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1

Analysis and prediction of the impact of technological parameters on cutting force components in rough milling of AZ31 magnesium alloy

Kulisz M., Zagórski I., Weremczuk A., Rusinek R., Korpysa J.

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no 1

art. no. e1, 2022

EN

This paper presents the results of experimental study of the AZ31 magnesium alloy milling process. Dry milling was carried out under high-speed machining conditions. First, a stability lobe diagram was determined using CutPro software. Next, experimental studies were carried out to verify the stability lobe diagram. The tests were carried out for different feed per tooth and cutting speed values using two types of tools. During the experimental investigations, cutting forces in three directions were recorded. The obtained time series were subjected to general analysis and analysis using composite multiscale entropy. Modelling and prediction were performed using Statistica Neural Network software, in which two types of neural networks were applied: multi-layered perceptron and radial basis function. It was observed that milling with high cutting speed values allows for component values of cutting force to be lowered as a result of the transition into the high-speed machining conditions range. In most cases, the highest values for the analysed parameters were recorded for the component Fx, whereas the lowest were recorded for Fy. Additionally, the paper shows that a prediction (with the use of artificial neural networks) of the components of cutting force can be made, both for the amplitudes of components of cutting force Famp and for root mean square Frms.

2

Chip Temperature Measurement in the Cutting Area During Rough Milling Magnesium Alloys with a Kordell Geometry End Mill

Kuczmaszewski Józef, Zagórski Ireneusz, Zgórniak Piotr

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

109--119

EN

The paper presents the results of measurements of chip temperature in the cutting zone during milling. The main aim of the research was to record and compare the maximum chip temperature in consecutive frames of thermal images. An additional goal may be the influence of changes in technological parameters on the temperature of the chips in the cutting zone. Two grades of magnesium alloys were used for the tests: AZ31 and AZ91HP. The research used a carbide milling cutter with an additional chip breaker, dedicated to effective roughing of light alloys. These tool geometries can assist in the high-performance machining of magnesium alloys by efficiently splitting the chip and consequently reducing friction in the machining zone. This can reduce the cutting area temperature. The results of the research work were showed as exemplary "time" charts, box-plot charts and a summary table, which additionally included an error analysis of the measurement method. On the basis of the tests and measurements performed, it can be concluded that despite the observed chip fragmentation, the obtained temperatures can be defined as the so-called safe milling areas. During the machining tests, the risk of chip ignition during machining was not observed, also the characteristic melting points, which clearly indicates the safety of the milling process of these alloys. It has been observed that with the increase of vc and fz, there was no increase in the maximum temperature of the chip in the cutting area. This situation only occurs when increasing ap.

3

2D Geometric Surface Structure ANN Modeling after Milling of the AZ91D Magnesium Alloy

Kulisz Monika, Zagórski Ireneusz, Józwik Jerzy

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 2

131--140

EN

The paper presents the results of modeling 2D surface roughness parameters in milling by means of an artificial neural network (ANN). The AZ91D magnesium alloy was used. A HSS milling cutter was employed in the research. The main aim of the study was to obtain the lowest possible surface roughness (good quality) using a commonly available HSS cutter. The results of the research work were presented in the form of bar charts, surface charts and graphs depicting the quality of artificial neural networks. The conducted research shows that it is possible to carry out the machining processes that enable obtaining an average surface quality (defined by roughness parameters Ra, Rz, RSm, Rsk). The Ra, Rz, RSm parameters increase along with the machining parameters (fz, ap), as expected. The Rsk parameter takes (in most cases) negative values, which may indicate a surface with more intense friction and indicative of flat-topped distribution. On the other hand, the results of modeling the selected parameters – Ra, Rz, RSm – with the use of artificial neural networks allow concluding that the obtained network models show satisfactory predictive ability (R = 0.99), and thus are an appropriate tool for the prediction of surface roughness parameters.

4

Obróbka cieplno-mechaniczna stopów Mg

Sułkowski Bartosz

Stal, Metale & Nowe Technologie

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2021

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nr 9-10

44--48

PL

Stopy magnezu ze względu na mały ciężar właściwy są stosowane w tych gałęziach przemysłu, w których redukcja masy jest kluczowa. Mowa tutaj o przemyśle samochodowym, lotniczym i kosmicznym. Wadami stopów magnezu są podatność na korozję oraz słabe własności mechaniczne. Wytrzymałość na rozciąganie w stopach magnezu rzadko przekracza 300 MPa i bardzo szybko maleje wraz ze wzrostem temperatury.

EN

Due to their low specific weight, magnesium alloys are used in industries where weight reduction is crucial. We are talking about the automotive, aerospace and aerospace industries. The disadvantages of magnesium alloys are susceptibility to corrosion and poor mechanical properties. The tensile strength in magnesium alloys rarely exceeds 300 MPa and decreases very quickly as the temperature increases.

5

Microstructure of cast MgBi6X0.5 (X = Ca, Mn, Zn) alloys in peak-aged condition

Gryc Adam, Dybowski Bartłomiej, Jarosz Robert, Kiełbus Andrzej

Journal of Metallic Materials

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2021

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Vol. 73, no. 3

23--28

EN

Cast magnesium alloys are characterised by the lowest density among commercially used structural metals. They are applied mainly in the transportation industry and small, lightweight electronic devices. Due to the low operating temperature of the most widely used alloys from the Mg-Al system, alloys containing rare earth elements with the maximum working temperature reaching 300°C have been developed. However, these alloys are extremely expensive due to the low availability of RE elements. The Mg-Bi system is a promising candidate for the new magnesium-based alloys, as it reveals limited solubility of Bi in Mg enabling precipitation hardening and a high melting point of the Mg3Bi2 phase. The paper presents the results of the analysis of MgBi6 and MgBi6X0.5 (X = Ca, Mn, Zn) alloys’ microstructure in the peak-aged condition. The microstructure of the analysed alloys in the as-cast condition consists of α-Mg solid solution dendrites and Mg3Bi2+α-Mg eutectic compound. Solutionising conducted at 525°C for 8 h, followed by water quenching leads to the dissolution of the intermetallic phases in all of the investigated alloys apart of the MgBi6Ca0.5 alloy. In this case, fine intermetallic phases containing Mg, Bi, and Ca have been found after solutionising. The ageing of the alloys at 200°C results in peak hardness after 120-44 h. The heat treatment leads to the formation of fine strengthening phases within the α-Mg solid solution, characterised by a variety of morphologies -needle, platelet- or lathlike and cuboid. The needle- and platelet- or lathlike phases are found in two sizes -large, with length reaching hundreds of nanometres, and smaller, not exceeding 100 nm. Cuboid particles are found with sizes not higher than 100 nm. The addition of Mn and Zn increases precipitate volume fraction after the heat treatment. Additionally, in the case of the MgBi6Zn0.5 alloy, particles forming an angle of 120° were found, which indicates their presence at the prismatic planes of α-Mg HCP crystal lattice.

PL

Odlewnicze stopy magnezu charakteryzują się najniższą gęstością wśród wszystkich komercyjnie stosowanych stopów konstrukcyjnych. Znajdują zastosowanie głównie w przemyśle transportowym oraz małych, lekkich urządzeniach elektronicznych. Z uwagi na niską temperaturę eksploatacji najpowszechniej stosowanych stopów z układu Mg-Al, opracowano stopy, zawierające pierwiastki ziem rzadkich, znajdujące zastosowanie w temperaturach do 300°C. Jednak stopy z tej grupy są niezwykle drogie, z uwagi na ograniczoną dostępność pierwiastków ziem rzadkich. Obiecującą alternatywę stanowią stopy z układu Mg-Bi, który z uwagi na ograniczoną rozpuszczalność bizmutu w magnezie oraz wysoką temperaturę topnienia fazy Mg3Bi2 umożliwia ich umocnienie na drodze utwardzania wydzieleniowego. W artykule przedstawiono wyniki badań mikrostruktury stopów MgBi6 oraz MgBi6X (X = Ca, Mn, Zn) po starzeniu. Mikrostruktura badanych stopów w stanie lanym składa się z dendrytów roztworu stałego α-Mg oraz mieszaniny eutektycznej Mg3Bi2+α-Mg. Przesycanie, przeprowadzone w temperaturze 525°C przez 8 h z chłodzeniem w wodzie doprowadziło do rozpuszczenia faz międzymetalicznych we wszystkich badanych stopach, z wyjątkiem stopu MgBi6Ca0,5. W jego przypadku po przesycaniu zidentyfikowano w strukturze drobne fazy międzymetaliczne, zawierające Mg, Bi i Ca. Maksymalną twardość stopów po starzeniu w temperaturze 200°C osiągnięto po 120÷144 h. Zastosowana obróbka cieplna doprowadziła do utworzenia się wewnątrz ziaren roztworu stałego α-Mg drobnych faz umacniających o zróżnicowanej morfologii -od iglastej, przez płytkową, po prostopadłościenną. Zaobserwowano dwa typy wydzieleń iglastych i płytkowych -większe, o długości rzędu kilkuset nanometrów oraz mniejsze, nieprzekraczające 100 nm długości. Wydzielenia prostopadłościenne charakteryzowały się rozmiarami, nieprzekraczającymi 100 nm. Dodatek Mn oraz Zn spowodował wzrost udziału objętościowego wydzieleń po obróbce cieplnej. Dodatkowo, w przypadku stopu MgBi6Zn1,5, wydzielenia tworzyły kąt 120°C, co wskazuje na ich obecność na płaszczyznach pryzmatycznych komórki elementarnej α-Mg.

6

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.

7

Protection properties of conversion coatings based on nitrates for resorbable Mg alloy

Cesarz-Andraczke Katarzyna

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 1

art. no. e136045

EN

In this work, conversion coatings based on nitrates Ca(NO 3) 2 and Zn(NO 3) 2 were produced on the surface of MgZn49Ca4 to protect against corrosion. The main aim of this study was to prepare dense and uniform coatings using a conversion method (based on nitrates Ca(NO 3) 2 and Zn(NO 3) 2) for resorbable Mg alloys. The scientific goal of the work was to determine the pathway and main degradation mechanisms of samples with nitrate-based coatings as compared with an uncoated substrate. Determining the effect of the coatings produced on the Mg alloy was required to assess the protective properties of Mg alloy-coating systems. For this purpose, the morphology and chemical composition of coated samples, post corrosion tests and structural tests of the substrate were performed (optical microscopy, SEM/EDS). Immersion and electrochemical tests of samples were also carried out in Ringer’s solution at 37°C. The results of immersion and electrochemical tests indicated lower corrosion resistance of the substrate as compared with coated samples. The hydrogen evolution rate of the substrate increased with the immersion time. For coated samples, the hydrogen evolution rate was more stable. The ZnN coating (based on Zn(NO 3) 2) provides better corrosion protection because the corrosion product layer was uniform, while the sample with a CaN coating (based on Ca(NO 3) 2) displayed clusters of corrosion products. It was found that pitting corrosion on the substrate led to the complete disintegration and non-uniform corrosion of the coated samples, especially the CaN sample, due to the unevenly-distributed products on its surface.

8

Investigations of TiO₂, Ti/TiO₂, and Ti/TiO₂/Ti/TiO₂ coatings produced by ALD and PVD methods on Mg-(Li)-Al-RE alloys substrates

Staszuk Marcin, Reimann Łukasz, Ściślak Aleksandra, Jaworska Justyna, Pawlyta Mirosława, Mikuszewski Tomasz, Kuc Dariusz, Tański Tomasz, Kříž Antonín

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2021

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Vol. 69, nr 5

art. no. e137549

EN

Magnesium alloys have recently become increasingly popular in many sectors of the industry due to their unique properties, such as low density, high specific strength, vibration damping ability along with their recyclability and excellent machinability. Nowadays, thin films have been attracting more attention in applications that improve mechanical and corrosion properties. The following alloys were used for the coated Mg-Al-RE and the ultra-light magnesium-lithium alloy of the Mg-Li-Al-RE type. A single layer of TiO2 was deposited using the atomic layer deposition ALD method. Multiple layers of the Ti/TiO₂ and Ti/TiO₂/Ti/TiO₂ type were obtained by the MS-PVD magnetron sputtering technique. Samples were investigated by scanning and a transmission electron microscope (SEM, TEM) and their morphology was studied by an atomic forces microscope (AFM). Further examinations, including electrochemical corrosion, roughness and tribology, were also carried out. As a result of the research, it was found that the best electrochemical properties are exhibited by single TiO2 layers obtained by the ALD method. Moreover, it was found that the Ti/TiO₂/Ti/TiO₂ double film has better properties than the Ti/TiO₂ film.

9

Electrodynamic treatment of structural elements made of aluminium and magnesium alloys

Lobanov Leonid M., Pashchin Nikolaj A., Kondratenko Igor P., Sidorenko Yuriy M., Ustimenko Pawel R.

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2021

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Vol. 65, No. 2

17--30

EN

The article discusses the electrodynamic treatment (EDT) of thinwalled welded structures and EDT equipment, presents results of mathematical modelling concerning the effect of EDT on stresses in welded sheets made of aluminium alloy AMg6 as well as discusses the effect of EDT on the plastic strain mechanism. In addition, the article presents tests results concerning the effect of EDT during the welding of ship structures made of AMg6 plates and discusses the role of EDT in bulge formation. In addition, the article discusses the application of EDT during the repair welding of aero-engine nacelles made of magnesium alloy ML10 and the effect of EDT on openings in an airplane wing stinger in relation to its service life.

PL

Omówiono zasadę obróbki elektrodynamicznej (EDT) cienkościennych konstrukcji spawanych i opracowaną aparaturę do EDT. Przedstawiono wyniki modelowania matematycznego wpływu EDT na stan naprężenia spawanej płyty ze stopu AMg6 oraz badań wpływu elektrodynamicznych oddziaływań na mechanizm odkształcenia plastycznego. Podano wyniki wpływu EDT na odkształcenia typu wybrzuszenie powstające podczas spawania konstrukcji okrętowych z blach AMg6. Omówiono przykład zastosowania EDT podczas spawania naprawczego gondoli silnika lotniczego z stopu magnezu ML10 oraz wpływ EDT otworów podłużnicy skrzydła samolotu na trwałość zmęczeniową.

10

Ultrasonic Assisted Active-Passive Filling Friction Stir Repairing to Eliminate Volume Defects

Wang Tao, Gong Xue, Ji Shude, Xue Gang, Lv Zan

Archives of Metallurgy and Materials

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2021

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Vol. 66, iss. 1

217--222

EN

Ultrasonic assisted active-passive filling friction stir repairing (A-PFFSR) was proposed to repair volume defects in the metallic parts. Sound joints without interfacial defects could be achieved. Firstly, the ultrasonic was beneficial to improving material flow and atom diffusion, and then eliminated kissing bond defects compared to conventional A-PFFSR joints. Secondly, the equiaxed grains were refined by ultrasonic vibration. Lastly, the repairing passes were reduced due to the ultrasonic, which decreased softening degree of the repaired joints. The maximum tensile strength of 150 MPa was achieved. Therefore, this strategy to repair the volume defects is feasibility and potential in the remanufacturing fields of aerospace and transportation.

11

Effect of Gadolinium on the Microstructure of Magnesium Alloy AZ91

Rapiejko Cezary, Mikusek D., Just P., Pacyniak T.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 1

31--36

EN

The paper presents the results of research related to the possibility of inoculation of the AZ91 magnesium alloy casted into ceramic moulds by gadolinium. Effects of gadolinium content (0.1–0.6 wt%) on microstructure of the AZ91 alloy under as-cast state were investigated. The influence of the inoculator on the formation of the microstructure investigated by means of the thermal and derivative analysis by analysing the thermal effects arising during the alloy crystallization resulting from the phases formed. The degree of fragmentation of the microstructure of the tested alloys was assessed by means of the light microscopy studies and an image analysis with statistical analysis was performed. Conducted analyses have aimed at examining on the effect of inoculation of the gadolinium on the differences between the grain diameters and average size of each type of grain by way of measuring their perimeters of all phases, preliminary αMg and eutectics αMg+γ(Mg17Al12) in the prepared examined material.

12

Synergistic effects of alloying, homogenization, and hot extrusion on the mechanical properties of as-cast Mg–Al–Ca magnesium alloys

Nasiri Zahra, Mirzadeh Hamed, Khorrami Mahmoud Sarkari, Emamy Massoud

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

691--698

EN

Synergistic effects of partial replacement of Al with Ca, homogenization heat treatment, and hot extrusion on the microstructure and mechanical properties of Mg–(7-x)Al–xCa magnesium alloys were studied. The Mg17Al12 compound in Mg–7Al alloy, Mg17Al12 and Al2Ca compounds in AX52 alloy, Al2Ca and Mg–Al–Ca compounds in AX43 alloy, and Mg–Al–Ca compound in AX25 were characterized. The as-cast alloys were quite brittle with low strength values due to the deleterious effects of the continuous intergranular brittle constituents that completely masked the alloying effect. Homogenization resulted in the spheroidization of the eutectic constituents and gave the alloys some tensile ductility, which was remarkable for the AX43 alloy due to its fine grain size. Hot extrusion resulted in the fragmentation and dispersion of particles as well as formation of equiaxed, fine microstructures by the recrystallization processes, which led to the profound enhancements of the tensile properties in terms of both strength and elongation to failure. The product of strength and ductility of ~ 5500 MPa.% for the extruded AX43 alloy was far better than the value of ~ 314 MPa.% for the as-cast counterpart.

13

Galwaniczne powłoki niklowe na stopach magnezu

Boczkal Sonia, Gawlik Maciej, Karaś Michał, Kozik Anna, Mitka Monika, Nowak Marek, Żelechowski Janusz

Stal, Metale & Nowe Technologie

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2020

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nr 3-4

72--76

PL

W pracy przedstawiono wyniki badań wytwarzania kompozytowych powłok niklowych zbrojonych cząstkami węglika krzemu o wielkości nanometrycznej. Powłoki osadzano elektrolitycznie na podwarstwie Ni-P z kąpieli typu Wattsa z dodatkami substancji organicznych. Przedstawiono mikrostruktury uzyskanych powłok, wyniki badań korozyjnych oraz badań przyczepności powłok metodą udaru cieplnego.

EN

The paper presents the results of the studies of electrodeposited composite nickel coatings reinforced with nanometer-size silicon carbide particles. The coatings have been deposited on the Ni-P sublayer in Watts-type solution with organic additives. The microstructure of the coatings, as well as the results of corrosion tests and coating adhesion tested with the method of the heat shock have been also presented.

14

The Effect of Extrusion in the Complex Strain State on the Microstructure and Mechanical Properties of MgAlZn Magnesium Alloys

Bednarczyk I., Kuc D., Tomaszewska A., Tkocz M.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1121--1128

EN

The paper presents the results of tests concerning the effect of the extrusion process in the complex strain state on the microstructure and properties of one of magnesium alloy with aluminium, zinc and manganese, designated AZ61. Due to its specific gravity, it is increasingly being used in the automotive and aerospace industries to reduce the weight of structural elements. As a result of plastic deformation processes, rods with a diameter of 8, 6 and 4 mm were obtained from AZ61 magnesium alloy. The microstructure analysis was performed using light and electron microscopy (STEM) techniques in the initial state and afterplastic deformation. Microstructure studies were supplemented with a quantitative analysis using the Metilo program. A number of stereological parameters were determined: average diameter of grain, shape factor. A static tensile test was carried out at 250ºC and 300ºC, at deformation rates of 0.01, 0.001 and 0.0001 m·s-1. Better plastic properties after deformation using KoBo methodwere obtained than with conventional extrusion.

15

Analysis of the Effect of Rolling Speed on the Capability to Produce Bimodal-Structure AZ31 Alloy Bars in the Three-High Skew Rolling Mill

Stefanik A., Szota P., Mróz S.

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 1

329--335

EN

A numerical analysis of the process of single-pass rolling of AZ31 magnesium alloy bars in the three-high skew rolling mill has been carried out in the study. Based on the obtained investigation results, the effect of rolling speed on the band twist and the state of stress and strain occurring in the rolled band has been determined. From the obtained results of the numerical studies it has been found that with the increase in rolling speed the unit band twist angle θ, increase, which translates into an increase in the value of tangential stress in the axial zone of the rolled bar. This contributes directly to an increase in redundant strain in the rolled bar axial zone, which brings about a structure refinement. To verify the effect of rolling speed on the flow pattern and the stress and strain state, experimental tests were carried out. It has been found from the tests that the band twist (flow pattern) contributes to obtaining a bimodal structure in the bar cross-section.

16

The potential of SLM technology for processing magnesium alloys in aerospace industry

Kurzynowski T., Pawlak A., Smolina I.

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

327--339

EN

Selective Laser Melting (SLM) of magnesium alloys is the technology undergoing dynamic development in many research centres. The results are promising and make it possible to manufacture defect-free material with better properties than those offered by the manufacturing technologies used to date. This review aims to evaluate present state as well as main challenges of using Laser Powder Bed Fusion (L-PBF) for processing magnesium alloys as an alternative way to conventional technolo-gies to manufacture parts in the aerospace industry. This literature review is the first one to outline information concerning the potential to use magnesium alloys in the aerospace industry as well as to summarise the results of magnesium alloy pro-cessing using AM technologies, in particular L-PBF. The available literature was reviewed to gather information about: the use of magnesium alloys in the aerospace industry-the benefits and limitations of using magnesium and its alloys, examples of applications using new processing methods to manufacture aerospace parts, the benefits and potential of using L-PBF to process metallic materials, examples of the use of L-PBF to manufacture aerospace parts, and state-of-the-art research into L-PBF processing of magnesium and magnesium alloys.

17

The microstructure and creep properties of as-cast Mg-Sn-Si-(Al) magnesium alloys

Rzychoń Tomasz

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

481--493

EN

Magnesium alloys containing rare earth metals exhibit good creep resistance up to 300 °C and good tensile properties at ambient temperature. The high cost of rare earth has led to studies regarding the creep resistance of Mg alloys with cheap alloying elements (Sn, Ca, Si) that could be substituted for Mg-RE alloys. In this paper, the influence of Si and Al on microstructure and mechanical properties of Mg-7Sn alloy was investigated using optical (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction analysis (XRD), tensile tests and creep tests at 200–250 °C. Microstructure of as-cast alloys consists of α-Mg matrix and intermetallic compounds at the interdendritic regions. Heat treatment consisting of solid solution treatment and ageing increases the tensile properties at ambient temperature due to the precipitation of the fine Mg2Sn phase. The creep resistance of aged Mg-7Sn alloy is poor. The addition of Si and Al to Mg-7Sn alloy has resulted in improving the creep resistance due to the refinement of Mg2Sn phase and the appearance of Mg2Si phase at the grain boundaries. The Mg-7Sn-1Si alloy exhibits better creep resistance at 200 °C than Mg-7Sn-5Si and Mg-7Sn-5Si-2Al alloys. The Mg-7Sn alloys with 5% Si have better creep properties at 250 °C in comparison to Mg-7Sn-1Si alloy.

18

Superplastic deformation of Mg–9Li–2Al–0.5Sc alloy after grain refinement by KoBo extrusion and cyclic forging

Dutkiewicz Jan, Kalita Damian, Maziarz Wojciech, Faryna Marek

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

343--353

EN

The quaternary Mg–9Li–2Al–0.5Sc alloy (in wt%) was prepared from pure components. After homogenization, the alloy was subjected to severe plastic deformation by KoBo extrusion and cyclic forging leading to grain refinement in the range of 0.5–2 µm of hexagonal close-packed (HCP) α phase. Deformed alloys showed high ultimate tensile strength near 200 MPa and good elongation in the range 30–40% at room temperature (RT). Large elongations close to 200% were obtained during the tensile test at a temperature of 200 °C. Deformed samples showed the presence of multiple voids confirming grain boundary sliding mechanism of deformation. Twins on {101-2} planes were identified using electron backscatter diffraction analysis, being in a good agreement with the earlier observation of Mg–Li and Mg–Sc alloys. Intermetallic phases such as cubic MgSc were identified in deformed alloys mostly within HCP α phase, whereas HCP MgSc2 particles were observed within body-centered cubic (BCC) β phase. Intermetallic phases were responsible for RT strengthening of alloys and slightly lower tensile elongation during superplastic deformation. Formation of the HCP α phase was observed within the BCC β phase in tensile deformed alloys. Atomic-level nucleation of HCP phase within the β phase was identified by the use of high-resolution transmission electron microscopy technique.

19

Improving the workability of materials during the dieless drawing processes by multi-pass incremental deformation

Milenin Andrij, Furushima Tsuyosh, Du Peihua, Pidvysots’kyy Valeriy

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

323--336

EN

The paper explores the new method of improving the workability of materials in the dieless drawing processes. The proposed method is based on the implementation of a multi-pass incremental deformation. Moreover, in each pass, strain and strain rate sensitivity of flow stress should be positive and significant. An approach based on the finite element calculation of instability coefficient of plastic deformation and simultaneous modeling of material ductility were applied for prediction of the workability. Two dieless drawing processes have been investigated. The difference was related to the heating system-induction heating and laser heating. FE simulations and experimental tests for three materials, two magnesium alloys (MgCa0.8 and MgNi19) and pure copper were performed. It was shown that the most effective increase in workability by multi-pass deformation can be achieved using laser dieless drawing. This is possible due to the shorter heating area and, as a consequence, the larger strain rate, which leads to better stability of the deformation process.

20

Comparison of temperature dependence of internal damping of selected magnesium alloys

Oršulová Tatiana, Palček Peter, Uhríčik Milan

Production Engineering Archives

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2019

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Vol. 22

7--10

EN

The research is focused on the study of the temperature dependence of the internal damping of selected magnesium alloys with different contents of aluminium - AZ31 and AZ61. These alloys are currently widely used in various types of industry, mainly in the automotive industry. It belongs to a group of materials called HIDAMETS because they have excellent damping properties. The internal damping of the samples was measured on a unique ultrasonic device constructed at Žilina University in Žilina. Specimens were measured at baseline in the temperature range from 25 °C to 400 °C. Changes in internal damping caused by varying aluminium contents in investigated alloys were noted. As the aluminium content increases, maximum internal damping is achieved due to the formation, growth and subsequent dissolution of the continuous precipitate in the microstructure.