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Mechanical Properties in Progressive Mechanically Processed Metallic Materials
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Mechanical Properties in Progressive Mechanically Processed Metallic Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (31 August 2020) | Viewed by 37299

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Dr. Radim Kocich

E-Mail Website
Guest Editor
Regional Materials Technology and Science Centre (RMTSC), Faculty of Materials Science and Technology, VŠB—Technical University of Ostrava, Ostrava, Czech Republic
Interests: materials forming; severe plastic deformation; non-ferrous metals; composites; thermomechanical processing; numerical simulations
Special Issues, Collections and Topics in MDPI journals
Dr. Lenka Kunčická

E-Mail Website
Guest Editor
Institut of Physics of Materials, Czech Academy of Sciences, Brno, Czech Republic
Interests: thermo-mechanical treatment; non-ferrous metals; structure and stress analyses; numerical methods
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The demands on innovative materials given by the ever-increasing requirements of contemporary industry impart the usage of high-performance engineering materials based on steel and other nonferrous metals and alloys, with multicomponent materials, such as gradient structures and composites, which are able to satisfy top-level individual demands, having been favored in recent years. Among the essential features of progressive metallic materials used for modern applications are enhanced mechanical properties, but also other high-level functional characteristics, such as thermal–physical parameters, corrosion rate, and electric resistance. The properties of materials and alloys ensue from their structures, which can primarily be affected by the preparation/production process. However, the production of materials featuring high levels of the required properties without the necessity to use costly alloying elements or time- and money-demanding heat treatment technologies typically used to enhance the mechanical properties of metallic materials (especially specific strength) still remains a challenge.

One of the possible ways to effectively increase the utility properties of metallic materials is to decrease their grain size. The introduction of thermomechanical treatment represented a breakthrough in grain refinement, consequently leading to significant improvement of the mechanical properties of metallic materials. Contrary to conventional production technologies, the main advantage of such treatment is the possibility to precisely control structural phenomena, including grain size, substructure development, texture, and volumes and types of grains boundaries, all of which affect the final mechanical and utility properties. Especially grain boundaries essentially affect the formability and strengthening ability of polycrystalline materials, despite being imperfections in materials’ structures. Grain boundaries can significantly contribute to material strengthening; however, the final effect depends on the ratio of grain boundaries and grain interiors.

Thermomechanical treatment can only decrease the grain size to the scale of microns. However, further research devoted to pushing materials’ performance beyond the limits led to the introduction of severe plastic deformation (SPD) methods providing producers with the ability to acquire ultra-fine-grained and nanoscaled metallic materials with superior mechanical properties. SPD methods can be performed with the help of conventional forming equipment; however, many newly designed processes have been introduced.

It is my pleasure to invite you to submit a manuscript for this Special Issue. Full papers, communications, and reviews are all welcome.

Assoc. Prof. Radim Kocich
Dr. Lenka Kunčická
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Mechanical properties
  • Functional properties
  • Metallic systems
  • Mechanical processing
  • Structural phenomena

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

3 pages, 172 KiB  
Editorial
Special Issue: Mechanical Properties in Progressive Mechanically Processed Metallic Materials
by Radim Kocich and Lenka Kunčická
Materials 2020, 13(20), 4668; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13204668 - 20 Oct 2020
Cited by 1 | Viewed by 1571
Abstract
The research and development of modern metallic materials imparts not only the introduction of innovative alloys and compounds, but also the increasing lifetime of existing materials via optimized deformation processing. Among the essential features of progressive metallic materials used for modern applications are [...] Read more.
The research and development of modern metallic materials imparts not only the introduction of innovative alloys and compounds, but also the increasing lifetime of existing materials via optimized deformation processing. Among the essential features of progressive metallic materials used for modern applications are enhanced mechanical properties, but also other high-level functional characteristics, such as thermal–physical parameters, corrosion rate, and electric resistance. The properties of materials and alloys ensue from their structures, which can primarily be affected by the preparation/production process. The Special Issue “Mechanical Properties in Progressive Mechanically Processed Metallic Materials” was established to present recent developments and innovations particularly in the engineering field. The Special Issue comprises papers dealing with modern materials, such as metallic composites and pseudoalloys, as well as developments in various processing technologies. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)

Research

Jump to: Editorial, Review

17 pages, 21127 KiB  
Communication
Influence of Steel Structure on Machinability by Abrasive Water Jet
by Irena M. Hlaváčová, Marek Sadílek, Petra Váňová, Štefan Szumilo and Martin Tyč
Materials 2020, 13(19), 4424; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13194424 - 05 Oct 2020
Cited by 17 | Viewed by 3309
Abstract
Although the abrasive waterjet (AWJ) has been widely used for steel cutting for decades and there are hundreds of research papers or even books dealing with this technology, relatively little is known about the relation between the steel microstructure and the AWJ cutting [...] Read more.
Although the abrasive waterjet (AWJ) has been widely used for steel cutting for decades and there are hundreds of research papers or even books dealing with this technology, relatively little is known about the relation between the steel microstructure and the AWJ cutting efficiency. The steel microstructure can be significantly affected by heat treatment. Three different steel grades, carbon steel C45, micro-alloyed steel 37MnSi5 and low-alloy steel 30CrV9, were subjected to four different types of heat treatment: normalization annealing, soft annealing, quenching and quenching followed by tempering. Then, they were cut by an abrasive water jet, while identical cutting parameters were applied. The relations between the mechanical characteristics of heat-treated steels and the surface roughness parameters Ra, Rz and RSm were studied. A comparison of changes in the surface roughness parameters and Young modulus variation led to the conclusion that the modulus was not significantly responsible for the surface roughness. The changes of RSm did not prove any correlation to either the mechanical characteristics or the visible microstructure dimensions. The homogeneity of the steel microstructure appeared to be the most important factor for the cutting quality; the higher the difference in the hardness of the structural components in the inhomogeneous microstructure was, the higher were the roughness values. A more complex measurement and critical evaluation of the declination angle measurement compared to the surface roughness measurement are planned in future research. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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18 pages, 10834 KiB  
Article
Study on Strengthening Mechanism of 9Cr-1.5Mo-1Co and 9Cr-3W-3Co Heat Resistant Steels
by Long Zhao, Xiangru Chen, Tieming Wu and Qijie Zhai
Materials 2020, 13(19), 4340; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13194340 - 29 Sep 2020
Cited by 6 | Viewed by 1781
Abstract
The strengthening mechanism of 9Cr–1.5Mo–1Co and 9Cr–3W–3Co heat resistant steel was studied by tensile test and microstructure analysis. At the same temperature, the yield strength of 9Cr–3W–3Co heat-resistant steel is higher than that of 9Cr–1.5Mo–1Co heat-resistant steel. Microstructure analysis proved that the strength [...] Read more.
The strengthening mechanism of 9Cr–1.5Mo–1Co and 9Cr–3W–3Co heat resistant steel was studied by tensile test and microstructure analysis. At the same temperature, the yield strength of 9Cr–3W–3Co heat-resistant steel is higher than that of 9Cr–1.5Mo–1Co heat-resistant steel. Microstructure analysis proved that the strength of 9Cr–1.5Mo–1Co and 9Cr–3W–3Co heat-resistant steel is affected by grain boundary, dislocation, precipitation, and solid solution atoms. The excellent high temperature mechanical properties of 9Cr–3W–3Co heat-resistant steel are mainly due to the solution strengthening caused by Co and W atoms and the high-density dislocations distributed in the matrix; however, 9Cr–1.5Mo–1Co heat-resistant steel is mainly due to the martensitic lath and precipitation strengthening. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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15 pages, 5274 KiB  
Article
Structure Characteristics Affected by Material Plastic Flow in Twist Channel Angular Pressed Al/Cu Clad Composites
by Lenka Kunčická and Zuzana Klečková
Materials 2020, 13(18), 4161; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13184161 - 18 Sep 2020
Cited by 4 | Viewed by 1697
Abstract
The study focuses on structure analyses, texture analyses in particular, of an Al/Cu clad composite manufactured by single and double pass of the twist channel angular pressing (TCAP) method. Microscopic analyses were supplemented with numerical predictions focused on the effective imposed strain and [...] Read more.
The study focuses on structure analyses, texture analyses in particular, of an Al/Cu clad composite manufactured by single and double pass of the twist channel angular pressing (TCAP) method. Microscopic analyses were supplemented with numerical predictions focused on the effective imposed strain and material plastic flow, and microhardness measurements. Both the TCAP passes imparted characteristic texture orientations to the reinforcing Cu wires, however, the individual preferential grains’ orientations throughout the composite differed and depended on the location of the particular wire within the Al sheath during extrusion, i.e., on the dominant acting strain path. The second TCAP pass resulted in texture homogenization; all the Cu wires finally exhibited dominant A fiber shear texture. This finding was in accordance with the homogenization of the imposed strain predicted after the second TCAP pass. The results also revealed that both the component metals exhibited significant deformation strengthening (which also caused bending of the ends of the Cu wires within the Al sheath after extrusion). The average microhardness of the Cu wires after the second pass reached up to 128 HV, while for the Al sheath the value was 86 HV. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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14 pages, 3201 KiB  
Article
Deformation Behavior of Al/Cu Clad Composite During Twist Channel Angular Pressing
by Radim Kocich
Materials 2020, 13(18), 4047; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13184047 - 11 Sep 2020
Cited by 6 | Viewed by 1668
Abstract
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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15 pages, 3752 KiB  
Article
Influence of Material Structure on Forces Measured during Abrasive Waterjet (AWJ) Machining
by Libor M. Hlaváč, Adam Štefek, Martin Tyč and Daniel Krajcarz
Materials 2020, 13(17), 3878; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173878 - 02 Sep 2020
Cited by 10 | Viewed by 2143
Abstract
Material structure is one of the important factors influencing abrasive waterjet (AWJ) machining efficiency and quality. The force measurements were performed on samples prepared from two very similar steels with different thicknesses and heat treatment. The samples were austenitized at 850 °C, quenched [...] Read more.
Material structure is one of the important factors influencing abrasive waterjet (AWJ) machining efficiency and quality. The force measurements were performed on samples prepared from two very similar steels with different thicknesses and heat treatment. The samples were austenitized at 850 °C, quenched in polymer and tempered at various temperatures between 20 °C and 640 °C. The resulting states of material substantially differed in strength and hardness. Therefore, samples prepared from these material states are ideal for testing of material response to AWJ. The force measurements were chosen to test the possible influence of material structure on the material response to the AWJ impact. The results show that differences in material structure and respective material properties influence the limit traverse speed. The cutting to deformation force ratio seems to be a function of relative traverse speed independently on material structure. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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11 pages, 4930 KiB  
Article
Effects of Sintering Conditions on Structures and Properties of Sintered Tungsten Heavy Alloy
by Lenka Kunčická, Radim Kocich and Zuzana Klečková
Materials 2020, 13(10), 2338; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13102338 - 19 May 2020
Cited by 13 | Viewed by 2627
Abstract
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 [...] Read more.
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 °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. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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12 pages, 4775 KiB  
Article
Effect of Imposed Shear Strain on Steel Ring Surfaces during Milling in High-Speed Disintegrator
by Karel Dvořák, Adéla Macháčková, Simona Ravaszová and Dominik Gazdič
Materials 2020, 13(10), 2234; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13102234 - 13 May 2020
Cited by 4 | Viewed by 1736
Abstract
This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive [...] Read more.
This contribution characterizes the performance of a DESI 11 high-speed disintegrator working on the principle of a pin mill with two opposite counter-rotating rotors. As the ground material, batches of Portland cement featuring 6–7 Mohs scale hardness and containing relatively hard and abrasive compounds with the specific surface areas ranging from 200 to 500 m2/kg, with the step of 50 m2/kg, were used. The character of the ground particles was assessed via scanning electron microscopy and measurement of the absolute/relative increase in their specific surface areas. Detailed characterization of the rotors was performed via recording the thermal imprints, evaluating their wear by 3D optical microscopy, and measuring rotor weight loss after the grinding of constant amounts of cement. The results showed that coarse particles are ground by impacting the front faces of the pins, while finer particles are primarily milled via mutual collisions. Therefore, the coarse particles cause higher abrasion and wear on the rotor pins; after the milling of 20 kg of the 200 m2/kg cement sample, the wear of the rotor reached up to 5% of its original mass and the pins were severely damaged. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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15 pages, 3605 KiB  
Article
Correlating Microstrain and Activated Slip Systems with Mechanical Properties within Rotary Swaged WNiCo Pseudoalloy
by Pavel Strunz, Lenka Kunčická, Přemysl Beran, Radim Kocich and Charles Hervoches
Materials 2020, 13(1), 208; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13010208 - 03 Jan 2020
Cited by 14 | Viewed by 2555
Abstract
Due to their superb mechanical properties and high specific mass, tungsten heavy alloys are used in demanding applications, such as kinetic penetrators, gyroscope rotors, or radiation shielding. However, their structure, consisting of hard tungsten particles embedded in a soft matrix, makes the deformation [...] Read more.
Due to their superb mechanical properties and high specific mass, tungsten heavy alloys are used in demanding applications, such as kinetic penetrators, gyroscope rotors, or radiation shielding. However, their structure, consisting of hard tungsten particles embedded in a soft matrix, makes the deformation processing a challenging task. This study focused on the characterization of deformation behavior during thermomechanical processing of a WNiCo tungsten heavy alloy (THA) via the method of rotary swaging at various temperatures. Emphasis is given to microstrain development and determination of the activated slip systems and dislocation density via neutron diffraction. The analyses showed that the grains of the NiCo2W matrix refined significantly after the deformation treatments. The microstrain was higher in the cold swaged sample (44.2 × 10−4). Both the samples swaged at 20 °C and 900 °C exhibited the activation of edge dislocations with <111> {110} or <110> {111} slip systems, and/or screw dislocations with <110> slip system in the NiCo2W matrix. Dislocation densities were determined and the results were correlated with the final mechanical properties of the swaged bars. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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Graphical abstract

28 pages, 11637 KiB  
Article
Strain Range Dependent Cyclic Hardening of 08Ch18N10T Stainless Steel—Experiments and Simulations
by Jaromír Fumfera, Radim Halama, Radek Procházka, Petr Gál and Miroslav Španiel
Materials 2019, 12(24), 4243; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12244243 - 17 Dec 2019
Cited by 2 | Viewed by 2484
Abstract
This paper describes and presents an experimental program of low-cycle fatigue tests of austenitic stainless steel 08Ch18N10T at room temperature. The low-cycle tests include uniaxial and torsional tests for various specimen geometries and for a vast range of strain amplitude. The experimental data [...] Read more.
This paper describes and presents an experimental program of low-cycle fatigue tests of austenitic stainless steel 08Ch18N10T at room temperature. The low-cycle tests include uniaxial and torsional tests for various specimen geometries and for a vast range of strain amplitude. The experimental data was used to validate the proposed cyclic plasticity model for predicting the strain-range dependent behavior of austenitic steels. The proposed model uses a virtual back-stress variable corresponding to a cyclically stable material under strain control. This internal variable is defined by means of a memory surface introduced in the stress space. The linear isotropic hardening rule is also superposed. A modification is presented that enables the cyclic hardening response of 08Ch18N10T to be simulated correctly under torsional loading conditions. A comparison is made between the real experimental results and the numerical simulation results, demonstrating the robustness of the proposed cyclic plasticity model. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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14 pages, 4630 KiB  
Article
Affecting Structure Characteristics of Rotary Swaged Tungsten Heavy Alloy Via Variable Deformation Temperature
by Adéla Macháčková, Ludmila Krátká, Rudolf Petrmichl, Lenka Kunčická and Radim Kocich
Materials 2019, 12(24), 4200; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12244200 - 13 Dec 2019
Cited by 30 | Viewed by 2412
Abstract
This study focuses on numerical prediction and experimental investigation of deformation behaviour of a tungsten heavy alloy prepared via powder metallurgy and subsequent cold (20 °C) and warm (900 °C) rotary swaging. Special emphasis was placed on the prediction of the effects of [...] Read more.
This study focuses on numerical prediction and experimental investigation of deformation behaviour of a tungsten heavy alloy prepared via powder metallurgy and subsequent cold (20 °C) and warm (900 °C) rotary swaging. Special emphasis was placed on the prediction of the effects of the applied induction heating. As shown by the results, the predicted material behaviour was in good correlation with the real experiment. The differences in the plastic flow during cold and warm swaging imparted differences in structural development and the occurrence of residual stress. Both the swaged pieces exhibited the presence of residual stress in the peripheries of W agglomerates. However, the NiCO matrix of the warm-swaged piece also exhibited the presence of residual stress, and it also featured regions with increased W content. Testing of mechanical properties revealed the ultimate tensile strength of the swaged pieces to be approximately twice as high as of the sintered piece (860 MPa compared to 1650 MPa and 1828 MPa after warm and cold swaging, respectively). Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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17 pages, 4392 KiB  
Article
Assessment of Retained Austenite in Fine Grained Inductive Heat Treated Spring Steel
by Anna Olina, Miroslav Píška, Martin Petrenec, Charles Hervoches, Přemysl Beran, Jiří Pechoušek and Petr Král
Materials 2019, 12(24), 4063; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12244063 - 05 Dec 2019
Cited by 4 | Viewed by 2707
Abstract
Advanced thermomechanical hot rolling is becoming a widely used technology for the production of fine-grained spring steel. Different rapid phase transformations during the inductive heat treatment of such steel causes the inhomogeneous mixture of martensitic, bainitic, and austenitic phases that affects the service [...] Read more.
Advanced thermomechanical hot rolling is becoming a widely used technology for the production of fine-grained spring steel. Different rapid phase transformations during the inductive heat treatment of such steel causes the inhomogeneous mixture of martensitic, bainitic, and austenitic phases that affects the service properties of the steel. An important task is to assess the amount of retained austenite and its distribution over the cross-section of the inductive quenched and tempered wire in order to evaluate the mechanical properties of the material. Three different analytical methods were used for the comparative quantitative assessment of the amount of retained austenite in both the core and rim areas of the sample cross-section: neutron diffraction—for the bulk of the material, Mössbauer spectroscopy—for measurement in a surface layer, and the metallographic investigations carried by the EBSD. The methods confirmed the excessive amount of retained austenite in the core area that could negatively affect the plasticity of the material. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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15 pages, 8599 KiB  
Article
The Effect of Processing Route on Properties of HfNbTaTiZr High Entropy Alloy
by Jaroslav Málek, Jiří Zýka, František Lukáč, Monika Vilémová, Tomáš Vlasák, Jakub Čížek, Oksana Melikhova, Adéla Macháčková and Hyoung-Seop Kim
Materials 2019, 12(23), 4022; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12234022 - 03 Dec 2019
Cited by 21 | Viewed by 4467
Abstract
High entropy alloys (HEA) have been one of the most attractive groups of materials for researchers in the last several years. Since HEAs are potential candidates for many (e.g., refractory, cryogenic, medical) applications, their properties are studied intensively. The most frequent method of [...] Read more.
High entropy alloys (HEA) have been one of the most attractive groups of materials for researchers in the last several years. Since HEAs are potential candidates for many (e.g., refractory, cryogenic, medical) applications, their properties are studied intensively. The most frequent method of HEA synthesis is arc or induction melting. Powder metallurgy is a perspective technique of alloy synthesis and therefore in this work the possibilities of synthesis of HfNbTaTiZr HEA from powders were studied. Blended elemental powders were sintered, hot isostatically pressed, and subsequently swaged using a special technique of swaging where the sample is enveloped by a titanium alloy. This method does not result in a full density alloy due to cracking during swaging. Spark plasma sintering (SPS) of mechanically alloyed powders resulted in a fully dense but brittle specimen. The most promising result was obtained by SPS treatment of gas atomized powder with low oxygen content. The microstructure of HfNbTaTiZr specimen prepared this way can be refined by high pressure torsion deformation resulting in a high hardness of 410 HV10 and very fine microstructure with grain size well below 500 nm. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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23 pages, 10792 KiB  
Article
Fatigue Life of 7475-T7351 Aluminum After Local Severe Plastic Deformation Caused by Machining
by Petra Ohnistova, Miroslav Piska, Martin Petrenec, Jiri Dluhos, Jana Hornikova and Pavel Sandera
Materials 2019, 12(21), 3605; https://0-doi-org.brum.beds.ac.uk/10.3390/ma12213605 - 03 Nov 2019
Cited by 9 | Viewed by 3096
Abstract
The fatigue properties of thermo-mechanically treated and machined aluminum alloy 7475-T7351 have been studied. The applied advanced machining strategy induced intensive plastic deformation on the machined surface under defined cutting conditions. Therefore, a detailed study of 3D surface topography was performed. Advanced characterization [...] Read more.
The fatigue properties of thermo-mechanically treated and machined aluminum alloy 7475-T7351 have been studied. The applied advanced machining strategy induced intensive plastic deformation on the machined surface under defined cutting conditions. Therefore, a detailed study of 3D surface topography was performed. Advanced characterization of the material structure and electron back scattered diffraction mapping of selected chemical phases were performed, as well as energy dispersive X-ray analysis of the surface. Advanced mechanical properties of the material were investigated in situ with a scanning electron microscope that was equipped with a unique tensile fixture. The fatigue results confirmed an evident dispersion of the data, but the mechanism of crack nucleation was established. Fracture surface analysis showed that the cracks nucleated at the brittle secondary particles dispersed in the material matrix. The surface topography of samples that had been machined in wide range of cutting/deformation conditions by milling has not proved to be a decisive factor in terms of the fatigue behavior. The incoherent interface and decohesion between the alumina matrix and the brittle secondary phases proved to significantly affect the ultimate strength of the material. Tool engagement also affected the fatigue resistance of the material. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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Review

Jump to: Editorial, Research

19 pages, 2444 KiB  
Review
Decade of Twist Channel Angular Pressing: A Review
by Adéla Macháčková
Materials 2020, 13(7), 1725; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13071725 - 07 Apr 2020
Cited by 11 | Viewed by 2200
Abstract
The methods of severe plastic deformation (SPD) have gained attention within the last decades primarily owing to their ability to substantially refine the grains within metallic materials and, therefore, significantly enhance the properties. Among one of the most efficient SPD methods is the [...] Read more.
The methods of severe plastic deformation (SPD) have gained attention within the last decades primarily owing to their ability to substantially refine the grains within metallic materials and, therefore, significantly enhance the properties. Among one of the most efficient SPD methods is the equal channel angular pressing (ECAP)-based twist channel angular pressing (TCAP) method, combining channel twist and channel bending within a single die. This unique die affects the processed material with three independent strain paths during a single pass, which supports the development of substructure and efficiently refines the grains. This review is intended to summarize the characteristics of the TCAP method and its main features documented within the last decade, since its development in 2010. The article is supplemented with a brief characterization of other known SPD methods based on the combination of ECAP and twist extrusion (TE) within a single die. Full article
(This article belongs to the Special Issue Mechanical Properties in Progressive Mechanically Processed Metallic Materials)
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