Wyniki wyszukiwania - BazTech

1

Experimental investigations of the pure copper produced by equal channel angular pressing

Greger M., Muskalski Z., Wiewiórowska S.

Hutnik, Wiadomości Hutnicze

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2015

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Vol. 82, nr 1

27--30

EN

Equal channel angular pressing (ECAP) is one of the methods of severe plastic deformation (SPD) that produces ultra-fine grained materials. Experiments were conducted in order to analyses the influence of equal-channel angular pressing on the microstructure and hardness of copper. The samples were processed by ECAP trough total of 14 passes at 20°C using the processing route BC. The ECAP processing refines the grain size. The hardness increases with the number of passes, i.e. it increases with a decrease in the grain size.

PL

Metoda przeciskania przez kanał kątowy (ECAP) jest jedną z metod przeróbki plastycznej, pozwalającą na otrzymanie materiału charakteryzującego się ultradrobnoziarnistą strukturą. Badania eksperymentalne przeprowadzono w celu oceny wpływu zastosowania procesu przeciskania przez kanał kątowy na mikrostrukturę i twardość miedzi. Proces prowadzono w 14 przepustach w temperaturze 20°C. Zastosowanie procesu ECAP wpływa na rozdrobnienie ziarna. Twardość miedzi wzrasta wraz z liczbą przepustów, tzn. wzrasta wraz ze spadkiem rozmiaru ziaren.

2

Influence of technology rotary forging and drawing on structure and properties of tungsten wires

Greger M., Muskalski Z.

Hutnik, Wiadomości Hutnicze

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2013

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Vol. 80, nr 1

31--36

EN

Thin tungsten wires are thanks to their mechanical and physical properties still in the focus from the viewpoint of production of high-temperature structural materials used for example in lighting engineering. The input semi-products for production of thin tungsten wires are obtained by powder metallurgy. Mechanical properties of thin tungsten wires depend significantly on purity of the input raw materials (powders) and their processing, as well as on thermo-mechanical conditions for forming, in this case specifically on forging and drawing. In this connection special attention must be paid to forming parameters and to their optimisation aimed at achievement of the required mechanical properties of produced wires.

PL

Cienkie druty wolframowe dzięki swoim mechanicznym i fizycznym właściwościom wciąż znajdują się w centrum zainteresowania producentów wyrobów oświetleniowych. Własności mechaniczne cienkich drutów wolframowych w dużym stopniu zależą od czystości materiału (proszków) wykorzystywanego do ich produkcji, jak i w równym stopniu od cieplno-mechanicznych warunków ich formowania, szczególnie w przypadku zastosowania procesów kucia i ciągnienia. W związku z tym szczególny nacisk winien być położony na parametry kształtowania tego rodzaju produktów, ich optymalizację w celu osiągnięcia żądanych własności mechanicznych wytwarzanych z nich cienkich drutów.

3

Mechanical properties of ultra-fine grain titanium

Greger M., Widomska M., Kander L.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 40, nr 1

33-40

EN

Purpose: The main goal of the presented paper was to describe deformation behaviour of the commercial purity titanium during the ECAP method. Attention was paid particularly on reached mechanical properties of above mentioned material. Design/methodology/approach: Design of experiments rested in extrusion at temperature in range from room temperature up to 280°C. The way of approach was planned in investigation of imposed strain accumulation ability. Among used methods for determination of intended aims were tensile tests, TEM, SEM. Findings: Depending on imposed strain (e = 2 up to 8) was found that mechanical properties (namely tensile strength) have increased up to 960 MPa. Research limitations/implications: Developed ECAP process enables controlling morphology of microstructural constituents and workability of commercially pure titanium. Practical implications: Obtained findings may be used in process of preparing materials for medical application such as dental application where is very important factor their sensitivity to strain. Originality/value: Value of paper is mainly in observed findings that can be used in determination of process conditions at submicro or ultra-fine crystalline materials.

4

Microstructural evolution of severely deformed Ti

Greger M., Kander L., Černý M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2009

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z. 95

19-20

5

Forging magnesium alloys

Greger M., Vlček M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2009

|

z. 95

21-22

6

Structure and properties of alloys of the Mg-Al-Zn system

Cizek L., Greger M., Dobrzański L. A., Juricka I., Kocich R., Pawlica L., Tański T.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 32, nr 2

179-187

EN

Purpose: In the following paper there have been the structure and complex of mechanical properties of magnesium alloys presented which requires very often knowledge of elastic-plastic properties at elevated temperatures. These properties are connected with microstructure that is influenced by metallurgical and technological factors and conditions of exploitation. The influence of used method ECAP for superplasticity will be investigated. Design/methodology/approach: The tensile test in dependence on temperature of magnesium alloys was based on investigation of mechanical properties. The following results concern light and scanning microscopy for metallographic and fracture analyses of alloys after testing were used. Findings: Objective of this work consisted in determination of changes of elastic-plastic properties of magnesium alloy AZ91 as cast state and after heat treatment in dependence on temperature, including investigation of fracture characteristics. It was confirmed that during heating used alloy as cast state at chosen temperatures there occurs partial dissolution of minority phases. Homogenisation of microstructure is, however, accompanied by simultaneous forming of inter-granular non-integrities, which is unfavourable from the viewpoint of strength and plastic properties, especially at higher temperatures. Failure occurs practically at all temperatures basically by inter-crystalline splitting along the boundaries of original dendrites. At temperature testing near melting point of alloy the interdendrite areas melting were observed. After application ECAP the effect of superplasticity (200-400%) was occurred. Practical implications: The results may be utilized for a relation between plastic and strength properties of the investigated material in process of manufacturing and design of these materials. Originality/value: Complex evaluation of properties magnesium alloys at higher temperatures namely for explanation of fracture mechanism near the melting point. The possibility of supperplasticity effect of Mg-Al alloys was not presented yet.

7

Influence of severe plastic deformation by the ECAP method on structure and properties of the P2-04BCh steel

Greger M., Vodarek V., Kander L., Cizek L.

Archives of Materials Science and Engineering

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2009

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Vol. 37, nr 1

13-20

EN

Purpose: Maim aim of this paper is to describe the plastic deformation executed by ECAE of low carbon steel. The ECAE method lead to significant improvement of strength of investigated material. Design/methodology/approach: Experiments were planned and realised an the temperature ranging from room temperature up 280oC. After application of deformation the structure was investigated in dependence on accumulation of deformation and deformation temperature as well as abovementioned final properties. Findings: Accumulated deformation varied from the value 2 to 8. Investigation of structure by electron microscopy was made with use microscope JEOL JEM 2100. Mechanical properties were investigated by tensile test. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD) in combination with scanning electron microscope FEG SEM Philips. Practical implications: The technology ECAE was applied on low carbon steel. It was verification of ECAE application possibility on steel P2-04BCH importantly for following applying on similar kinds of steel, because ECAE deformation influence. Originality/value: The results from his work shall be useful in determining conditions for fabrication of nanocrystalline or sub-microcrystalline steel by the ECAE technology.

8

The structure of austenitic steel AISI 316 after ECAP and low-cycle fatigue

Greger M., Vodárek V., Dobrzański L., Kander L., Kocich R., Kuřetová B.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 28, nr 2

151-158

EN

Purpose: The article presents results of investigation of structure and properties of austenitic steel grade AISI 316 after application of Equal Channel Angular Pressing (ECAP) at the temperature of approx. 290° C. Design/methodology/approach: The ECAP method led to significant improvement of strength of investigated material. Experiments were planned and realised at the temperature ranging from room temperature up to above mentioned temperature. Findings: It was established with use of the EBSD technique that after 8 passes through the ECAP die the sub-grains with an angle of disorientation smaller than 10° formed less than 20% of resulting structure. Average size of austenitic grains with high angle boundary after 8 passes was approx. 0.32 µm. It was proven that the ECAP method enables obtaining of ultra fine-grained austenitic structure formed by recrystallised grains with very low density of dislocations. Practical implications: The Technology ECAP was applied on austenitic steel AISI 316. It was verification of ECAP application possibility on steel AISI 316 importantly for following applying on similar kinds of steel, because ECAP technology influence on fatigue properties was confirmed. Originality/value: It can be predicted on the basis of obtained results that, contrary to low-cycle fatigue the ultra-fine grained material will manifest at fatigue load in the mode of constant amplitude of stress higher fatigue characteristics, particularly fatigue limit.

9

Mg-Al-Zn alloys processed by SPD technologies

Greger M., Kuretova E.

Hutnik, Wiadomości Hutnicze

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2008

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Vol. 75, nr 8

476-478

EN

The paper is focused on issues of processing of non-ferrous metals in practice, namely on Mg-Al-Zn based on magnesium alloys with graded Al contents. It is well known that forming of these alloys is difficult since this feature is caused by their crystallographic arrangement. Nevertheless, application of appropriate methods of forming, such as e.g. some of SPD processes, makes it possible to achieve even in these alloys comparatively very low formability with very good results with orientation on their final mechanical properties, not only strength but also proven plastic properties. Methods ARB a ECAP were used in the described experiment.

PL

W artykule zaprezentowano wyniki badań związanych z problematyką przetwarzania metali nieżelaznych, a w szczególności stopów Mg-Al-Zn bazujących na magnezie z różną zawartością Al. Przeróbka plastyczna tego rodzaju stopów jest trudna, co jest związane z ich uporządkowaniem krystalograficznym. Jednak zastosowanie odpowiednich metod kształtowania, takich jak niektóre procesy SPD, umożliwia osiągnięcie nawet dla tych stopów, o stosunkowo niskiej odkształcalności, badzo dobrych rezultatów w zakresie właściwości mechanicznych. Dotyczy to nie tylko właściwości wytrzymałościowych, ale również właściwości plastycznych materiału. W badaniach zastosowano metody ARB oraz ECAP.

10

Structure and low-cycle fatigue of steel AISI 316 after ECAP

Greger M., Kander L., Kocich R.

Archives of Materials Science and Engineering

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2008

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Vol. 31, nr 1

41-44

EN

Purpose: Main aim of this paper is to describe the plastic deformation executed by ECAP on low cycle fatigue of steel AISI 316. Among others was attention fixed on mechanical properties after this treatment. Design/methodology/approach: Experiments were planned and realised at the temperature ranging from room temperature up to 280 °C. After application of deformation the structure was investigated in dependence on accumulation of deformation and deformation temperature as well as abovementioned final properties. Findings: Accumulated real (logarithmic) deformation varied from the value 2 to 8. Investigation of structure by electron microscopy was made with use of microscope JEOL JEM 2100. Mechanical properties were investigated by conventional tensile test and penetration test. Selected samples were subjected to low-cycle fatigue. Statistic evaluation of angular disorientation and of size of grains/sub-grains was also made with use of electron diffraction (EBSD) in combination with scanning electron microscope FEG SEM Philips. Practical implications: The Technology ECAP was applied on austenitic steel AISI 316. It was verification of ECAP application possibility on steel AISI 316 importantly for following applying on similar kinds of steel, because ECap technology influence on fatigue properties was confirmed. Originality/value: It can be predicted on the basis of obtained results that, contrary to low-cycle fatigue the ultra-fine grained material will manifest at fatigue load in the mode of constant amplitude of stress higher fatigue characteristics, particularly fatigue limit.

11

Struktura a vlastnosti vybraných hořčíkových slitin s příměsi křemíku a zirkonia

Čížek L., Greger M., Pawlica L., Prażmowski M., Sozańska M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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Vol. 321, z. 89

93-94

12

Mechanical properties of magnesium alloy AZ61 prepared ecap technology

Greger M., Čížek L., Prażmowski M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

|

Vol. 321, z. 89

123-124

13

Mechanical properties and structure of magnesium alloys with graduate content of aluminium at elevated temperatures

Čížek L., Hanus A., Greger M., Juřička I., Rusz S., Prażmowski M., Tański T., Hernas A.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2007

|

Vol. 321, z. 89

91-92

EN

At the contemporary stage of the development of the engineering thought, and the product technology itself, material engineering has entered the period of new possibilities of designing and manufacturing of elements, introducing new methods of melting, casting, forming, and heat treatment of the casting materials, finding wider and wider applications in many industry branches. Therefore the development of engineering aims at designs optimizing, reducing dimensions, weight, and extending the life of devices as well as improving their reliability [1-3]. Contemporary materials should possess high mechanical properties, physical and chemical, as well as technological ones, to ensure long and reliable use. The above mentioned requirements and expectations regarding the contemporary materials are met by the non-ferrous metals alloys used nowadays, including the magnesium alloys. Magnesium alloys and their derivatives, characterize of low density (1.5-1.8 g/cm3) and high strength in relation to their weight [1,3]. Knowledge of the relaxation properties of metal materials at elevated temperatures is necessary for the verification of susceptibility of castings to the creation of defects during the production and forming processes [1,4]. Temperature limits of materials where highest tension values are generated may be detected with tensile tests under high temperatures. Experimental investigation was made on magnesium alloy AZ91 - samples A and AZ61 - samples B (after ASTM Standard) in initial state as cast. The purpose of the measurement was the study of deformation and tension changing with temperature at the tensile test and in time with simultaneous acoustic emission (AE) measurement (in the case of alloy AZ61). These dependencies were also monitored at various temperatures of sample heating from 15°C to 400°C with crosspiece shift of 6mm/min. The measurement included material sample stress at the given temperature by tension at the INOVA electro hydraulic loading machine with a loading force of 20 kN with possibility of the acoustic emission (AE) monitoring. The test bar with 0 4 mm was warmed up in a graphite furnace in inert atmosphere (argon). The AE scanner records released elastic waves (overshoots) in a frequency band between 30 kHz and 400 kHz. The output from the scanner is carried to the AE preamplifier where it is amplified and impedance-adjusted so it is possible to be transferred to more far-reaching places. The signal is further carried to the EMIS 01 system and to the PC's hard disk and they are processed in the EXCEL. Microstructure of the alloys in initial state is formed by solid solution and by minority phases Mgn(Al,Zn)i2 in massive and dispersion form and showed dendritic segregation. During heating magnesium alloy AZ91 at chosen temperatures there occurs partial dissolution of minority phases. Homogenisation of microstructure is, however, accompanied by simultaneous forming of inter-granular non-integrities, which is unfavourable from the viewpoint of strength and plastic properties, especially at higher temperatures. Failure occurs practically at all temperatures basically by inter-crystalline splitting along the boundaries of original dendrites. Trans-crystalline plastic character of fracture in small areas at 300°C was occurred. Similar temperature dependence was occurred in the case of alloy AZ61. In this case the plasticity properties were at high level. An acoustic emission method was used for a better analysis of the course of the deformation action at the tensile test. The AE method especially enables a study of dynamics of these processes at various temperatures. The opportunity to study deformation processes preceding initiation of cracks and monitoring of initiation and crack growth as up to the macroscopic scale is a big advantage of the AE. The method is therefore used in the technical diagnostics and at a check of technological operations in the production process.

14

Superplastic properties of magnesium alloys

Greger M., Kocich R., Čižek L.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 22, nr 2

83-86

EN

Purpose: The paper summarises results of experiments aimed at development of structure of modified Mg-Al-Zn alloys at hot deformation. Design/methodology/approach: methods ARB and ECAP were used in the described experiment. It was proved that hardly forming materials could achieve very high plastic properties. Findings: After making plastics deformation, the using materials of alloys AZ61 and AZ91 analysed superplastics behaviour, it was certified by obtaining results, when ductility to rupture of alloy AZ91 was 418%, it is demonstrated at conclusion of the article. Research limitations/implications: The experiment proved big influence of previous plastics deformation to ending values of mechanical properties. It was verified that better results are at rolling in more steps compared to rolling in one pass. Practical implications: The low submission temperature at last pass through die it causes obtaining higher final properties. Originality/value: It was obtained the material about grain size d dsim 0,7 micrometres during using the technology of ECAP. Abreast of it the technology ARB enabled to get material of grain size in interval d dsim 1-10 micrometres. The second technology brings higher strength properties. Only 3 cycles were sufficient to lower original grain size under limit 10 micrometres.

15

Grain refining of Cu and Ni-Ti shape memory alloys by ECAP process

Greger M., Kocich R., Cizek L.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

247-250

EN

Purpose: This paper was aimed at verification of functionality of the ECAP technology at extrusion of the copper and Ni-Ti alloys. Design/methodology/approach: Cross-section of original samples was 8 x 8 mm and their length was 32 mm. The samples of Cu were extruded at room temperature. For the samples of Ni-Ti alloys was used the two-stage pressing, when the samples were extruded at temperature of approx. T1 = 520 degrees centigrade and T2 = 420 degrees centigrade. In order to increase the concentration of deformation in volume of the sample, the samples were turned around their longitudinal axis by 90 degrees after individual passes and they were extruded again. Analysis of structure was made by using of light microscopy. Findings: deformation forces were measured during extrusion, resistance to deformation was calculated and deformation speed was approximately determined. After individual passes there is occured an accumulation of deformation strengthening (tau3 = 745 Mpa). Research limitations/implications: Microstructure depends on experimental conditions, particularly on number of passes and on rotation of the sample between individual passes. Orginality/value: SPD techniques as ECAP process can be used for non-ferrous metals like Ti, Cu. It was approved that elevated temperature provide a successfully conditions for the fine grained final materials obtaining.

16

Fracture analysis of selected magnesium alloys after different testing methods

Čižek L., Greger M., Dobrzański L. A., Kocich R., Tański T., Praźmowski M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

131-134

EN

Purpose: of this paper is to extend a complex evaluation of magnesium alloys which requires very often knowledge mechanical properties. These properties are connected with microstructure that is influenced by metallurgical and technological factors and conditions of exploitation. Very important information for design and exploitation of these alloys is knowledge of fracture characteristics. Design/methodology/approach: Testing methods used magnesium alloys were based on tensile test and torsion test. The methods of the light microscopy and SEM for metallographic and fracture analyses of alloys after testing were used. Findings: Objective of this work consisted in determination of changes of mechanical properties and fracture characteristics of magnesium alloy in dependence on testing methods. Mg-Al alloy with graduate aluminium content as cast state and after heat treatment was used. It was confirmed that during heating at chosen temperatures there occurs partial dissolution of minority phases. Research limitations/implications: According to the alloys characteristic, the applied cooling rate and alloy additions seems to be a good compromise for mechanical properties and microstructures, nevertheless further tests should be carried out in order to examine different cooling rates and parameters of solution treatment process and aging process. Practical implications: The results may be utilized for a relation between plastic and strength properties of the investigated material in process of research and manufacturing. Originality/value: These results contribute to complex evaluation of properties magnesium alloys namely for explanation of fracture mechanism in changing condition of testing and exploitation. The results of this paper are determined for research workers deal by development new exploitations of magnesium alloys.

17

Forging and rolling of magnesium alloy AZ61

Greger M., Kocich R., Čižek L.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

447-450

EN

Purpose: The paper summarises results of experiments aimed at development of structure of modified alloy AZ61 at hot deformation. Design/methodology/approach: Deformation behaviour of alloy was verified at the temperature of 420 degrees centigrade by rolling at 380 degrees centigrade by forging, respectively. Findings: Magnesium alloy AZ 61 have hexagonal structure and their forming is at room temperatures very difficult, that's why big plastic deformations are carried out in hot condition. After plastic deformations was obtained that original grain size decreased 15 times. Research limitations/implications: This paper provide data about magnitude of deformation, strain rate and temperature of forming at different techniques of plastic deformation. It was aimed to determine the conditions for non problem rolling and forging respectively. Practical implications: Initial structure was as cast and after heat treatment T4. Heat treatment appeared much better for forming as well as forging than rolling because of state of stress. Originality/value: Role of beta phase (Mg17Al12) in these alloys at plastic forming is very important, such that how it was obtained, best final properties of AZ 61 alloy supports very fine particles, distributed into Mg matrix. Next a relevant information is that multi stage forming process is much better in comparison with a big single reduction.

18

Drawing of tungsten wire at elevated temperatures

Greger M., Muskalski Z., Kocich R., Kuretova B.

Hutnik, Wiadomości Hutnicze

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2007

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Vol. 74, nr 1-2

17-20

EN

The paper describes deformation behaviour, mechanical properties and structure of cold drawn tungsten wires and heat treated by annealing at various temperatures. Introductory part describes technological process and analysis of drawing technology. Dependence of change of mechanical properties of tungsten wires with various chemical composition on structural states caused by deformation strengthening and annealing was investigated experimentally.

PL

W pracy opisano przebieg deformacji, własności mechaniczne i strukturalne ciągnionych na zimno drutów wolframowych oraz obróbkę cieplną przez wyżarzanie w różnych temperaturach. Przedstawiono części opisu procesu technologicznego i analizę technologii ciągnienia. Przeprowadzono badania doświadczalne zależności zmian własności mechanicznych drutów wolframowych o różnym składzie chemicznym, zmian strukturalnych wywołanych przez umocnienie odkształceniowe oraz wyżarzanie.

19

Possibilities of mechanical properties and microstructure improvement of magnesium alloys

Greger M., Kocich R., Čížek L., Dobrzański L. A., Juřička I.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 2

83-90

EN

Purpose: Magnesium alloys are the very progressive materials whereon is due to improve their end-use properties, which. Especially, wrought Mg alloys attract attention since they have more advantageous mechanical properties than cast Mg alloys. Design/methodology/approach: The presented article shows some specific physical-metallurgical characteristics of magnesium alloys of the AZ91 kind after hot forming. Special attention has been focused on the analysis of mutual relations existing between the deformation conditions, microstructural parameters, and the achieved mechanical properties. Findings: The discussed topic includes namely the monitoring of the structures in the initial cast state and after the heat treatment of the T4 kind and the influence of rolling in hot state at different temperatures on this structure. The results of torsion tests of AZ91, AZ61 and AZ31 were added. Research limitations/implications: The results of this paper evinces that a combination of ECAP technology with conventional rolling is very effective tool for improve a final properties of magnesium alloys in practical use. Practical implications: It would be appropriate a extrusions processes for increasing of mechanical properties on their treatment by plastic deformations in a rolling mills. Originality/value: It is explained a big consequence of the ECAP integration between classical forming techniques.

20

Influence of ECAP technology on the metal structures and properties

Greger M., Kocich R., Čížek L., Dobrzański L. A., Widomská M.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 12

709-716

EN

Purpose: The purpose of the paper is the verification of functionality of the ECAP technology at extrusion of the copper, alluminium alloys, magnesium alloys and steel. Design/methodology/approach: Deformation forces were measured during extrusion, resistance to deformation was calculated and deformation speed was determined approximately. Analysis of structure was made with use of light microscopy and TEM. Findings: The samples of Cu and Al alloys were extruded at room temperature. For the samples of steel and AZ91 alloy was used the two-stage pressing, when the samples were extruded at temperature of approx. T1=325*C and T2=220*C. In order to increase concentration of deformation in volume of the sample the samples were after individual passes turned around their longitudinal axis by 90° and extruded again. Practical implications: Experiments on poly-crystalline copper of the grade C10200, aluminium alloy AlCu2.5Mg and steel P355Q confirmed that the ECAP method is efficient tool for refining of grain. Originality/value: Cross-section of original samples of Cu and Al alloys was 8 x 8 mm and their length was 32 mm and cross-section of original samples of steel and AZ 91 alloy was 10 x 10 mm and their length was 40 mm.