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1

Finite element analysis of material deformation behaviour during DRECE: the sheet metal SPD process

Tkocz Marek, Kowalczyk Karolina, Bulzak Tomasz, Jabłońska Magdalena B., Hawryluk Marek

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e145, 2023

EN

The material deformation behaviour during the innovative SPD process called DRECE (Dual Rolls Equal Channel Extrusion) has been analysed by FEM simulations. In the process, a workpiece in the form of a strip is subjected to plastic deformation by passing through the angular channel; however, the workpiece dimensions remain the same after a pass is finished. Performing consecutive passes allow for increasing the effective strain in the material to a required level. In the conducted simulations two various channel angles (108° and 113°) have been taken into consideration, as well as two processing routes, A and C (without and with turning the strip upside-down between consecutive passes, respectively). The analysis of simulation results has revealed that significant strain and stress inhomogeneities across the strip thickness are generated in a single DRECE pass. The die design (the inner and outer corner radius) and friction conditions affect the material flow, reducing significantly the shear strain in the near-surface regions of the strip. The strain inhomogeneity can be effectively reduced by choosing the processing route C. The strain distributions and the corresponding tensile test results have confirmed that the smaller channel die angle allows to generate larger strain and higher strength of the strip but also reduces its ductility more than the die setup with the larger channel die angle.

2

Effect of Machining Process Parameters and Number of Pass on Compaction Behaviour of Commercially Pure Aluminium Chips Consolidated by Equal Channel Angular Pressing (ECAP) Using Response Surface Methodology

Palanivel Ramaswamy, Vigneshwaran S., Alshqirate Abedalrzaq, Madhavan R., Venkatachalam P., Laubscher R. F.

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 1

357--370

EN

This work investigates the compaction behaviour of commercial pure aluminium chips (CP Al) produced during a machining operation and subsequently consolidated by Equal Channel Angular Pressing (ECAP). Empirical models were developed to describe the relative density and hardness of the compacted product of ECAP as functions of the initial machining input parameters including cutting edge angle (CA), depth of cut (DOC) and then the number of consolidation pass during ECAP. The models were developed utilizing response surface methodology (RSM) based on data from a central composite face centred factorial design of experiments approach. The models were then validated by using Analysis of Variance (ANOVA). The effect of input parameters on the relative density and hardness of the ECAP consolidated samples are presented and discussed including details as regards to the mechanical and microstructural properties. An optimum set of input parameters are identified and presented where the best relative density and hardness are demonstrated.

3

Texture evolution of magnesium alloy AZ31B subjected to severe plastic deformation

Frydrych Karol

Engineering Transactions

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2021

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Vol. 69, iss. 4

337--352

EN

The paper presents the simulations of texture evolution of the AZ31B Mg alloy subjected to equal channel angular pressing (ECAP) and rotary swaging (RS) processes. It is shown that using the crystal plasticity (CP) parameters obtained by curve fitting conducted on simple mechanical tests with the aid of the evolutionary algorithm, it is possible to correctly predict the texture evolution in both processes. The influence of the initial texture as well as the CP parameters is discussed.

4

On rough set theory on achieving high quality cable material production by green low carbon technology

Shuai Guoliang, Li Zhen, Zhang Diantao, Elhefnawey Maged, Li Li

Ecological Chemistry and Engineering. S

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2021

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Vol. 28, nr 1

49--59

EN

As the second largest machinery industry, the energy-intensive cable industry not only creates a lot of economic value but also consumes a lot of energy. It is an inevitable requirement to promote the technological development of the industry in the new era to improve the quality and efficiency and realise industrial energy-saving and consumption reduction. In order to obtain good strength and conductivity, the metal rods of cable are usually heat-treated for several hours or even several days after the rods are extruded, this is a major energy consuming process in traditional production. Based on the background, this study adopted the energy-saving equal-channel angular pressing (ECAP) technology to replace the traditional heating treatment process, and converted the simple heat conduction with thermo-mechanical energy transfer, so as to realise the good strength and conductivity matching of the cable aluminum alloy material. In this study, energy-saving ECAP technology is used to replace the traditional heat treatment process, and heat-mechanical energy transfer is used to replace the simple heat conduction, so as to achieve good strength and conductivity matching of cable aluminium alloy material. The results show that the suitable ECAP process routes can improve the microstructure of aluminum alloy with higher strength and conductivity than the traditional heating process. The research results can be used for technology upgrading and low carbon production in cable industry due to the significantly time reduction of the energy-consuming heat treatment and the high-efficient obtainment of high-quality production.

5

Investigation of Strain Inhomogeneity in Hexa-ECAP Processed AA7075

Öğüt Serkan, Kaya Hasan, Kentli Aykut, Özbeyaz Kerim, Şahbaz Mehmet, Uçar Mehmet

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 2

431--436

EN

Severe Plastic Deformation (SPD) techniques have been used by researchers for last three decades in order to obtain Ultra-Fine Grained (UFG) materials. Equal Channel Angular Pressing (ECAP) is preferred more than other SPD techniques thanks to its high performance and practicability. Hexa Equal Channel Angular Pressing (Hexa-ECAP) – modified ECAP technique which enables to apply ECAP routes for cylindrical samples properly – was preferred in this study. Within the objective of this study, the effects of coefficient and ram velocity on the mean effective strain and strain inhomogeneity of Hexa-ECAP processed Al7075 aluminium alloy were investigated. Also, the effects of ram velocity and friction coefficient on hardness homogeneity were investigated benefitting from the similarity between the hardness distribution and the strain distribution.

6

Solid-state welding of ultrafine grained copper rods

Morawiński Łukasz, Jasiński Cezary, Ciemiorek Marta, Chmielewski Tomasz, Olejnik Lech, Lewandowska Małgorzata

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

31--43

EN

The article focuses on the Direct Drive Rotary Friction Welding of ultrafine-grained copper rods, which feature increased mechanical properties and good electrical properties, yet are limited in size. The use of UFG metals is often limited by the too small dimensions of semi-finished elements produced by SPD methods. Therefore, the production of finished machine parts from UFG metals is currently economically unjustified. Dismissal of dimensional limitations can be done by introducing joining to technological processes. The proposed joining method does not lead to a melting of the material in the joining zone or excessive degradation of the UFG microstructure. To obtain the best results, the research used the method of low-energy welding of two kinds of specimens: with a flat or a conical contact surface. In the article, the authors present, by means of metallographic microsections and microhardness measurements, the influence of rotational speed, welding pressure and conical shape contact surface on the quality of the obtained joints. The conducted research made it possible to obtain good quality joints whose microhardness is reduced only by about 10% in comparison with the base material and the tensile strength dropped from only 397–358 MPa.

7

Microstructure and strengthening model of Al-3%Mg alloy in a heat treated state subjected to ECAP process

Snopiński P.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 90, nr 1

5--10

EN

Purpose: The aim of this paper is to investigate the microstructure evolution of a heat treated Al-3%Mg aluminium alloy subjected to the ECAP (equal channel angular pressing process). Design/methodology/approach: Commercial Al-3%Mg alloy subjected to the solution treatment followed by an artificial aging was subjected to the 6 ECAP passes using a processing route Bc. Then the microstructure investigations using a light microscopy, scanning electron microscopy and transmission electron microscopy were carried out. Additionally the XRD technique was used to calculate lattice micro strain and dislocation density. Findings: The experimental results showed that the obtained microstructure is refined by mutual interactions of shear and microshear bands. The TEM investigation revealed typical for deformed aluminium alloys structure constituents such as dislocation-free grains, nonequilibrium grain boundaries, dislocation cell and (sub)grain structures. Research limitations/implications: The presented investigation results were carried out on samples, not on final products. Practical implications: Current research is moving towards to develop high strength material having a ultra-fine grained microstructure and increased mechanical strength. Originality/value: The paper focuses on the microstructure characterization of ECAP processed Al-3%Mg aluminium alloy. The relationship between the obtained microstructure and its contribution to the Yield strength is investigated.

8

Effect of SPD processing on the structure and properties of Al–Mg alloy

Snopiński P., Tański T., Król M.

Inżynieria Materiałowa

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2018

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Vol. 39, nr 1

2--7

EN

Severe plastic deformation processes are one of the most promising methods for mechanical properties improvement through the grain refinement and strain accumulation. In the recent years, there is considerable interest in the application of the Equal Channel Angular Pressing method that is an effective tool for attaining ultrafine grain sizes in polycrystalline materials. A significant advantage of this method in comparison to conventional metalworking processes, such as extrusion and rolling, is that very high strains may be attained without any change in the cross-sectional dimensions of the sample. However, metalworking process of aluminium alloys may be complicated because of the alloying additions. It is known that aluminum–magnesium alloys are hardly deformable because the addition of Mg decreases workability. Thus there is a need to investigate the effect of the combination of heat treatment with SPD to simultaneously increase the workability and mechanical properties through the grain refinement. The research aimed to study the microstructure evolution of the AlMg5 alloy subjected to the heat treatment, ECAP and post-ECAP annealing. Microhardness measurements and tensile tests were undertaken to determine the mechanical properties of the AlMg5 alloy in different states. The results obtained show the relationship between the microstructure and the mechanical properties of the material.

PL

Głównym celem zrealizowanych badań była analiza mechanizmów umocnienia oraz dobór optymalnych warunków technologicznych wpływających na polepszenie: podatności na przeróbkę plastyczną oraz właściwości mechanicznych trudno odkształcalnego stopu aluminium o 5% zawartości magnezu, który poddano intensywnemu odkształceniu plastycznemu z wykorzystaniem metody przeciskania przez kanał kątowy (ECAP). Zwiększanie się liczby defektów struktury w materiałach metalowych skutkuje wzrostem wytrzymałości, jednocześnie pogorszając plastyczność, dlatego wykorzystując tradycyjną obróbkę cieplną w połączeniu z technologiami intensywnego odkształcenia plastycznego, uzyskano materiał o zbalansowanej kombinacji obu właściwości. Jedną z zastosowanych technik pozwalających na poprawę właściwości plastycznych materiałów ultradrobnoziarnistych było wytworzenie struktury bimodalnej zapewniającej zbalansowaną kombinację właściwości — dużą wytrzymałość i lepszą plastyczność.

9

Microhardness Evolution in Relation to the Crystalline Microstructure of Aluminum Alloy AA3004

Izairi N., Ajredini F., Vevecka-Pfiftaj A., Makreski P., Ristova M. M.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 3

1101--1108

EN

Equal-channel angular pressing (ECAP) was used as a technique for severe plastic deformation (SPD) on Al alloy AA3004. This technique produced fully dense materials of refined grain structure to sub-micrometer dimensions and advanced mechanical properties. The ECAP processing of samples was conducted as 1 to 4 passes through the die at room temperature. We present the results of the studied homogeneity evolution with the ECAP treatment. Furthermore, a Scanning Electron Microscope (SEM) was used for examination of the microstructure changes in samples undergone from 1 to 4 passes. The microhardness-HV increased upon each ECAP pass. The resulting micro-hardness evolution was attributed to crystalline microstructure modifications, such as the d-spacing (studied by X-ray Diffraction-XRD) depending on the number of ECAP pressings. The microcrystalline changes (grain refining evaluated from the Scanning Electron Microscopy - SEM images) were found to be related to the HV, following the Hall-Petch equation.

10

Intensywne odkształcenie plastyczne metali nieżelaznych

Tański T., Snopiński P.

LAB Laboratoria, Aparatura, Badania

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2017

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R. 22, nr 4

30--34

11

Thermal Stability of AA1050 Aluminum Alloy after Equal Channel Angular Pressing

Koprowski P., Bogucki R., Bieda M., Kawałko J., Sztwiertnia K.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 2A

777--786

EN

The annealing behavior of AA1050 aluminum alloy deformed by equal-channel angular pressing (ECAP) was studied experimentally. The material was subjected to extrusion through die with channels intersecting at an 90° angle. Samples were pressed for up to 8 passes using route BC, then cut into slices and subsequently annealed for 1 hour at temperatures from 100°C to 350°C. Hardness measurements were performed on each slice. Microstructure of material was analyzed in the longitudinal section by means of Electron Backscatter Diffraction system in a scanning electron microscope (EBSD/SEM). From the obtained sets of Kikuchi diffraction patterns orientation maps and Image Quality maps were determined. Grain size, disorientation distributions and crystallographic texture were also estimated. ECAP caused significant improvement of hardness, with stabilization after 4 passes. Refinement of microstructure was obtained with the increasing amount of passes. Material properties were stable during annealing at temperatures lower than 150°C. Annealing at higher temperatures caused a decrease in hardness corresponding to an increase of the grain size.

12

Microstructure and Properties of Selected Magnesium-Aluminum Alloys Prepared for SPD Processing Technology

Cizek L., Rusz S., Hilser O., Śliwa R., Kuc D., Tański T., Tkocz M.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2365--2370

EN

A growing interest in wrought magnesium alloys has been noticed recently, mainly due to development of various SPD (severe plastic deformation) methods that enable significant refinement of the microstructure and – as a result – improvement of various functional properties of products. However, forming as-cast magnesium alloys with the increased aluminum content at room temperature is almost impossible. Therefore, application of heat treatment before forming or forming at elevated temperature is recommended for these alloys. The paper presents the influence of selected heat treatment conditions on the microstructure and the mechanical properties of the as-cast AZ91 alloy. Deformation behaviour of the as-cast AZ61 alloy at elevated temperatures was analysed as well. The microstructure analysis was performed by means of both light microscopy and SEM. The latter one was used also for fracture analysis. Moreover, the effect of chemical composition modification by lithium addition on the microstructure of the AZ31-based alloy is presented. The test results can be helpful in preparation of the magnesium-aluminum alloys for further processing by means of SPD methods.

13

Possibilities of biocompatible material production using conform SPD technology

Palán J., Maleček L., Hodek J., Zemko M., Dzugan J.

Archives of Materials Science and Engineering

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2017

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Vol. 88, nr 1

5--11

EN

Purpose: At present, materials research in the area of SPD (severe plastic deformation) processes is very intensive. Materials processed by these techniques show better mechanical properties and have finer grain when compared to the input feedstock. The refined microstructure may be ultrafine-grained or nanostructured, where the grain size becomes less than 100 nm. One of the materials used for such processes is CP (commercially pure) titanium of various grades, which is widely used for manufacturing dental implants. The article deals with one of the technologies available for the production of ultrafine-grained titanium: Conform technology. CP titanium processed by CONFORM technology exhibits improved mechanical properties and very favourable biocompatibility, due to its fine-grained structure. The article presents the current experience in the production of ultrafine CP titanium using this technology. The main objective of this article is describing the behaviour of CP titanium during forming in the Conform device and its subsequent use in dental implantology. Design/methodology/approach: In the present study, commercially pure Grade 2 titanium was processed using the CONFORM machine. The numerical simulation of the process was done using FEM method with DEFORMTM software. The evaluation was performed by simple tensile testing and transmission electron microscopy. The first conclusions were derived from the determined mechanical properties and based on analogies in available publications on a similar topic. Findings: This study confirmed that the SPD process improves mechanical properties and does not impair the ductility of the material. The CONFORM process enables the continuous production of ultrafine-grained or nanostructured materials. Research limitations/implications: At the present work, the results show the possible way of continuous production of ultrafine-grained or nanostructured materials. Nevertheless, the further optimization is needed in order to improve the final quality of wires and stabilize the process. As these factors will be solved, the technology will be ready for the industry. Practical implications: The article gives the practical information about the continuous production of ultrafine-grained pure titanium Grade 2 and the possibility of use this material for dental implants. Originality/value: The present paper gives information about the influence of the CONFORM technology on final mechanical and structural properties with the emphasis on technological aspects.

14

Effect of ECAP process on structure and hardness of AlMg3 aluminium alloy

Snopiński P., Tański T., Hilšer O., Lubos A.

Archives of Materials Science and Engineering

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2017

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Vol. 84, nr 2

79--85

EN

Purpose: In the present study, the effect of ECAP die and number of ECAP pressings on the structure evolution and hardness of AlMg3 aluminium alloy was investigated. Design/methodology/approach: Commercial AlMg3 aluminium alloy in the as-cast condition was processed by Equal Channel Angular Pressing method through route A using two different ECAP dies – conventional and modified with additional twist angle. Samples were processed at ambient temperature up to four passes. The investigation was carried out at ambient temperature. Two different ECAP dies were used to investigate the effect of design modification on the possibility of grain refinement to sub-micrometer size. Findings: The experimental results showed that the modification of ECAP die provides to additional grain refinement and introduces a greater amount of plastic strain into the material which results in greater increase in the properties of the investigated material. Research limitations/implications: The presented investigation results were carried out on samples, not on final products. Practical implications: Current research is moving towards to develop high strength materials with increased mechanical properties and refined microstructure that are known as ultra-fine-grained materials, compared to well-known with coarse-grained microstructure. Originality/value: The paper focuses on the investigation of microstructure evolution using mainly polarised light microscopy that reveals shear, micro-shear and slip bands that refine the microstructure of aluminium alloys. In addition, to evaluate the grain size of as ECAPed specimen, EBSD investigation was carried out.

15

Structure and properties of AlMg alloy after combination of ECAP and post-ECAP ageing

Tański T., Snopiński P., Pakieła W., Borek W., Prusik K., Rusz S.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 3

325--334

EN

Equal channel angular pressing technique (ECAP) was used before and after solution heat treatment to obtain grain refinement and strengthening of commercial Al–Mg casting alloys. The experiments were performed to investigate the strengthening effect of the alloy after various post-ECAP ageing treatments. The alloys were severely deformed at room temperature following route Bc and die channel angle of 120°. It was found that heat treatment before and after ECAP significantly affect and improves mechanical properties of aluminium alloys. It was also proven that the severe plastic deformation causes grain refinement which directly influence on properties of AlMg alloys. An increase of strength and ductility was achieved by appropriate selection of post-ECAP ageing. It is also proven that the good strengthening effect is also achieved at temperatures lower than those usually used for ageing. Based on the findings above, the tensile properties and hardness of Al–Mg alloys are discussed.

16

Aparatura wysokociśnieniowa do przeróbki plastycznej materiałów z dużymi odkształceniami na zimno

Pachla W., Skiba J., Kulczyk M., Przybysz M.

Obróbka Plastyczna Metali

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2015

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T. 26, nr 4

283--306

PL

Obróbka plastyczna z dużymi odkształceniami powoduje rozdrobnienie mikrostruktury materiałów co skutkuje wzrostem własności mechanicznych. Aby powstrzymać utratę spójności materiału podczas odkształcania należy zachować duże naprężenia ściskające w strefie odkształcenia. W pracy przedstawiono korzystny wpływ wysokiego ciśnienia na wzrost plastyczności i powstrzymanie pękania poprzez zastosowanie metody przeciskania przez równoosiowy kanał kątowy ECAP i wyciskania hydrostatycznego HE. Opisano konstrukcje pras, ich podstawowe osiągi i parametry procesów. Scharakteryzowano prasę do HE o średnicy 22mm do 2 GPa i stanowisko do procesu ECAP o przekroju 30mm i nacisku do 2.3 GPa, uwzględniając optymalizowanie konstrukcji z wykorzystaniem metod analitycznych opartych o teorię sprężystości i plastyczności Lame’a, oraz metodą elementów skończonych MES. Analizie poddano materiały komór roboczych i podstawowe parametry procesu. Zredukowane naprężenia węzłowe komory ECAP ze stali S600 i komory HE ze stali 45HNMFA wykazały, że wytrzymałości dla maksymalnych obciążeń nie są przekroczone. Dla stopu aluminium 6060 optymalny kąt naroża kwadratowego kanału ECAP wynosi 16º. Przedstawiono, określone metodą MES, niejednorodność odkształcenia plastycznego przy wyciskaniu hydrostatycznym kwadratowego profilu miedzi oraz obszary lokalizacji umocnienia podczas wyciskania złożonego profilu z tytanu. Opisano łatwość łączenia ze sobą obu technik SPD i jego wykorzystania w celu wzmacniania efektu rozdrabniania ziaren do rozmiarów nanometrycznych. Wykazano, ze rozdrabnianie mikrostruktury metodami deformacji pod wysokim ciśnieniem prowadzi do wzrostu wytrzymałości o ponad 70% (miedź i stop tytanu Ti grade 5) oraz granicy plastyczności powyżej 100% (stop niklu C65500 i aluminium 5483). Przedstawiono obszary możliwych zastosowań przetworzonych materiałów jak instrumentarium i implanty medyczne, elementy złączne, oprzyrządowanie spawalnicze czy rury i profile złożone.

EN

Severe plastic deformation working results in refinement of the microstructure of materials, improving their mechanical properties. To prevent loss of the material's cohesion during deformation, high compressive stresses must be maintained in the deformation zone. This article presents the beneficial use of high pressure to increase plasticity and prevent cracking, by applying the equal channel angular pressing(ECAP) and hydrostatic extrusion (HE) methods. Basic press designs, performances, and process parameters are described. The HE press, with a diameter of 22mm, up to 2 GPa and an ECAP station with a cross-section of 30mm and pressing force up to 2.3 GPa are characterized, with design optimization by means of analytical methods based on Lame's theory of elasticity and plasticity and the finite-element method (FEM). The materials of working chambers and basic process parameters are analyzed. Reduced node stresses of the ECAP chamber, made of S600 steel, and the HE chamber, made of 45HNMFA steel, show that the materials' strength is not overcome at their respective maximum loads. For the 6000 aluminum alloy, the optimal angle of the square corner of the ECAP channel is 16º. Non-uniformity of plastic deformation during hydrostatic extrusion of a square copper section and hardening areas during extrusion of titanium sections determined using FEM are presented. The ease of combining both of these SPD techniques and using them to amplify the grain refinement effect to nanometric dimensions are described. It is shown that refinement of the microstructure by highpressure deformation leads to improvement of strength by over 70% (copper and grade 5 Ti alloy) and yield point above 100% (C65500 nickel and 5483 aluminum alloys). Possible areas of application for worked materials are presented, such as surgical instruments and medical implants, fixing elements, welding tools, pipes and complex sections.

17

Models of damage mechanism of glidcop Cu-Al2O3 micro and nanomaterials

Besterci M., Sülleiová K., Ballóková B., Velgosová O.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 69, nr 2

79--85

EN

Purpose:of this paper was to analyze the fracture mechanism before and after ECAP in the Glidcop AL-60 grade (with 1.1 wt. % of Al2O3) system and to propose damage and/or fracture mechanisms models by means of the method “in situ tensile test in SEM”. Design/methodology/approach: The method of “in-situ tensile testing in SEM” was used for investigations of fracture mechanisms because it enables to observe and document deformation processes directly, thank to which the initiation and development of plastic deformation and fracture can be reliably described. Analyses of microstructure and fracture surfaces were carried out by means of the scanning electrone microscope JEM 100 C. Findings: The deformation and fracture mechanisms of Glidcop AL-60 grade with 1.1 wt. % of Al2O3 phase (1.62 vol. % of Al2O3) were analyzed before and after ECAP (Equal Channel Angular Pressing). Before ECAP it was shown that the deformation process causes increasing of pores and formation of cracks. Decohesion of small Al2O3 particles and clusters occurs and the final fracture path is influenced by coalescence of cracks originated in such. The principal crack propagates towards the sample exterior surface. After ECAP initial cracks were formed in the middle of the specimen first of all in the triple junctions of nanograins and together with decohesion of Al2O3 particles and clusters at small strains lead to the failure. Research limitations/implications: To develop more complex knowledge about the objective material further studies are necessary to focus also on the other factors which besides the secondary phase amount can influence the failure mechanism, e.g. strain rate, temperature and others. Complex analysis allows better understanding of material behavior at different conditions and possibilities of application of products from these materials will be thereby improved. Practical implications: This article completes knowledge about damage/fracture mechanisms and processes of the material with 1.1 wt. % of Al2O3 phase. Some materials with the different volume fraction of a secondary phase have been studied. This concrete one with 1.1% clarifies the fracture process of Glidcop AL-60 material not only after mechanical alloying process but also after ECAP treatment. An effect of the ECAP process on the final material was crucial because not only microstructure but also failure mechanism have been changed. Originality/value: Based on the experimental observations original models of damage and/or fracture mechanisms were proposed.

18

Effects of ECAP on the mechanical properties of Mg-Al2O3 nanocomposites

Ballóková B., Besterci M., Sülleiová K., Balog M., Huang S. J.

Journal of Achievements in Materials and Manufacturing Engineering

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2015

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Vol. 69, nr 1

10--17

EN

Purpose: The purpose of this paper is the study of the effect of equal channel angular pressing (ECAP) on the mechanical properties of the Mg-Al2O3 nanocomposites. Magnesium and its alloys have excellent physical and mechanical properties for a number of applications. In particular its high strength: weight ratio makes it an ideal metal for automotive and aerospace applications, where weight reduction is of significant concern. Design/methodology/approach: Severe plastic deformation is a useful methodology to refine the grain size to the submicron or even nanometer size Findings: In the present work the influence of number of passes of ECAP by grain size, evolution of microstructure, mechanical properties and fracture of magnesium composites with different volume fraction of Al2O3 particles has been investigated by means of optical microscopy, tensile tests and scanning electron microscopy. Research limitations/implications: It has been found, that the grain size decreases with increasing number of passes. The mechanical properties of magnesium alloys are significantly influenced by the testing temperature leading to a decrease in the strength, by reinforcement and/or grain reinforcement leading to an increase in the strength. Originality/value: From previous studies, it was found that the MMCs using different size particles and different ECAP passes can improved the mechanical properties. But the research of Mg MMCs reinforcement with different wt.% nanoscale Al2O3 particles is not adequate.

19

New Approach In The Properties Evaluation Of Ultrafine-Grained OFHC Copper

Kvačkaj T., Kováčová A., Bidulská J., Bidulský R., Kočičko R.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

605--614

PL

W pracy zbadano szczegółowo statyczne, dynamiczne i tribologiczne właściwości ultra drobnoziarnistej (UFG) beztlenowej miedzi o wysokiej przewodności cieplnej (OFHC). W celu oceny właściwości mechanicznych przy różnych szybkościach odkształcenia, miedź OFHC badano za pomocą dwóch urządzeń w warunkach statycznych i dynamicznych. Ponadto miedź poddano dwóm różnym sposobom przetwarzania, co umożliwiło badanie wpływu struktury. Badanie szybkości odkształcenia i mikrostruktury koncentrowało się na zmianie właściwości mechanicznych po próbie rozciągania. Stwierdzono, że szybkość odkształcania jest ważnym parametrem wpływającym na właściwości mechaniczne miedzi. Wytrzymałość na rozciąganie wzrosła ze wzrostem szybkości odkształcenia i ten efekt był bardziej widoczny przy dużej szybkości odkształcania (ε~102s−1) . Jednak zmniejszenie obrazu przebiegało inaczej w zależności od cech mikrostruktury materiałów (struktura gruboziarnista a struktura ultra drobnoziarnista) i zadanych warunków szybkości odkształcenia podczas odkształcenia plastycznego (warunki statyczne a warunki dynamiczne). Zużycie miedzi badano za pomocą testów zarysowania. Badanie ścieżek zużycia wykazało, że delaminacja i umiarkowane utlenienie to główne mechanizmy zużycia.

20

Effect Of Severe Plastic Deformation On Microstructure Evolution Of Pure Aluminium

Leszczyńska-Madej B., Richert M. W., Perek-Nowak M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2B

1437--1440

EN

Processes of severe plastic deformation (SPD) are defined as a group of metalworking techniques in which a very large plastic strain is imposed on a bulk material in order to make an ultra-fine grained metal. The present study attempts to apply Equal-Channel Angular Pressing (ECAP), Hydrostatic Extrusion (HE) and combination of ECAP and HE to 99.5% pure aluminium. ECAP process was realized at room temperature for 16 passes through route Bc using a die having an angle of 90°. Hydrostatic extrusion process was performed with cumulative strain of 2.68 to attain finally wire diameter of d = 3 mm. The microstructure of the samples was investigated by means of transmission and scanning electron microscopy. Additionally, the microhardness was measured and statistical analysis of the grains and subgrains was performed. Based on Kikuchi diffraction patterns misorientation was determined. The measured grain/subgrain size show, that regardless the mode of deformation process (ECAP, HE or combination of ECAP and HE processes), grain size is maintained at a similar level – equal to d = 0.55-0.59 μm. A combination of ECAP and HE has achieved better properties than either single process and show to be a promising procedure for manufacturing bulk UFG aluminium.