-axial compress stress acting on workpiece with high speed of deformation shows effects similar to results obtained using the other methods, but in lower levels of stress. Hydrostatic extrusion (HE) is applying for the purpose of refining the structure of the commercially pure titanium up to nano-scale. Experiments showed the ability to reduce the grain size below 100 nm. Due to the significant change in the performance of the titanium materials by severe plastic deformation is required to identify the processability of materials with respect to the identification of created surfaces and monitoring the surface integrity, where the experimental results show ability of SPD technologies application on biomaterials.
Marek Kowalik, Mirosław Rucki, Piotr Paszta and Rafał Gołębski
] Wieczorowski, M., Mamalis, A.G., Rucki, M., Lavrynenko, S.N. (2008). Interferometry and scanning microscopy in asperity measurement of biomedical surfaces. Nanotechnology Perceptions , 4, 265-288.
 Dotson, C.L. (2016). Fundamentals of Dimensional Metrology . Cengage Learning.
 Messerschmidt, U. (2010). Dislocation Dynamics During PlasticDeformation. Springer.
 Kluz, R., Trzepiecinski, T. (2015). Analysis of the optimal orientation of robot gripper for an improved capability assembly process. Robotics and Autonomous Systems , 74, 253
Ancuta-Ioana Coseru, Valentin Zichil and Stefan Lupascu
In this paper, the authors propose a studying method for the deformation that appears before crack of ductile materials using the Lode parameter determined by the numerical calculation applied on simple models, verified in previous studies. In order to highlight the influence of the Lode parameter, the tests were performed at simple but also at compound tests. The necessity of these studies lies in the fact that the acknowledged models (the use of the integral J, the critical stress intensity factor Kc or the CPCD method) do not fully explain the phenomenon of deformation before breaking the elasto-plastic materials. The tests were imagined under the form of sets. Each set of tests was performed on smooth specimens and on specimens with a notch radius of 0.5, 2, 4 and 10 mm. Also, each set of tests was performed for pure tensile and combined tensile-torque test.
Nowadays, number of customer and environmental requirements are laid to the automotive industry. These are related to safety increase, the weight and emission reduction as well as the life-time improvement. The article presents the way to improve the corrosion resistance of the car-body components when coated steel sheets are used based on Zn-Al-Mg coatings. Thus, the life-time of the car-body is improved. Samples with conventional Zn coating and samples with advanced Zn-Al-Mg coatings were deformed by stretching and 3-point bending to 90° and 180° tests. Consequently, the samples were exposed to salt spray in the corrosion chamber. Time to red corrosion appearance and adequate percentage of corroded surface was evaluated. The results showed the better corrosion protection of Zn-Al-Mg coatings when compared to the conventional Zn coating.