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1

The effect of geometry on mechanical properties of Ti6Al4V ELI scaffolds manufactured using additive manufacturing technology

Szymczyk Patrycja, Hoppe Viktoria, Ziółkowski Grzegorz, Smolnicki Michał, Madeja Marcin

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 1

144--156

EN

Owing to the possibility of direct processing of CAD models into three-dimensional objects, additive manufacturing (AM) is widely used in the production of individualized bone scaffolds that can lead to perfect restoration of anatomical structures of missing bone tissues. In this work, one of the AM technologies was applied, referred to as Electron Beam Melting (EBM), using Ti6Al4V ELI alloy to produce open-cell structures. Scaffold architecture influences its mechanical properties and is important from the point of view of biological considerations. To optimize mechanical properties, designed geometries were subjected to Finite Element Method analysis and experimental static compression tests. Also, geometric CT analysis of manufactured scaffolds was carried out (geometry deviations up to ± 300 µm). Obtained results have shown that AM can be used to produce Ti6Al4V ELI alloy scaffolds displaying mechanical parameters similar to those of bone tissue (E = 0.45–2.88 MPa). The EBM process affects the microstructure and macrostructural properties of manufactured parts, e.g., through internal porosities present in the material by to unmelted powder particles (internal porosity in range of 1.25–2.25%). To assess the quality and suitability of additively manufactured implants, a multidimensional verification of the impact of the manufacturing process on the properties of the final product was performed.

2

Influence of ultrasound assist during hot air drying on properties of dried apple crisps

Banaszak J., Pawłowski A.

Chemical and Process Engineering

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2018

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Vol. 39, nr 3

263–-270

EN

In this paper the influence of high power airborne ultrasound on drying biological material (Lobo apple) properties is considered. Apple samples were dried convectively at 75 ◦C and air flow of 2 m/s with and without ultrasound assist at 200W. During experiments, sun-drenched and not sun-drenched part of fruits were considered separately to show, how the maturity of the product influences dry material properties. Dried apple crisps in a size of small bars were subjected to compression tests during which acoustic emission (AE) was used. Analysis of AE and strength test results shows that correlations between received acoustic signals and sensory attributes (crispness, brittleness) of dried apples can be found. It was noted that ultrasound improved fruit brittleness in comparison with pure convective processes, where fruit maturity determines a kind of destruction and behaviour of dried apple crisps.

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Assessment of collapse diagrams of rigid polyurethane foams under dynamic loading conditions

Linul E., Serban D. A., Marsavina L., Sadowski T.

Archives of Civil and Mechanical Engineering

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2017

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Vol. 17, no. 3

457--466

EN

This paper investigates the collapse diagrams (energy-absorption and efficiency diagrams) under dynamic compression tests (drop tests) with an impact loading speed of 3.09 m/s. Experimental tests were carried out at room temperature on seven different types of closed-cell rigid polyurethane foams with densities of 40, 80, 100, 120, 140, 145 and 300 kg/m3 respectively. Based on the measured load–displacement curves, authors plotted the variation of peak stress, energy-absorption and efficiency attributes with respect to density for each type of foam, highlighting the optimum foam density (100 kg/m3). The influence of density and loading direction (in-plane and out-of-plane) on the main mechanical properties are also discussed. Following the investigations it was observed that both efficiency and energy absorption diagrams shows similar results, leading to the conclusion that both methods are reliable. Considering the test setup, a finite element analysis model was developed that aimed to replicate the experimental procedures. Simulations were performed in the commercial software Abaqus/Explicit using the implemented Elastic/Crushable foam constitutive model and using the static and dynamic test data for calibration. The energy-absorption and efficiency diagrams obtained from simulations were compared with the experimental data.

4

Analysis of the Deformability of Two-Layer Materials AZ31/Eutectic

Mola R., Mróz S., Szota P., Sawicki S.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 4

3017--3022

EN

The paper present the results of physical simulation of the deformation of the two-layered AZ31/eutectic material using the Gleeble 3800 metallurgical processes simulator. The eutectic layer was produced on the AZ31 substrate using thermochemical treatment. The specimens of AZ31 alloy were heat treated in contact with aluminium powder at 445°C in a vacuum furnace. Depending on the heating time, Al-enriched surface layers with a thickness of 400, 700 and 1100 μm were fabricated on a substrate which was characterized by an eutectic structure composed of the Mg17Al12 phase and a solid solution of aluminium in magnesium. In the study, physical simulation of the fabricated two-layered specimens with a varying thickness of the eutectic layer were deformed using the plane strain compression test at various values of strain rates. The testing results have revealed that it is possible to deform the two-layered AZ31/eutectic material at low strain rates and small deformation values.

PL

W pracy przedstawiono wyniki modelowania fizycznego odkształcania materiału dwuwarstwowego AZ31/eutektyka z wykorzystaniem symulatora procesów metalurgicznych Gleeble 3800. Warstwę o strukturze eutektyki wytworzono na podłożu ze stopu magnezu w gatunku AZ31 metodą obróbki cieplno-chemicznej. Próbki ze stopu AZ31 wygrzewano w kontakcie z proszkiem aluminium w temp. 445°C w piecu próżniowym. Zależnie od zastosowanego czasu wygrzewania uzyskano na podłożu magnezowym warstwy wzbogacone w aluminium o grubościach 400, 700, 1100 μm i strukturze eutektycznej składającej się z fazy międzymetalicznej Mg17Al12 oraz roztworu stałego aluminium w magnezie. W ramach symulacji fizycznych otrzymane dwuwarstwowe próbki o różnych grubościach warstwy eutektyki odkształcano stosując próbę ściskania w płaskim stanie odkształcenia przy różnych prędkościach odkształcenia. Otrzymane wyniki badań wskazują na możliwość odkształcania dwuwarstwowego materiału AZ31/eutektyka z małymi prędkościami odkształcenia oraz przy stosunkowo małych wartościach odkształcenia.

5

The Portevin –Le Chatelier Effect and Acoustic Emission of Plastic Deformation CuZn30 Monocrystals

Ozgowicz W., Grzegorczyk B., Pawełek A., Piątkowski A., Ranachowski Z.

Archives of Metallurgy and Materials

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2014

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Vol. 59, iss. 1

183--188

EN

The paper presents the investigation of the relation between the acoustic emission (AE) and instability of plastic deformation type Portevin-Le Chatelier (PLC) of single-phase brass CuZn30 monocrystals with crystallographical orientation [13 9]. The monocrystals have been investigated applying the method of free compression at a constant strain rate and the temperature within the range from 200°C to 400°C, simultaneously recording PLC phenomenon by means of acoustic emission. During hot axial compression tests the correlation between work-hardening curves σ - ε, which display PLC effect and characteristic of acoustic emission signals has been found. Moreover, it was proved that in the range of the PLC effect, the acoustic signal is an impulse a character of cyclic repeatability, distinctly correlated qualitatively with the stress oscillations on the curves σ - ε. The analysis of the obtained results leads to the conclusion that in the tested monocrystals the effect PLC is probably controlled by complex processes similar to the phenomenon of dynamic strain ageing (DSA), which are described by diffusion models.

PL

Streszczenie W pracy badano zależność między emisją akustyczną (EA), a niestabilnością odkształcenia plastycznego typu Portevin Le Chatelier monokryształów jednofazowego mosiądzu CuZn30 o orientacji krystalograficznej [13 9]. Monokryształy poddano próbie swobodnego ściskania przy stałej prędkości odkształcenia w zakresie temperatury od 200°C do 400°C stosując jednocześnie pomiar emisji akustycznej. Określono zależność pomiędzy przebiegiem krzywych umocnienia σ - ε wykazujących efekt PLC. a charakterystyką sygnałów emisji akustycznej generowanych w badanej próbie ściskania jednoosiowego. Stwierdzono, że w zakresie występowania efektu PLC podczas próby ściskania, sygnał EA ma charakter impulsu cyklicznego, wyraźnie skorelowany jakościowo z oscylacjami naprężeń na krzywych σ - ε. Analiza uzyskanych wyników pozwala przypuszczać, że w badanych monokryształach efekt PLC jest kontrolowany prawdopodobnie przez złożone procesy podobne do zjawisk starzenia dynamicznego po zgniocie (DSA), które są opisane modelami dyfuzyjnymi.

6

Investigation of thermomechanical properties of ferromagnetic NiFega shape memory alloy subjected to pseudoelastic compression test

Pieczyska E., Dutkiewicz J., Masdeu F., Luckner J., Maciak R.

Archives of Metallurgy and Materials

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2011

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Vol. 56, iss. 2

401-408

EN

In the study stress-induced reversible phase transformation in NiFeGa magnetically controlled shape memory alloy subjected to pseudoelastic compression test was investigated. The specimen's mechanical characteristics and temperature changes related to the exothermic martensite transformation and endothermic reverse transformation were measured in contact-less way by using a fast and sensitive infrared camera (IR). It was found that the stress-induced phase transformation process occurs in this alloy in heterogeneous way, since the observed specimen's temperature distribution was not uniform. Stress-strain curves obtained for the first, as well as for the subsequent six loading-unloading compression cycles and their related temperature changes, elaborated as average from the specimen's surface, were analyzed. It was concluded that the stress and the temperature changes developing in the subsequent cycles depend on the applied test conditions, however the highest discrepancies were observed between the first and the second cycles of the compression loading.

PL

W pracy przedstawiono wyniki badań zmian parametrów mechanicznych oraz temperatury stopu Ni54Fe19Ga27, wykazującego magnetyczną pamięć kształtu. Próbki stopu poddawano procesowi pseudosprężystego ściskania. Temperaturę mierzono za pomocą szybkiej kamery termowizyjnej. Stwierdzono, że indukowana naprężeniem przemiana fazowa zachodzi w tym stopie w sposób niejednorodny, a przebieg charakterystyk mechanicznych i zmian temperatury w kolejnych cyklach obciążania i odciążania prówbki zależy od zastosowanej metodyki badawczej.

7

Microstructure forming processes of the 26Mn-3Si-3Al-Nb-Ti steel during hot-working conditions

Dobrzański L. A., Borek W.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 40, nr 1

25-32

EN

Purpose: The influence of hot-working conditions on microstructure evolution of new-developed 26Mn-3Si-3Al-Nb-Ti high-manganese steel was investigated. Design/methodology/approach: The force-energetic parameters of hot-working were determined in continuous and multi-stage compression test performed in temperature range of 850 to 1100°C using the Gleeble 3800 thermomechanical simulator. Evaluation of processes controlling work-hardening were identified by microstructure observations of the specimens compresses to the various amount of deformation (4x0.29, 4x0.23 and 4x0.19). Findings: The investigated steel is characterized by high values of flow stresses from 250 to 430 MPa. Increase of flow stress along with decrease of compression temperature is accompanied by translation of ĺmax strain in the direction of higher deformation. Results of the multi-stage compression proved that applying the true strain 4x0.29 gives the possibility to refine the austenite microstructure as a result of dynamic recrystallization. In case of applying the lower deformations 4x0.23 and 4x0.19, the process controlling work hardening is dynamic recovery and a deciding influence on a gradual microstructure refinement has statical recrystallization. Research limitations/implications: To determine in detail the microstructure evolution during industrial rolling, the hot-working schedule should take into account real number of passes and higher strain rates. Practical implications: The obtained microstructure – hot-working relationships can be useful in the determination of power-force parameters of hot-rolling and to design a rolling schedule for high-manganese steel sheets with fine-grained austenitic structures. Originality/value: The hot-deformation resistance and microstructure evolution in various conditions of hot-working for the new-developed high-manganese 26Mn-3Si-3Al-Nb-Ti austenitic steel were investigated.

8

Processes forming the microstructure evolution of high-manganese austenitic steel in hot-working conditions

Dobrzański L. A., Borek W.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

397-407

EN

Purpose: The aim of the paper is to characterise the microstructure evolution of new-developed 27Mn-4Si-2Al-Nb-Ti high-manganese steel in various conditions of hot-working. Design/methodology/approach: Flow stresses during the multistage compression test were measured using the Gleeble 3800 thermo-mechanical simulator. To describe the hot-working behaviour, the steel was compressed to the various amount of deformation (4x0.29, 4x0.23 and 4x0.19). The microstructure evolution in successive stages of deformation was determined in metallographic investigations using light, scanning and electron microscopy as well as X-ray diffraction. Findings: The steel has austenite microstructure with annealing twins and some fraction of ĺ martensite plates in the initial state. The flow stresses are much higher in comparison with austenitic Cr-Ni and Cr-Mn steels and slightly higher compared to Fe-(15-25) Mn alloys. The flow stresses are in the range of 200-400 MPa for the applied conditions of hot-working. Making use of dynamic and metadynamic recrystallization, it is possible to refine the microstructure and to decrease the flow stress to 350 MPa during the last deformation at 850°C. Applying the true strains of 0.23 and 0.19 requires the microstructure refinement by static recrystallization. After the grain refinement due to recrystallization, the steel is characterised by uniform structure of ă phase without ĺ martensite plates. Research limitations/implications: To fully describe the hot-working behaviour of the new-developed steel, further investigations in wider temperature and strain rate ranges are required. Originality/value: The hot-deformation resistance and microstructure evolution in various conditions of hot-working for the new-developed high-manganese 27Mn-4Si-2Al-Nb-Ti austenitic steel were investigated.

9

Effect of isothermal bainitic transformation temperature on retained austenite fraction in C-Mn-Si-Al-Nb-Ti TRIP-type steel

Grajcar A., Krztoń H.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 35, nr 2

169-176

EN

Purpose: The aim of the paper is to determine the influence of isothermal bainitic transformation temperature on a fraction of retained austenite for a new-developed C-Mn-Si-Al-Nb-Ti TRIP-type steel. Design/methodology/approach: The thermo-mechanical processing was realized in a multi-stage compression test by the use of the Gleeble 3800 thermomechanical simulator. The steel was subjected to six variants of processing with an isothermal bainitic transformation temperature in a range from 250 to 500°C. Identification of phase composition was achieved using microstructure observations and X-ray diffraction. To determine the fraction of retained austenite the Rietveld method was applied. Findings: The maximum fraction of retained austenite equal up to 16% can be obtained for the temperatures of isothermal bainitic transformation from 400 to 450°C, while the maximum carbon content in the ă phase equal 1.5 wt.% is present at the temperature of 350°C. Below 350°C due to high Ms temperature, the largest grains of retained austenite located in the ferritic matrix transform to marteniste. In a temperature range from 350 to 450°C, the Msă temperature has a negative value, stabilizing the retained austenite. Research limitations/implications: To determine in detail the influence of isothermal bainitic transformation conditions on a fraction of retained austenite, the knowledge of the effect of isothermal holding time is also important. Practical implications: The obtained microstructures and especially retained austenite fraction dependent on an isothermal bainitic transformation temperature can be useful in optimization of thermo-mechanical processing conditions of C-Mn-Si-Al TRIP-type steels. Originality/value: Combined colour etching and X-ray diffraction methods were applied for microstructure identification of modern group of TRIP steels predicted to use in the automotive industry.