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1

The Use of Cluster Analysis to Assess the Wear Resistance of Cermet Coatings Sprayed by High Velocity Oxy-Fuel on Magnesium Alloy Substrate

Jonda Ewa, Fydrych Dariusz, Łatka Leszek, Myalska-Głowacka Hanna

Advances in Science and Technology. Research Journal

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2024

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Vol. 18, no 4

216--227

EN

Cermet coatings are one of the best surface protection of machine elements against wear. On the other hand, the most universal and economically justified method of applying such coatings is high velocity oxy-fuel (HVOF) spraying. This method makes it possible to produce coatings characterized by compact structure, low porosity and very good adhesion to the substrate. All these fundamental properties contribute to the high wear resistance of these coatings. However, carrying out full wear tests (e.g. ball-on-disc) is time-consuming, especially when it is necessary to select the proper feedstock material and carefully selected process parameters. The aim of the following researches was to statistically investigate the possibility of replacing long-term wear resistance tests with estimation of this performance on the basis of determining the fundamental mechanical properties of the coatings. Three types of coating materials were selected: WC-12Co, WC-10Co-4Cr and WC-20Cr3C2-7Ni, which were deposited on AZ31 magnesium alloy substrates from three different spray distances: 320, 360 and 400 mm. On the basis of the tests carried out and using cluster analysis techniques (the Ward and k-means methods), the relative similarity between the obtained coatings was determined. The applied methodology allowed to select from the analyzed cermet coatings such samples that were characterized by improved resistance to abrasive wear. The obtained results of the analyzes were also referred to the results of tests of resistance to abrasive wear.

2

Effect of spray distance on the microstructure and corrosion resistance of WC - based coatings sprayed by HVOF

Jonda Ewa, Łatka Leszek, Maciej Artur, Godzierz Marcin, Gołombek Klaudiusz, Radziszewski Andrzej

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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Vol. 71, nr 2

art. no. e144610

EN

Cermet coatings provide protection against aggressive operating environment of machine and device elements, such as corrosion, wear or high-temperature conditions. Currently WC-based cermet coatings are frequently used in the different industry branches. In this work, conventional WC-based powders (WC-Co and WC-Co-Cr) were sprayed with High Velocity Oxy Fuel (HVOF) onto AZ31 magnesium alloy with different spray distances (320 and 400 mm). The aim of the research was to investigate the effect of the spray distance on the microstructure of the coatings, phase composition and electrochemical corrosion resistance. Results revealed that higher spray distance results in greater porosity, 1.9% and 2.3% for 320 mm and 2.8% and 3.1% for 400 mm in case of WC-Co and WC-Co-Cr coatings, respectively. Also the influence has been observed for coatings microhardness, c.a. 1300 HV0.3 for shorter spray distance, whereas for longer one it was less than 1100 HV0.3. The corrosion resistance estimated in potentiodynamic polarization measurements was the best for WC-Co-Cr coating deposited from the shorter spray distance, corrosion current density was equal to 2.9 µA·cm-2 and polarization resistance was equal to 8424 Ω∙cm2.

3

Qualitative Research of AZ31 Magnesium Alloy Aircraft Brackets Produced by a New Forging Method

Dziubińska A., Gontarz A., Dziedzic K.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2B

1003--1008

EN

The paper reports a selection of numerical and experimental results of a new closed-die forging method for producing AZ31 magnesium alloy aircraft brackets with one rib. The numerical modelling of the new forming process was performed by the finite element method.The distributions of stresses, strains, temperature and forces were examined. The numerical results confirmed that the forgings produced by the new forming method are correct. For this reason, the new forming process was verified experimentally. The experimental results showed good agreement with the numerical results. The produced forgings of AZ31 magnesium alloy aircraft brackets with one rib were then subjected to qualitative tests.

4

Fatigue Characteristics of Selected Light Metal Alloys

Cieśla M., Junak G., Marek A.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 1

271--274

EN

The paper addresses results of fatigue testing of light metal alloys used in the automotive as well as aerospace and aviation industries, among others. The material subject to testing comprised hot-worked rods made of the AZ31 alloy, the Ti-6Al-4V two-phase titanium alloy and the 2017A (T451) aluminium alloy. Both low- and high-cycle fatigue tests were conducted at room temperature on the cycle asymmetry ratio of R=-1. The low-cycle fatigue tests were performed using the MTS-810 machine on two levels of total strain, i.e.Δεc= 1.0% and 1.2%. The high-cycle fatigue tests, on the other hand, were performed using a machine from VEB Werkstoffprufmaschinen-Leipzig under conditions of rotary bending. Based on the results thus obtained, one could develop fatigue life characteristics of the materials examined (expressed as the number of cycles until failure of sample Nf) as well as characteristics of cyclic material strain σa=f(N) under the conditions of low-cycle fatigue testing. The Ti-6Al-4V titanium alloy was found to be characterised by the highest value of fatigue life Nf, both in lowand high-cycle tests. The lowest fatigue life, on the other hand, was established for the aluminium alloys examined. Under the high-cycle fatigue tests, the life of the 2017A aluminium and the AZ31 magnesium alloy studied was determined by the value of stress amplitude σa. With the stress exceeding 150 MPa, it was the aluminium alloy which displayed higher fatigue life, whereas the magnesium alloy proved better on lower stress.

5

Fabrication and properties of ZrO2/AZ31 nanocomposite fillers of gas tungsten arc welding by accumulative roll bonding

Sabetghadam-Isfahani A., Zalaghi H., Hashempour S., Fattahi M., Amirkhanlou S., Fattahi Y.

Archives of Civil and Mechanical Engineering

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2016

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Vol. 16, no. 3

397--402

EN

In the present study, a new method for fabricating ZrO2/AZ31 nanocomposite fillers of gas tungsten arc (GTA) welding was developed by applying accumulative roll bonding (ARB) to the magnesium sheets coated with ZrO2 nanoparticles. The purpose of ARB was to create a uniform dispersion of ZrO2 nanoparticles in the fillers and to form a good interfacial bonding between the magnesium matrix and ZrO2 nanoparticles. After welding, the effect of ZrO2 nanoparticles on the microstructure and mechanical properties of weld was evaluated. The test results showed that the yield strength of weld was greatly increased when using the nanocomposite fillers. The improvement in the yield strength was attributed to the grain refinement, coefficient of thermal expansion mismatch and Orowan strengthening mechanisms.

6

Badania warunków tarcia stopu magnezu AZ31 w zakresie temperatury kształtowania plastycznego na gorąco

Dziubińska A., Gontarz A., Wójcik Ł.

Hutnik, Wiadomości Hutnicze

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2015

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Vol. 82, nr 8

527--532

PL

W opracowaniu przedstawiono wyniki badań warunków tarcia w zakresie parametrów kształtowania plastycznego na gorąco stopu magnezu AZ31. Celem badań było wyznaczenie wartości czynników i współczynników tarcia charakteryzujących odpowiednio model tarcia stałego oraz model Coulomba przy różnych warunkach smarowania. W badaniach zastosowano metodę spęczania pierścieni. Próbki ze stopu AZ31 nagrzewano do temperatur: 250°C, 350°C oraz 450°C. Testy wykonano w warunkach tarcia suchego oraz z zastosowaniem smarów: łoju z grafitem oraz na bazie dwusiarczku molibdenu. Wartości czynników i współczynników tarcia wyznaczono na podstawie porównania wyników doświadczalnych z rezultatami symulacji przeprowadzonych testów. Za optymalną przyjmowano taką wartość współczynnika lub czynnika tarcia, która zapewniła najlepszą zbieżność pomiędzy teoretycznymi i doświadczalnymi wymiarami spęczonych próbek. Na podstawie uzyskanych rezultatów określono wpływ temperatury na warunki tarcia oraz skuteczność użytych smarów w odniesieniu do badanego stopu.

EN

The paper reports the results of investigations of friction in metal forming of AZ31 magnesium alloy. The aim of the investigation was to determine both friction factors and coefficients of friction for the constant friction model and the Coulomb model of friction with respect to temperature in hot metal forming processes for this alloy using different lubricants. The tests were performed by the upsetting method for rings. Ring-shaped specimens made of AZ31 magnesium alloy were heated to 250°C, 350°C and 450°C. The tests were performed under dry friction conditions using two types of lubricants: tallow with graphite and molybdenum disulfide. Friction factors and coefficients of friction were determined based on the experimental and numerical results. The values of friction factors and coefficients of friction showing the best agreement between the numerical and experimental results of specimen dimensions were considered optimum. In addition, the results were used to determine the effect of temperature on friction ands well as the effectiveness of the applied lubricants with respect to the tested alloy.

7

Model zmian mikrostruktury i plastyczności odkształcanego na gorąco stopu magnezu Mg-Al-Zn

Kuc D.

Rudy i Metale Nieżelazne

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2012

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R. 57, nr 4

257-262

PL

W artykule zaprezentowano model zmian mikrostruktury i plastyczności opracowany dla stopu magnezu AZ31. We wcześniejszych pracach bazując na próbach jednoosiowego ściskania na gorąco opracowano funkcję naprężenia uplastyczniającego. Na podstawie wyznaczonych krzywych relaksacji i badań ilościowych struktury wyznaczono wskaźniki mięknięcia i opracowano równania opisujące zmiany rozmiaru ziarna. Wyznaczone współczynniki równań wprowadzono do kodu programu symulacyjnego. Obliczenia wykonano dla zadanych wartości temperatury 450-250 [stopni]C i prędkości 0,01-10 s-1, co odpowiada zakresowi temperatury walcowania tego stopu. Opracowane zależności poprawnie odwzorowują płynięcie plastyczne i zmiany średniego rozmiaru ziarna stopu magnezu. Model umożliwia dobór parametrów procesu walcowania na gorąco tego stopu dla uzyskania założonej mikrostruktury.

EN

Since the beginning of the 21st century, one can observe significant increase of the interest in magnesium alloys as applied in automotive, aerospace industry, as well as in space technology. The development of deformable magnesium alloys and plastic forming methods has been strongly limited so far. Plastically worked magnesium alloys are very rarely used due to technological difficulties in plastic working and to high production costs. Alloys for plastic working are more and more promising, however, due to the elaboration of new ones and development of the technologies of processing them. A major drawback of magnesium and its alloys is their low deformability at ambient temperature, which is due to the type of crystallographic lattice. The favorable properties of magnesium account for the fact that it is applied not only in cast structural components but also in those subjected to plastic working. This paper describe reological model of flow curves provide for dynamic recrystallization process. Flow curves was developed by "inverse" method during axial-symmetric compression test. Formulas, which describe kinetics of dynamic recrystallization and changes of dynamic recrystallized grain size of tested steel were developed. Good compatibility between flow curves of a rheological model with data known of research was obtain. Relaxation curve was developed by in using simulator for magnesium AZ31 alloy grade. Structural examination was carried out using light microscopy. Deformation mode such as slip and twinning, which take place during hot-deformation, have been detected. Selected method in connecting with structure researches is enable to determination of static and metadynamic equations for developing of hot deformed structural model. To validate the development model, it was applied to the simulation of the four stages axial-symmetrical strain compression test. This model can be easily implemented in any finite element software.

8

Thickness evaluation of the carbon coatings manufactured on magnesium alloys using optical profiler

Gołąbczak M., Jacquet P.

Journal of Machine Engineering

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2012

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Vol. 12, No. 2

29--36

EN

One of the problems in identification of carbon nanocoatings is measurement of their thickness. There are a lot of methods which allow for determination of thickness i.e. SEM analysis of cross section of sample with manufactured coating, nanoindentation analysis with using DSP (Digital Signal Processing) method, roughness analysis with using different kind of profilers. In this paper the technology of manufacturing of carbon coatings on AZ31 magnesium light alloy has been depicted and optical profiler has been used for thickness evaluation of these coating. Obtained results allowed for precise estimation of manufactured carbon coatings thickness. In this way it was also possible to compare obtained thickness results with thickness evaluated by other methods.

9

The temperature dependence of internal damping and elastic modulus of Mg alloy

Kasencak M., Palcek P., Blazek D.

International Journal of Applied Mechanics and Engineering

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2010

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Vol. 15, no 2

329-333

EN

In this work, the experimentally determined changes of internal damping of magnesium alloy AZ31 and the relative changes of the elastic modulus are presented. The changes of internal damping for the basic material in the temperature range 30-450 C were measured. Increase of the damping properties of magnesium alloy AZ31 about high temperatures is caused by the movement of the binary point defects activated by the temperature during the solidification of the dendritic structure.

10

Wstępna analiza numeryczna procesu walcowania poprzeczno-klinowego odkuwek ze stopu magnezu AZ31

Pater Z.

Hutnik, Wiadomości Hutnicze

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2009

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Vol. 76, nr 8

641-643

PL

W artykule podano wybrane wyniki analiz numerycznych procesu walcowania poprzeczno-klinowego (WPK) wyrobów ze stopu magnezu gatunku AZ31. Obliczenia wykonano metodą elementów skończonych w warunkach przestrzennego stanu odkształcenia, przy uwzględnieniu zjawisk cieplnych zachodzących w trakcie kształtowania. W szczególności przedstawiono progresję kształtu odkuwki w trakcie walcowania oraz mapy odkształceń i temperatur. Uzyskane rezultaty obliczeń wskazują na przydatność WPK w kształtowaniu wyrobów osiowosymetrycznych ze stopu magnezu AZ31.

EN

The results of numerical analysis of cross-wedge rolling (CWR) process of parts from AZ31 magnesium alloy are presented in this paper. Calculations were made using finite element method under the condition 3-D state of strain taking into consideration thermal phenomena during the forming process. Shape progression of workpiece during rolling, strain and temperature fields are presented in the paper in details. Obtained results show usability of CWR process for forming axi-symmetrical AZ31 magnesium alloy part.

11

Microstructure of magnesium alloy AZ31 after low-speed extrusion

Skubisz P., Skowronek T., Sińczak J.

Metallurgy and Foundry Engineering

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2007

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Vol. 33, no. 2

113-120

EN

Direct extrusion of magnesium alloy AZ31 and changes in microstructure resultant from low-speed small-reduction extrusion are presented. The results show possibilities of grain refinement and improvement of mechanical properties associated with limited amount of generated deformation heat in aspect of using as-extruded material as a forging stock.

PL

Praca przedstawia wyniki prób wyciskania współbieżnego stopu AZ31, obrazujące zmiany zachodzące w mikrostrukturze po wyciskaniu z małym stopniem przerobu oraz małymi prędkościami. Ukazują one szerokie możliwości rozdrobnienia ziarna oraz towarzyszącą im poprawę własności materiału spowodowaną ograniczeniem ilości generowanego ciepła odkształcenia w aspekcie zastosowania wyciskanych prętów jako wsadu do kucia matrycowego.