Publikační činnost Katedry tváření materiálu / Publications of Department of Materials Forming (633)

Permanent URI for this collectionhttp://hdl.handle.net/10084/64758

Kolekce obsahuje bibliografické záznamy publikační činnosti (článků) akademických pracovníků Katedry tváření materiálu (633) v časopisech registrovaných ve Web of Science od roku 2003 do roku 2022.
Do kolekce jsou zařazeny:
a) publikace, u nichž je v originálních dokumentech jako působiště autora (adresa) uvedena Vysoká škola báňská-Technická univerzita Ostrava (VŠB-TUO),
b) publikace, u nichž v originálních dokumentech není v adrese VŠB-TUO uvedena, ale autoři prokazatelně v době jejich zpracování a uveřejnění působili na VŠB-TUO.

Bibliografické záznamy byly původně vytvořeny v kolekci Publikační činnost akademických pracovníků VŠB-TUO, která sleduje publikování akademických pracovníků od roku 1990.

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Now showing 1 - 20 out of 136 results

Hot deformation behavior of non-alloyed carbon steels
(MDPI, 2022) Kawulok, Petr; Opěla, Petr; Schindler, Ivo; Kawulok, Rostislav; Rusz, Stanislav; Sauer, Michal; Konečná, Kateřina
The hot deformation behavior of selected non-alloyed carbon steels was investigated by isothermal continuous uniaxial compression tests. Based on the analysis of experimentally determined flow stress curves, material constants suitable for predicting peak flow stress sigma(p), peak strain epsilon(p) and critical strain epsilon(crDRX) necessary to induce dynamic recrystallization and the corresponding critical flow stresses sigma(crDRX) were determined. The validity of the predicted critical strains epsilon(crDRX) was then experimentally verified. Fine dynamically recrystallized grains, which formed at the boundaries of the original austenitic grains, were detected in the microstructure of additionally deformed specimens from low-carbon investigated steels. Furthermore, equations describing with perfect accuracy a simple linear dependence of the critical strain epsilon(crDRX) on peak strain epsilon(p) were derived for all investigated steels. The determined hot deformation activation energy Q decreased with increasing carbon content (also with increasing carbon equivalent value) in all investigated steels. A logarithmic equation described this dependency with reasonable accuracy. Individual flow stress curves of the investigated steels were mathematically described using the Cingara and McQueen model, while the predicted flow stresses showed excellent accuracy, especially in the strains ranging from 0 to epsilon(p).
Effects of temperature (in)homogeneity during hot stamping on deformation behavior, structure, and properties of brass valves
(Wiley, 2021) Kunčická, Lenka; Kocich, Radim
Herein, assessing the effects of initial temperature (in)homogeneity on a hot-stamped CuZn40Pb2 medical gas valve (fitting) via numerically and experimentally defining mutual relations of selected deformation parameters and optimizing temperature distribution within the original semi-product heated via induction are focused. For these purposes, three preheating regimes are simulated, and deformation behaviors are evaluated. The predicted results are validated by experimental stamping and subsequent evaluation of the structure and properties of stamped fittings. The results show that preheating the semi-product with a certain temperature gradient occurring between the axial and (sub)surface regions is favorable, as homogeneous initial temperature distribution results in rapid surface cooling by the effect of heat transfer from semi-product to die, which imparts inhomogeneous stress distribution, local changes in structural phases, and possible occurrence of oxides. Too low (sub)surface temperature of the semi-product can result in a significant (local) increase in flow stress, which consequently results in the danger of occurrence of forming defects. The brass fitting stamped with the optimized preheating procedure features an average grain size of 5.8 mu m, uniform grains' orientations with maximum texture intensity of two times random, and ultimate tensile strength of almost 400 MPa, while maintaining elongation to failure of more than 35%.
On various multi-layer perceptron and radial basis function based artificial neural networks in the process of a hot flow curve description
(Elsevier, 2021) Opěla, Petr; Schindler, Ivo; Kawulok, Petr; Kawulok, Rostislav; Rusz, Stanislav; Navrátil, Horymír
In recent years, the study of the hot deformation behavior of various materials is significantly marked by an increasing utilization of artificial neural networks, which are frequently employed for a hot flow curve description. This specific kind of description is commonly solved via a Feed-Forward Multi-Layer Perceptron architecture and rarely via a Radial Basis architecture. Both network architectures are compared to assess their suitability in the process of a hot flow curve description under a wide range of thermomechanical conditions. The performed survey is also aimed on the eventual utilization of corresponding modifications of both studied networks, namely on a Cascade-Forward Multi-Layer Perceptron and Generalized Regression network. The main results have shown that the Feed-Forward Multi-Layer Perceptron architecture represents a good choice if very high accuracy is a crucial goal. However, in the case of this architecture, finding the proper parameters can be time-consuming and the hardware burdensome. On the contrary, for the flow curve description the almost unused Radial Basis network offers a very easy training procedure and significantly shorter computing time under acceptable accuracy. The results of the submitted research should then serve as a background for the selection and following application of a suitable network architecture in the process of solving future flow curve description tasks.
Development of structure and properties in bimetallic Al/Cu sandwich composite during cumulative severe plastic deformation
(Sage, 2021) Kocich, Radim; Kunčická, Lenka
Development of modern materials is non-negligibly connected with enhancement of their mechanical and utility properties, which can advantageously be performed via optimized deformation processing. The study presents preparation of Al/Cu sandwich composite, reinforced with Cu-wires, by the twist channel angular pressing (TCAP) method. Extrusion of the sandwich composite via single and double pass TCAP was simulated using the finite element method, and performed experimentally. The predicted deformation behaviour was verified by 3 D Micro-CT scanning, as well as detailed microstructure observations. The results showed that already the single TCAP resulted in substantial deformation strengthening of both the component metals, and the effective strain imposed within the Al-sheath reached the value of 5 after the second pass. The Al-sheath also featured homogeneous distribution of the lowest absolute values of residual stress, and the smallest average grain size of 1.66 mu m. The Cu grains within both the composites were also significantly refined, to almost 3 mu m after the second pass. Nevertheless, the observed parameters featured slight variations across the composites' cross-sections, which can be attributed to the plastic flow behaviour phenomena. The severe imposed shear strain also resulted in increase in microhardness and imparted changes in the thermal conductivity.
Neutron diffraction study of residual stresses in a W-Ni-Co heavy alloy processed by rotary swaging at room and high temperatures
(Springer Nature, 2021) Canelo-Yubero, David; Kocich, Radim; Hervoches, Charles; Strunz, Pavel; Kunčická, Lenka; Krátká, Ludmila
Residual stresses were studied in tungsten heavy alloy bars produced by powder metallurgy and deformed by rotary swaging at room temperature (RT) and at 900 degrees C. Neutron diffraction technique was used to scan the residual stresses across the bars. Both tungsten particles and NiCo2W solid solution matrix were analysed. Maximum axial stresses of similar to 300 MPa and similar to 200 MPa were observed for the tungsten phase at the centre in the RT and in the high-temperature deformed samples, respectively. Compressive residual axial stresses were found close to the sample surface, showing that rotary swaging is a suitable deformation method for tungsten heavy alloys to provide an appropriate surface modification for its use in metallic parts undergoing, e.g., fatigue. Residual stresses developed in the NiCo2W-phase are larger than those found in the tungsten particles although with a secondary role in the overall equilibrium conditions due to its lower strength and smaller volume fraction. Total stresses for each phase were separated into macro- and microstresses. Macrostresses can be mainly influenced by the incompatibility of the elliptical cross-section of the sintered sample with the head of the rotary machine while microstresses are mainly developed by the elastic mismatch between the constituent phases.
Hot deformation activation energy of metallic materials influenced by strain value
(Polska Akademia Nauk, Instytut Metalurgii i Inżynierii Materiałowej, 2021) Schindler, Ivo; Opěla, Petr; Kawulok, Petr; Sauer, Michal; Rusz, Stanislav; Kuc, Dariusz; Rodak, Kinga
Suitable and complete sets of stress-strain curves significantly affected by dynamic recrystallization were analyzed for 11 different iron, copper, magnesium, titanium or nickel based alloys. Using the same methodology, apparent hot deformation activation energy Q(p) and Q(ss) values were calculated for each alloy based on peak stress and steady-state stress values. Linear dependence between quantities Q(p) and Q(ss) was found, while Q(p) values are on average only about 6% higher. This should not be essential in predicting true stress of a specific material depending on the temperature-compensated strain rate and strain.
Monotonic tension-torsion experiments and FE modeling on notched specimens produced by SLM technology from SS316L
(MDPI, 2021) Kořínek, Michal; Halama, Radim; Fojtík, František; Pagáč, Marek; Krček, Jiří; Krzikalla, David; Kocich, Radim; Kunčická, Lenka
The aim of this work was to monitor the mechanical behavior of 316L stainless steel produced by 3D printing in the vertical direction. The material was tested in the "as printed" state. Digital Image Correlation measurements were used for 4 types of notched specimens. The behavior of these specimens under monotonic loading was investigated in two loading paths: tension and torsion. Based on the experimental data, two yield criteria were used in the finite element analyses. Von Mises criterion and Hill criterion were applied, together with the nonlinear isotropic hardening rule of Voce. Subsequently, the load-deformation responses of simulations and experiments were compared. Results of the Hill criterion show better correlation with experimental data. The numerical study shows that taking into account the difference in yield stress in the horizontal direction of printing plays a crucial role for modeling of notched geometries loaded in the vertical direction of printing. Ductility of 3D printed specimens in the "as printed" state is also compared with 3D printed machined specimens and specimens produced by conventional methods. "As printed" specimens have 2/3 lower ductility than specimens produced by a conventional production method. Machining of "as printed" specimens does not affect the yield stress, but a significant reduction of ductility was observed due to microcracks arising from the pores as a microscopic surface study showed.
In situ neutron diffraction investigation of texture-dependent Shape Memory Effect in a near equiatomic NiTi alloy
(Elsevier, 2021) Wang, Zifan; Chen, Jingwei; Besnard, Cyril; Kunčická, Lenka; Kocich, Radim; Korsunsky, Alexander M.
To explore the possibility of customising the functional behaviour of NiTi shape memory alloy via controlling texture, binary Ni55Ti45 (wt.%) alloys were manufactured in as cast and hot swaged conditions, presenting contrasting initial texture and macroscopic performance. In situ time-of-flight neutron diffraction technique was employed to study the texture effect on the microstructural evolution during Shape Memory Effect (SME), and a range of properties were evaluated. It was found that (i) hot swaging process leads to change in grain morphology and increase in microstrain; (ii) thermal expansion coefficients of martensite and austenite variants were weakly affected by the texture and phase transformation constraint; (iii) significant texture effect on the elastic properties at both macroand micro-scale was quantified by Elasto-Plastic Self-Consistent (EPSC) modelling approach, while the anisotropic elastic moduli lie within the range of single crystal state and twinned structure; (iv) texture evolution during SME is weakly related to the initial microstructure; (v) martensite reoriented so that the <010> axis became aligned parallel to the loading direction, and retained this orientation upon unloading, revealing the underlying correlation between texture evolution and detwinning. Based on the experimental results, a multi-variant model was proposed to quantify the lattice strain evolution during SME. Validity of the conceptually simple and parametrically parsimonious model was confirmed by validation against experimental data.
Physical fundamentals of thermomechanical processing in ultrafine-grained metallic materials manufacturing
(Institute of Problems of Mechanical Engineering, 2020) Rudskoi, A. I.; Kodzhaspirov, G. E.; Kliber, Jiří; Apostolopoulos, Ch.; Kitaeva, D. A.
The processing of metallic materials through the application Thermomechanical Processing (TMP) has now become of major importance in the world research and industrial companies. A great attention is paid to study of mechanism TMP applied to different techniques and technological processes providing ultrafine-grained state of metal materials including submicro - and nanocrystalline ones. The main development in terms of obtaining bulk metallic materials received in the recent years, various schemes of TMP of metallic materials, which allows to realize the severe plastic deformation (SPD). The approach usually propose realization of large plastic strains, providing a well-developed fragmented substructure with the creation of high-angle misorientation between the fragments of the substructure. This paper discusses the physical fundamentals and various methods of thermomechanical processing, applied to single and multiphase steels and alloys ensuring the produce ultrafine-grained (UFG) metallic materials.
Effects of twist channel angular pressing on structure and properties of bimetallic Al/Cu clad composites
(Elsevier, 2020) Kocich, Radim
This study documents the effects of the twist channel angular pressing (TCAP) on the structure and selected properties of Al/Cu clad composites. Processing of the designed clad composite via single, as well as double pass TCAP was performed experimentally, and simulated via the finite element method. The deformation behaviour predicted via the simulation was verified experimentally by 3D Micro-CT scanning, and by structure analyses. The results revealed that the single pass introduced significant deformation strengthening of the Al/Cu composite components, and after the second pass, the effective imposed strain in the Al sheath approached the value of 5. The composite sheath also exhibited more or less homogeneous distribution of residual stress of the lowest observed absolute values, and the smallest observed average grain size - slightly above 1.5 μm. The Cu grains in the structures of the wires within the extruded composites also refined significantly, especially after the second pass, to almost 3 μm. However, the analysed parameters exhibited slight variations across the cross-sections of the composite billets. This can be attributed to phenomena related to the (differences in the) plastic flow. The intensive imposed shear strain also imparted increase in microhardness and changes in thermal conductivity.
The effect of predeformation on creep strength of 9% Cr steel
(MDPI, 2020) Král, Petr; Dvořák, Jiří; Blum, Wolfgang; Sklenička, Václav; Horita, Zenji; Takizawa, Yoichi; Tang, Yongpeng; Kunčická, Lenka; Kocich, Radim; Kvapilová, Marie; Svobodová, Marie
Martensitic creep-resistant P92 steel was deformed by different methods of severe plastic deformation such as rotation swaging, high-pressure sliding, and high-pressure torsion at room temperature. These methods imposed significantly different equivalent plastic strains of about 1-30. It was found that rotation swaging led to formation of heterogeneous microstructures with elongated grains where low-angle grain boundaries predominated. Other methods led to formation of ultrafine-grained (UFG) microstructures with high frequency of high-angle grain boundaries. Constant load tensile creep tests at 873 K and initial stresses in the range of 50 to 300 MPa revealed that the specimens processed by rotation swaging exhibited one order of magnitude lower minimum creep rate compared to standard P92 steel. By contrast, UFG P92 steel is significantly softer than standard P92 steel, but differences in their strengths decrease with increasing stress. Microstructural results suggest that creep behavior of P92 steel processed by severe plastic deformation is influenced by the frequency of high-angle grain boundaries and grain coarsening during creep.
Effects of austenitization temperature and pre-deformation on CCT diagrams of 23MnNiCrMo5-3 steel
(MDPI, 2020) Schindler, Ivo; Kawulok, Rostislav; Opěla, Petr; Kawulok, Petr; Rusz, Stanislav; Sojka, Jaroslav; Sauer, Michal; Navrátil, Horymír; Pindor, Lukáš
The combined effect of deformation temperature and strain value on the continuous cooling transformation (CCT) diagram of low-alloy steel with 0.23% C, 1.17% Mn, 0.79% Ni, 0.44% Cr, and 0.22% Mo was studied. The deformation temperature (identical to the austenitization temperature) was in the range suitable for the wire rolling mill. The applied compressive deformation corresponded to the true strain values in an unusually wide range. Based on the dilatometric tests and metallographic analyses, a total of five different CCT diagrams were constructed. Pre-deformation corresponding to the true strain of 0.35 or even 1.0 had no clear effect on the austenite decomposition kinetics at the austenitization temperature of 880 degrees C. During the long-lasting cooling, recrystallization and probably coarsening of the new austenitic grains occurred, which almost eliminated the influence of pre-deformation on the temperatures of the diffusion-controlled phase transformations. Decreasing the deformation temperature to 830 degrees C led to the significant acceleration of the austenite -> ferrite and austenite -> pearlite transformations due to the applied strain of 1.0 only in the region of the cooling rate between 3 and 35 degrees C center dot s(-1). The kinetics of the bainitic or martensitic transformation remained practically unaffected by the pre-deformation. The acceleration of the diffusion-controlled phase transformations resulted from the formation of an austenitic microstructure with a mean grain size of about 4 mu m. As the analysis of the stress-strain curves showed, the grain refinement was carried out by dynamic and metadynamic recrystallization. At low cooling rates, the effect of plastic deformation on the kinetics of phase transformations was indistinct.
On the Zener-Hollomon parameter, multi-layer perceptron and multivariate polynomials in the struggle for the peak and steady-state description
(MDPI, 2020) Opěla, Petr; Kawulok, Petr; Schindler, Ivo; Kawulok, Rostislav; Rusz, Stanislav; Navrátil, Horymír
Description of flow stress evolution, specifically an approximation of a set of flow curves acquired under a wide range of thermomechanical conditions, of various materials is often solved via so-called flow stress models. Some of these models are associated with a description of significant flow-curve coordinates. It is clear, the more accurate the coordinates description, the more accurate the assembled model. In the presented research, Zener-Hollomon-based relations, multi-layer perceptron networks and multivariate polynomials are employed to describe the peak and steady-state coordinates of an Invar 36 flow curve dataset. Comparison of the utilized methods in the case of the studied alloy has showed that the suitable description is given by the multivariate polynomials although the Zener-Hollomon and perceptron networks also offer valuable results.
Hot deformation behaviour of Mn-Cr-Mo low-alloy steel in various phase regions
(MDPI, 2020) Schindler, Ivo; Opěla, Petr; Kawulok, Petr; Sojka, Jaroslav; Konečná, Kateřina; Rusz, Stanislav; Kawulok, Rostislav; Sauer, Michal; Turoňová, Petra
The deformation behaviour of a coarse-grained as-cast medium-carbon steel, alloyed with 1.2% Mn, 0.8% Cr and 0.2% Mo, was studied by uniaxial compression tests for the strain rates of 0.02 s(-1)-20 s(-1)in the unusually wide range of temperatures (650-1280 degrees C), i.e., in various phase regions including the region with predominant bainite content (up to the temperature of 757 degrees C). At temperatures above 820 degrees C, the structure was fully austenitic. The hot deformation activation energies of 648 kJ center dot mol(-1)and 364 kJ center dot mol(-1)have been calculated for the temperatures <= 770 degrees C and >= 770 degrees C, respectively. This corresponds to the significant increase of flow stress in the low-temperature bainitic region. Unique information on the hot deformation behaviour of bainite was obtained. The shape of the stress-strain curves was influenced by the dynamic recrystallization of ferrite or austenite. Dynamically recrystallized austenitic grains were strongly coarsened with decreasing strain rate and growing temperature. For the austenitic region, the relationship between the peak strain and the Zener-Hollomon parameter has been derived, and the phenomenological constitutive model describing the flow stress depending on temperature, true strain rate and true strain was developed. The model can be used to predict the forming forces in the seamless tubes production of the given steel.
Deformation behavior of Al/Cu clad composite during twist channel angular pressing
(MDPI, 2020) Kocich, Radim
The research and development of modern metallic materials goes hand in hand with increasing their lifetime via optimized deformation processing. The presented work deals with preparation of an Al/Cu clad composite with implemented reinforcing Cu wires by the method of twist channel angular pressing (TCAP). Single and double pass extrusion of the clad composite was simulated numerically and carried out experimentally. This work is unique as no such study has been presented so far. Detailed monitoring of the deformation behavior during both the passes was enabled by superimposed grids and sensors. Both the sets of results revealed that already the single pass imparted significant effective strain (higher than e.g., conventional equal channel angular pressing (ECAP)), especially to the Al matrix, and resulted in notable deformation strengthening of both the Al and Cu composite components, which was confirmed by the increased punch load and decreased plastic flow velocity (second pass compared to first pass). Processing via the second pass also resulted in homogenization of the imposed strain and residual stress across the composite cross-section. However, the investigated parameters featured slight variations in dependence on the monitored location across the cross-section.
Neutron diffraction study of Ti-Zr alloy microstructure evolution during annealing after severe plastic deformation
(Springer Nature, 2020) Strunz, P.; Kunčická, Lenka; Kocich, Radim; Farkas, G.; Macháčková, Adéla; Ryukhtin, V.
The evolution of the Ti-Zr alloy microstructure (residual stresses, as well as microstress) during annealing after severe plastic deformation is reported. A strong residual macro-stresses relief starts at temperature of 530-540 degrees C. A steep decrease continues up to 580 degrees C and a further slight decrease up to 600 degrees C. Microstrain (caused by the high dislocation density created by equal channel angular pressing) is almost constant up to 300 degrees C, and then begins to decrease gradually due to recovery. The microstrain decrease accelerates at 560 degrees C and is finished at 580 degrees C. Most probably, this is caused by recrystallization. The information obtained is important for possible microstructure modifications and tuning via post-process heat treatment.
Design and optimization of induction heating for tungsten heavy alloy prior to rotary swaging
(Elsevier, 2020) Kocich, Radim
Induction heating is advantageously used in the industry to (pre)heat workpieces from ferromagnetic metallic materials. However, its application for heating of paramagnetic workpieces is still a challenge. The presented study focuses on design and optimization of induction heating for a pre-sintered WNiCo tungsten heavy alloy billet intended to be subjected to plastic deformation via warm rotary swaging. Firstly, induction heating to the initial deformation temperature of 900 degrees C is simulated via two different computational software based on the finite element method (FEM) in order to perform the best possible optimization of the heating process. Secondly, experimental induction heating is performed, prior to subsequent warm rotary swaging, to verify the designed process. Comparison of the final billet temperatures and their developments acquired via simulation and ex-periment exhibited satisfactory correlation. The study is supplemented with structure observations documenting the required heating through the WNiCo billet; the swaged structure exhibited deformed tungsten agglomerates, as well as high quality oxidation-free surface.
Correlation among the power dissipation efficiency, flow stress course, and activation energy evolution in Cr-Mo low-alloyed steel
(MDPI, 2020) Opěla, Petr; Schindler, Ivo; Kawulok, Petr; Kawulok, Rostislav; Rusz, Stanislav; Navrátil, Horymír; Jurča, Radek
In the presented research, conventional hot processing maps superimposed over the flow stress maps or activation energy maps are utilized to study a correlation among the efficiency of power dissipation, flow stress, and activation energy evolution in the case of Cr-Mo low-alloyed steel. All maps have been assembled on the basis of two flow curve datasets. The experimental one is the result of series of uniaxial hot compression tests. The predicted one has been calculated on the basis of the subsequent approximation procedure via a well-adapted artificial neural network. It was found that both flow stress and activation energy evolution are capable of expressing changes in the studied steel caused by the hot compression deformation. A direct association with the course of power dissipation efficiency is then evident in the case of both. The connection of the presence of instability districts to the activation energy evolution, flow stress course, and power dissipation efficiency was discussed further. Based on the obtained findings it can be stated that the activation energy processing maps represent another tool for the finding of appropriate forming conditions and can be utilized as a support feature for the conventionally-used processing maps to extend their informative ability.
Texture and differential stress development in W/Ni-Co composite after rotary swaging
(MDPI, 2020) Strunz, Pavel; Kocich, Radim; Canelo-Yubero, David; Macháčková, Adéla; Beran, Přemysl; Krátká, Ludmila
Knowledge of texture and residual stresses in tungsten heavy pseudoalloys is substantial for the microstructure optimization. These characteristics were determined in cold and warm rotary swaged W/NiCo composite with help of neutron diffraction. The results were discussed in view of the observed microstructure and mechanical properties. The investigated bars consisted of tungsten agglomerates (bcc lattice) surrounded by NiCo-based matrix (fcc lattice). No preferential crystallographic orientation was found in the as-sintered bar. A strong texture was formed in both the tungsten agglomerates ( fiber texture parallel to the swaging axis) and in the NiCo-based matrix ( fiber texture) after rotary swaging. Although usually of double-fiber texture, the fiber of the fcc structures was nearly missing in the matrix. Further, the cold-swaged bar exhibited substantially stronger texture for both phases which corresponds to the higher measured ultimate tensile strength. The residual stress differences were employed for characterization of the stress state of the bars. The largest residual stress difference (approximate to 400 MPa) was found at the center of the bar deformed at room temperature. The hoop stresses were non-symmetrical with respect to the swaging axis, which was likely caused by the elliptical cross section of the as-sintered bar.
Effects of sintering conditions on structures and properties of sintered tungsten heavy alloy
(MDPI, 2020) Kunčická, Lenka; Kocich, Radim; Klečková, Zuzana
Probably the most advantageous fabrication technology of tungsten heavy alloys enabling the achievement of required performance combines methods of powder metallurgy and processing by intensive plastic deformation. Since the selected processing conditions applied for each individual processing step affect the final structures and properties of the alloys, their optimization is of the utmost importance. This study deals with thorough investigations of the effects of sintering temperature, sintering time, and subsequent quenching in water on the structures and mechanical properties of a 93W6Ni1Co tungsten heavy alloy. The results showed that sintering at temperatures of or above 1525 degrees C leads to formation of structures featuring W agglomerates surrounded by the NiCo matrix. The sintering time has non-negligible effects on the microhardness of the sintered samples as it affects the diffusion and structure softening phenomena. Implementation of quenching to the processing technology results in excellent plasticity of the green sintered and quenched pieces of almost 20%, while maintaining the strength of more than 1000 MPa.

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