Wyniki wyszukiwania - BazTech

1

Wpływ uziarnienia i współczynnika miażdżenia kruszywa na właściwości stwardniałego betonu

Akram Amanda, Słowik Marta

Materiały Budowlane

|

2023

|

nr 11

41--45

PL

Przeprowadzono badania eksperymentalne w celu szerszej analizy wpływu uziarnienia i współczynnika miażdżenia (ACV) kruszywa żwirowego, dolomitowego i granitowego na właściwości stwardniałego betonu. Nie stwierdzono istotnego wpływu ACV na wytrzymałość betonu na ściskanie i na rozciąganie, przy dwóch różnych maksymalnych wymiarach ziaren. Moduł sprężystości był bardziej zależny od uziarnienia i wytrzymałości kruszywa.

EN

The experimental investigation was carried out to analyse in depth the effect of grain size and aggregate crushing value (ACV) of gravel, dolomite and granite aggregate on properties of hardened concrete. No significant effect of ACV on the compressive and the tensile strength of concrete was noticed, for two different maximum grain sizes whereas the modulus of elasticity was more dependent on the aggregate granulation and strength.

2

Electrochemical corrosion of aluminium alloy AA1050, processed by accumulative roll bonding

Ilieva M. D., Radev R. H.

Archives of Materials Science and Engineering

|

2023

|

Vol. 124, nr 1

5--13

EN

Purpose: To investigate the changes in corrosion behaviour of severely deformed by accumulative roll bonding aluminium alloy AA1050. Design/methodology/approach: To determine the influence of the accumulative roll bonding on microstructure, texture, and grain size, electron backscattered diffraction was used. Corrosion behaviour was evaluated in a 3.5 wt.% sodium chloride water solution using anodic polarisation. Findings: It was found out that accumulative roll bonding up to eight cycles led to an increase in corrosion rate compared to annealed alloy, but the increase in the number of cycles of accumulative roll bonding from two to eight shows a tendency toward lowering corrosion rates. It has a beneficial influence on pitting corrosion susceptibility. Research limitations/implications: The presented research focuses only on the influence of texture and grain size on severely deformed aluminium alloy AA1050 corrosion. Other factors, such as accumulated during deformation stresses, could also play their role in the corrosion process. Originality/value: The paper reports results on the influence of two factors – texture and grain size, on the corrosion of severely deformed aluminium alloy AA1050. Most reports on the topic include only the influence of texture or grain size.

3

The analysis of the structure and the hardness of TIG-welded joints made of nickel superalloy Inconel 600

Górka Jacek, Kik Tomasz, Chruściel Marek, Jamrozik Wojciech, Kiel-Jamrozik Marta

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2022

|

Vol. 66, No. 4

37--44

EN

The tests discussed in the article aimed to analyse the structure and hardness of the heat affected zone and that of the weld in thin butt joints (1.0 mm) made of nickel superalloy Inconel 600 using the TIG method and variable welding linear energy restricted within the range of 45 J/mm to 80 J/mm. The test joints were subjected to visual tests, macro and microscopic metallographic tests, scanning electron microscopy-based structural observations and hardness measurements. The tests concerned with the effect of parameters applied during the TIG welding of butt joints made of 1.0 mm thick sheets (Inconel 600) in laboratory conditions revealed that the most favourable quality of the sheets was obtained when welding arc linear energy was restricted within the range of approximately 45 J/mm to 80 J/mm. An increase in linear energy within the above-presented range led to an increase in the width of the weld and that of the HAZ (observed in the joints subjected to macroscopic metallographic tests). In addition, an increase in linear energy restricted within the aforesaid range increased the grain size in matrix γ (in the HAZ) from approximately 120 μm to approximately 200 μm. The structure of the weld contained the zone of columnar grains oriented towards the fusion line as well as large groups of primary grains having the dendritic structure with clearly visible axes of primary dendrites of varied orientation. In addition, the weld structure also contained precipitates in the form of low-melting eutectics located in interdendritic spaces. The X-ray microanalysis concerning fragments having an area of 0.045mm2, examined in the individual zones of the welded joints made of Inconel 600, revealed only slight differences in terms of mass and atomic concentrations of the primary chemical elements of the superalloy matrix such as nickel, chromium and iron or larger differences as regards carbide-forming elements such as niobium and titanium and the concentration of carbon itself.

PL

Celem badań była analiza struktury i twardości strefy wpływu ciepła oraz spoiny w złączach doczołowych blach cienkich (1,0 mm) wykonanych z nadstopu niklu typu Inconel 600 metodą TIG, przy zmiennej energii linowej spawania w zakresie 45–80 J/mm. Uzyskane złącza spawane poddano: badaniom wizualnym, badaniom metalograficznym makro- i mikroskopowym, obserwacjom struktury w elektronowym mikroskopie skaningowym oraz pomiarowi twardości. Przeprowadzone badania wpływu parametrów procesu spawania metodą TIG złączy doczołowych ze stopu Inconel 600 o grubości 1 mm spawanych doczołowo wykazały, że: złącza blach cienkich z badanego nadstopu w warunkach laboratoryjnych wykazują najlepszą jakość przy zachowaniu energii liniowej łuku w zakresie ok. 45–80 J/mm, wzrost energii liniowej spawania w stosowanym zakresie powoduje zwiększenie szerokości spoiny i SWC badanych makroskopowo złączy, zwiększenie energii liniowej łuku w procesie w zakresie 45–80 J/mm powoduje w SWC wzrost wielkości ziaren osnowy γ odpowiednio od ok. 120 μm do ok. 200 μm, struktura spoiny wykazuje mniej lub bardziej wyraźną strefę ziaren słupkowych zorientowanych do linii wtopienia oraz duże kolonie ziaren pierwotnych o budowie dendrytycznej z wyraźnie ujawnionymi osiami głównymi dendrytów o różnej orientacji oraz wydzieleniami w postaci eutektyk niskotopliwych w przestrzeniach międzydendrytycznych, wyniki mikroanalizy rentgenowskiej z obszarów o powierzchni 0,045 mm2 badanych w poszczególnych strefach złącz blach spawanych z nadstopu Inconel 600 wykazują niewielkie zróżnicowanie wartości masowego i atomowego stężenia podstawowych pierwiastków osnowy nadstopu takich, jak nikiel, chrom i żelazo oraz większe w przypadku stężenia pierwiastków węglikotwórczych, takich jak niob i tytan, a także stężenia samego węgla.

4

A study of grain size effect on radon exhalation rate and uranium content of a phosphate rock

Jabbade Meryame, Nachab Abdellatif, Nourreddine Abdel Mjid, Errami Ezzoura, Benjelloun Mohammed

Acta Geophysica

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2022

|

Vol. 70, no 6

2805--2812

EN

Assessment of the exhalation rate allows a classification of materials according to their potential risk of exposure to radon. The present study investigates the granulation effect on the radon exhalation rates from a phosphate sample. The phosphate sample was sieved into different grain size dimensions ranging from2 mm. The exhalation rate of each fraction was measured using the accumulation method. The radon exhalation rate was found to decrease with an increase in grain size above 0.125 mm. The influence of grain size on uranium content was also studied using the autoradiography method. The uranium concentration increased for the smallest grains (0.5 mm). The measured values of radon exhalation rates are under the limits reported worldwide.

5

Transformation of structure during friction stir welding

Vakulenko Igor Alex, Plitchenko Sergey, Kurt Bulent, Proydak Svetlana, Askerov Hangardas

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2021

|

z. 111

181--191

EN

In comparison with low carbon steels, there is increased interest in the use of aluminium-based alloys as materials for the manufacture of welded structures rolling stock of railway transport. During friction stir welding aluminium-based alloy, against the background of the analysis structural transformations, issues of development hardening processes are considered. Under conditions of existence, a temperature gradient at zone of weld formation, shown degree approximation alloy to the conditions of superplastic flow and influence from presence particles of the second phase on grain size of matrix is estimated. Evaluation of the separate influence grain size of matrix and state of solid solution at total hardness of the weld showed dependence of their contributions on temperature of hot plastic deformation. As the temperature of plastic deformation of alloy at area of the weld increases, contribution to the total hardness from grain size increase and on state of the solid solution decreases.

6

Investigation the effect addition of nano Al2O3 on microstructure of Yttria tetragonal Zirconia polycrystalline ceramic

Alshaibani I.J.

Archives of Materials Science and Engineering

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2021

|

Vol. 107, nr 2

49--55

EN

Purpose: This research aimed to prepare tetragonal zirconia polycrystals powder by coprecipitation method and study effects of addition of different amounts of nano Al2O3 (1, 2 and 4) wt.% on its microstructure and mechanical properties of (5Y-TZP) composite. Design/methodology/approach: The powder was uniaxial pressed at a pressure of 150 MPa and held for 60 s, and sintered at the 1500°C, held for two hours and then cooling down at 5°C/min to room temperature. Microhardness and fracture toughness tests were utilized to evaluate the mechanical properties of yttria tetragonal zirconia polycrystal composite. The microstructure has been observed using field emission scanning electron microscopy(FESEM). Findings: The results showed an addition of nano Al2O3 has a great influence on hardness and microstructure, the increase in Vicker's microhardness of composite samples with the increase in the nano Al2O3 wt.% and microstructure were characterized with homogeneous zirconia distribution, grain growth destruction with the increasing percentage of nano Al2O3. The most important influence is the enhancing of the densification process as the porosity decreased. The highest hardness and maximum fracture toughness were recorded at 4 wt.% nano Al2O3. Research limitations/implications: Ceramic matrix composites are developed to overcome the brittleness of ZrO2 and the low toughness of alumina by formation, a large difference of elastic behavior between matrix and particles(dispersion phase )which disturbs the stress field as a dislocation comes near a particle. Practical implications: Zirconia has mechanical properties similar to those of stainless steel. Yttria-stabilized tetragonal Zirconia (Y-TZP) is growing used in dentistry due to its good mechanical properties such as hardness and fracture toughness. Thus, controlling of microstructure by adding nanoalumina plays an important role in enhancing these properties. Originality/value: Study the adding bitty percentage from nano alumina on microstructure and mechanical properties of (5Y-TZP) ceramic.

7

Metodyka badań mikrostruktury i podstawowych własności węglików spiekanych

Tomiczek Błażej, Matula Grzegorz, Gołombek Klaudiusz

LAB Laboratoria, Aparatura, Badania

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2020

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R. 25, nr 1

26--30

8

Factor Analysis and Mathematical Modeling in Determining the Quality of Coal

Niedoba Tomasz, Pięta Paulina, Surowiak Agnieszka

Inżynieria Mineralna

|

2020

|

no. 1, vol. 1

151--160

EN

The separation of coal material of three types of coals originating from three various Polish hard coal mines (types 31, 34.2 and 35, according to Polish nomenclature, which were steam coal, semi-coking coal and coking coal) into particle size fractions and then into particle density fractions was done and then the following parameters were measured for each particle size-density fraction: combustion heat, ash contents, sulfur contents, volatile parts contents, analytic moisture. In this way a 7-dimensional vector of data was created. Using methods of factor analysis the important features of coal were selected, which decide about their membership to individual types. To evaluate the appropriateness of the applied method the Bartlett’s sphericity test as well coefficient of Kaiser-Mayer-Olkin (KMO) were used. To select important factors the Kaiser criterion and Cattell’s scree test were used. The obtained results were compared with the results obtained in previous works by means of observation tunnels method. The results showed which particular features are crucial to define the type of coal what is also important to select appropriate method of its enrichment. Furthermore, the construction of a mathematical model presenting the relations between these properties and particle size and density is presented. Because of the fact that particles of certain size or density may occur in neighboring fractions three sorts of relations were examined basing on regression analysis.The analysis was conducted for all three coal types. Because of the fact that the models contain various amounts of independent variables R2 coefficient, mean squared error (MSE) and Mallow’s statistics Cp were applied to evaluate and compare obtained results.

PL

Wykonano rozdział trzech typów węgla o różnych charakterystykach, pochodzących z trzech różnych kopalni węgla kamiennego w Polsce (typy 31, 34.2 oraz 35, według Polskich norm, którymi były węgiel energetycznym, pół-koksujący oraz koksujący) na klasy ziarnowe a następnie na frakcje gęstościowe. Dla każdej otrzymanej w ten sposób frakcji wielkościowo-gęstościowej zmierzono następujące parametry: ciepło spalania, zawartość popiołu, zawartość siarki, zawartość części lotnych, wilgotność analityczna. W ten sposób otrzymano siedmiowymiarowy wektor danych. Za pomocą analizy czynnikowej wybrano istotne cechy węgla, które decydują o jego przynależności do określonego typu węgla. Aby ocenić prawidłowość zastosowanej metody wykorzystano test sferyczności Bartletta oraz współczynnik Kaisera-Mayera-Olkina (KMO). Otrzymane wyniki porównano z wynikami otrzymanymi w poprzednich pracach, które uzyskano metodą tuneli obserwacyjnych. Wyniki pokazały, które cechy węgla są niezbędne do określenia typu węgla, co wpływa na dobór odpowiedniej metody jego wzbogacania. Ponadto, zaprezentowano model prezentujący relacje pomiędzy tymi cechami a wielkością i gęstością ziaren. Ponieważ ziarna określonej wielkości lub gęstości mogą występować w sąsiednich klasach lub frakcjach, wykonano trzy typy modeli, bazując na analizie regresji. Analiza została wykonana dla trzech typów węgli. Ponieważ modele zawierają różne ilości zmiennych niezależnych do oceny i porównania otrzymanych wyników zastosowano współczynnik determinacji R2, błąd średniokwadratowy (MSE) oraz statystykę Mallowa Cp.

9

Effects of Separated Fractions of FBC Bottom Ash on Selected Properties of Cement Mortars

Kledyński Zbigniew, Krysiak Łukasz

Civil and Environmental Engineering Reports

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2020

|

Vol. 30, no. 4

1--20

EN

This paper discusses the effects of partial replacement of cement with fluidized bed bottom ash on the properties of mortars. The analyzed ash samples originating from four Polish power plants were separated by grain size selection into fine and coarse-grained fractions. This process leads to a creation of derivative samples of differing physical properties and, partially, phase compositions, as tested in XRD and TG analyses. Despite its high water demand, the obtained fine-grained fraction has the potential for application in cement based composites as a reactive, pozzolanic additive. An acceptable activity index may be reached when the sulfate content is limited, implying benefits of combining the ash with low gypsum cements. The coarse-grained fraction is significantly less reactive, while a high silica and aluminate content is related to improved mechanical properties of the composite. It can, therefore, potentially be used as a quasi-inert additive or a substitute for sand.

10

Effect of grain size on the physicomechanical properties

Ossia C. V., Big-Alabo A., Ekpruke E. O.

Advances in Manufacturing Science and Technology

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2020

|

Vol. 44, nr 4

135--144

EN

In this study, locally available waste coconut (Cocos nucifera) shells (CSs) were investigated as possible replacement for asbestos-based brake pads. The CS-based brake pad was tested for its physicomechanical properties and compared with a commercial brake pad used as control sample. The results showed that (a) an improved interfacial bonding between the CS particles and the binder as the grain size decreases; (b) the 90 μm grain size sample had better physicomechanical properties than the control sample in all tests except the thermal conductivity and stability tests; and (c) the hardness, compressive strength, and density of the CS-based brake pad decreased with increasing grain size, whereas the absorption properties increased with increasing grain size. The study showed that further reduction of the grain size below 90 μm and matrix impregnation with metals of good thermal conductivity could provide significant improvements to properties of the CS-based brake pad.

11

Advantages of Small-Seeded Species in Forests : Win-Win for Temporal and Spatial Dispersal among Seeds in Rhododendron

Wang Haiyang, Lai Xiaohong, Zhang Yanru, Chen Hong

Polish Journal of Ecology

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2019

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Vol. 67, nr 1

17--32

EN

There is little consistent evidence for evolutionary associations from seed production to seedling fitness. In this study, 20 species of Rhododendron genus were selected from subtropical forests of southwest China; the life-history functional traits such as the seed size, seed number per twig, germination traits, dispersal and seedling survival were investigated, the ecological relationships among them were tested and the advantages of small-seeded species were discussed. The results show that the quantitative parameters of germination, such as the germination rate, potential, and index are positively correlated with seed number produced per stem, while temporal parameters, such as germination peak timing and duration are positively correlated with seed size. The two results indicate that different Rhododendron species with different seed sizes and relative seed number can deal with varying environments according to spatial dispersal or time dispersal, respectively, and the advantages of smaller seeds in the aspect of sprouting vigour, dispersal ability and seedling survival may lay the foundation for the establishment of small-seeded plants in the forest.

12

The influence of sintering technique on microstructure and properties of ZrO2/Al2O3 composite

Wojteczko Agnieszka, Wojteczko Kamil, Strzelecka Marta, Nam Tatyana, Jach Katarzyna, Rosiński Marcin, Bućko Mirosław M., Pędzich Zbigniew

Composites Theory and Practice

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2019

|

R. 19, nr 4

157--160

EN

The following paper presents the results of investigations on the microstructure and mechanical properties of sintered composites in the zirconia-alumina system, fabricated by various sintering techniques. The investigations were performed for a particulate composite consisting of two continuous ceramic phases - zirconia (TZP) and alumina (α-Al2O3), 50 vol.% each. Two different methods were used to produce the samples: pressureless sintering and the U-FAST technique. The microstructure of the obtained sintered composite samples was evaluated using a scanning electron microscope. In addition, the density of the sintered bodies, their hardness and fracture toughness were investigated to evaluate the mechanical properties. Based on the obtained results of the investigations, the influence of the sintering technique on the microstructure and mechanical properties of the sintered composites was determined.

PL

Niniejsza praca prezentuje wyniki badań mikrostruktury oraz właściwości mechanicznych spieków kompozytowych na bazie tlenku cyrkonu i tlenku glinu, otrzymanych różnymi technikami spiekania. Materiał wykorzystany do badań to kompozyt ziarnisty składający się z dwóch ciągłych faz ceramicznych - tlenku cyrkonu (TZP) i tlenku glinu (α-Al2O3), po 50% objętościowych każda. Próbki zostały wytworzone za pomocą dwóch różnych metod, tj. spiekania swobodnego oraz techniki U-FAST. Dokonano oceny mikrostruktury otrzymanych spieków kompozytowych za pomocą skaningowego mikroskopu elektronowego. Dodatkowo przeprowadzono badanie ich stopnia zagęszczenia oraz ich twardości i odporności na kruche pękanie w celu określenia właściwości mechanicznych. Na podstawie otrzymanych wyników określono wpływ techniki spiekania na mikrostrukturę spieków kompozytowych, a co za tym idzie na ich właściwości mechaniczne.

13

Autokatalityczna synteza proszku miedzi z zastosowaniem koloidu srebra jako katalizatora

Wojnicki M., Polański M., Rudnik E., Luty-Błocho M.

Rudy i Metale Nieżelazne Recykling

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2018

|

R. 63, nr 5

18--23

PL

Przeprowadzono badania redukcji jonów miedzi za pomocą formaldehydu. Proces autokatalityczny inicjowano przez dodatek nanocząstek srebra. Uzyskano globularne ziarna proszku miedzi, tworzące większe aglomeraty. Nie stwierdzono formowania się ziaren o budowie dendrytycznej. Wielkość cząstek proszku mieści się w zakresie 0,2-3,0 μm, przy czym udział procentowy dominującej frakcji ziarnowej zależy od stosunku stężenia jonów miedzi i katalizatora w układzie reakcyjnym.

EN

Reduction of copper ions with formaldehyde was investigated. The autocatalytic process was initiated by addition of silver nanoparticles. Globular grains of copper powder with tendency to agglomeration were obtained. No dendritic grains were formed. Particle size of the powder is in the range of 0.2-3.0 μm, with the percentage of the dominant particle fraction being determined by the concentration ratio of copper ions and the catalyst in the reaction system.

14

Influence of hot-reduction parameters on the steel austenite structure of a railway wheel

Vakulenko I., Bolotova D., Perkov O., Lisniak A.

Zeszyty Naukowe. Transport / Politechnika Śląska

|

2016

|

z. 93

141--148

EN

The formation of grain structures with boundaries similar to substructures is one of the factors contributing to grain refinement in hot-reduction carbon steel. At the forming of a rim, the slight cooling-down (100-150°С) of the surface volumes is sufficient to increase their strength characteristics. After that, an increase in the magnitude of the hot-hardening of metal in the central rim volumes will lead to the formation of a more uniform fine-grain austenite structure over the rim section.

15

The influence of ferrite particle size on the quality of the magnetic marker in shale gas hydraulic fracturing

Bogacki J., Zawadzki J.

Systemy Wspomagania w Inżynierii Produkcji

|

2016

|

z. 3 (15)

25--33

EN

The study analyzes the influence of particle size of magnetic ferrite on the possibility of using it, as a marker in magnetic prop pant during hydraulic fracturing. Based on a broad and accurate literature review, it was found, that the ferrite grain size can be one of the critical parameter conditioning the quality of the magnetic marker in shale gas hydraulic fracturing. Hence, the ferrite grain size determines greatly both the costs and efficiency of hydraulic fracturing.

PL

W pracy przeanalizowano wpływ wielkości ziarna ferrytu na możliwość zastosowania go, jako markera magnetycznego podczas szczelinowania hydraulicznego. Na podstawie szerokiego przeglądu dostępnej literatury, określono, że wielkość ziarna ferrytu może być kluczowym parametrem warunkującym jakość i właściwości markera magnetycznego stosowanego podczas szczelinowania hydraulicznego gazu łupkowego. Zatem, wielkość ziarna ferrytu wpływa zarówno na koszty jak i na efektywność szczelinowania hydraulicznego.

16

Investment casting parameters impact on IN 713C nickel-based superalloy microstructure

Roskosz S., Cygan R.

Inżynieria Materiałowa

|

2016

|

Vol. 37, nr 2

59--64

EN

The basic process for manufacturing of aircraft engine hot section elements made of nickel-based superalloys is investment casting using multilayer ceramic shell moulds. Introduction of new engines designs with higher thrust, lower fuel consumption and lower noise emissions enforce continual modification of casting materials, models, ceramic moulds, including melting, pouring and heat treatment processes parameters. The aim of this study was to determine the effect of pouring temperature and cobalt aluminate modifier in the subsurface layer of the mould on macrostructure of the IN 713C castings. The size of misruns, chill, columnar and equiaxed zones on the surface of the wedge castings is most affected by pouring temperature. Additionally it was proved that cobalt aluminate is an effective modifier of the IN713C superalloy causing not only refinement of equiaxed grains, but also reduction in the columnar grain size fraction.

PL

Nadstop niklu IN 713C jest stosowany między innymi na łopatki turbin silników lotniczych, odlewane precyzyjnie metodą traconego wosku w wielowarstwowych formach ceramicznych. Łopatki turbin często charakteryzują się gruboziarnistą i niejednorodną strukturą, która nie spełnia rygorystycznych wymagań dotyczących części wykorzystywanych w przemyśle lotniczym. Poprawę struktury łopatek wytworzonych z nadstopów niklu można uzyskać w wyniku odpowiedniego kształtowania wielkości ziarna w procesie odlewania. Ziarna o kontrolowanych rozmiarach można otrzymać dzięki odpowiedniej temperaturze zalewania, temperaturze formy i zastosowaniu modyfikatora w powierzchniowej warstwie formy odlewniczej. Celem badań było określenie wpływu temperatury zalewania oraz udziału modyfikatora CoAl2O4 w warstwie przypowierzchniowej formy odlewniczej na strukturę odlewów z nadstopu IN 713C.

17

Szacowanie trwałości zmęczeniowej stali z wykorzystaniem wielkości ziarna ferrytu

Owsiński R., Kamiński S., Niesłony A., Łagoda T.

Przegląd Mechaniczny

|

2015

|

nr 6

37--44

PL

W pracy przeprowadzono wnikliwe rozważania dotyczące zależności pomiędzy strukturą metalograficzną a trwałością zmęczeniową oraz zaproponowano związki matematyczne opisujące tę zależność. W niniejszej pracy przedstawiono metodę szacowania trwałości zmęczeniowej, opierającą się na budowie mikrostrukturalnej materiału z uwzględnieniem wielkości ziaren i udziału fazowego ferrytu i perlitu.

EN

In the paper insightful discussion of the relationship between the structure of metallographic and fatigue life was conducted and it proposes the mathematical relationships describing this relationship. This paper presents a method for estimating the fatigue life, based on the construction of the microstructural material taking into account the particle size and the participation of ferrite and pearlite phase.

18

Continuous extrusion of commercially pure titanium GRADE 4

Palan J., Taboada J. V., Kubina T., Malecek L., Hodek J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2015

|

Vol. 69, nr 1

33--37

EN

Purpose: Continuous extrusion of metals using Conform™ machine is used to introduce severe plastic deformation and to improve mechanical properties of metals by reducing their grain size. This paper describes a development of a continuous extrusion sequence for Ti grade 4 in the CONFORM 315i machine. Design/methodology/approach: The influence of material flow conditions on the surface quality of final extruded rods was analyzed with the FEM-based DEFORMTM software. Findings: During the development, several process parameters were varied, such as the die chamber temperature and the extrusion velocity. Research limitations/implications: The goal was to conduct the experiment at the lowest possible temperature in order to achieve a maximum strain hardening effect. The material’s mechanical properties and its flow through the die chamber were studied. The homogeneity of the material flow and the surface quality of final rods were then optimized. Originality/value: The effort led to improvements in the analytical model used in the FEM simulation so that the surface quality can now be optimized more efficiently.

19

The Effect Of Grain Size On The Mechanical Properties Of Aluminum

Jeong G., Park J., Nam S., Shin S.-E., Shin J., Bae D., Choi H.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1287--1291

EN

Although many studies have focused on the unique plastic deformation behavior of nanocrystalline aluminum (e.g., the positive deviation from Hall-Petch relation, the unusual yield-drop phenomenon in tensile mode, etc.), the data reported by different research groups are inconsistent with each other, possibly because of different fabrication processes. In this study, aluminum samples with a wide grain-size spectrum – from a few micrometers down to 100 nanometers – are manufactured by powder metallurgy. The grain size was measured by X-ray diffraction analysis and transmission electron microscope observation. Furthermore, the tensile behavior, which varied according to a grain size, is discussed with a comparison of the theoretical models.

20

Optimization of Laboratory Hot Rolling of Brittle Fe-40at.%Al-Zr-B Aluminide

Schindler I., Hadasik E., Kopeček J., Kawulok P., Fabík R., Opěla P., Rusz S., Kawulok R., Jabłońska M.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 3A

1693--1701

EN

Use of the protective steel capsules enabled to manage the laboratory hot flat rolling of the extremely brittle as-cast aluminide Fe-40at.%Al-Zr-B with the total height reduction of almost 70 %. The hot rolling parameters were optimized to obtain the best combination of deformation temperature (from 1160°C up to 1240°C) and rolling speed (from 0.14 m·s−1 to 0.53 m·s−1). The resistance against cracking and refinement of the highly heterogeneous cast microstructure were the main criteria. Both experiments and mathematical simulations based on FEM demonstrated that it is not possible to exploit enhanced plasticity of the investigated alloy at low strain rates in the hot rolling process. The heat flux from the sample to the working rolls is so intensive at low rolling speed that even the protective capsule does not prevent massive appearance of the surface transverse cracking. The homogeneity and size of product’s grain was influenced significantly by temperature of deformation, whereas the effect of rolling speed was relatively negligible. The optimal forming parameters were found as rolling temperature 1200°C and the rolling speed 0.35 m·s-1. The effective technology of the iron aluminide Fe-40at.% Al-Zr-B preparation by simple processes of melting, casting and hot rolling was thus established and optimized.

PL

Zastosowanie ochronnych stalowych kapsuł pozwoliło na przeprowadzenie laboratoryjnego walcowania na gorąco pasm z niezwykle kruchego odlewanego aluminidku żelaza (stopu na osnowie fazy międzymetalicznej) Fe-40at.%Al-Zr-B, które umożliwiło redukcję wysokości o prawie 70%. Parametry walcowania na gorąco były dostosowywane celem uzyskania korzystnego zakresu temperatury odkształcenia (od 1160°C do 1240°C) oraz prędkości walcowania (od 0.14 m·s−1 do 0.53 m·s−1) dla otrzymania pasma bez pęknięć i rozdrobnienia silnie niejednorodnej mikrostruktury odlewu. Zarówno eksperymenty jak i matematyczne symulacje oparte na MES wykazały, że niemożliwe jest uzyskanie dobrej plastyczności badanego stopu przy niskich prędkościach odkształcenia podczas walcowania na gorąco. Strumień ciepła płynący z próbki na walce jest tak intensywny przy małej prędkości walcowania, że nawet kapsuła ochronna nie zapobiega pojawieniu się powierzchniowych pęknięć poprzecznych. Jednorodność i rozmiar ziarn w materiale silnie zależy od temperatury odkształcenia, podczas gdy wpływ prędkości walcowania jest relatywnie niewielki. Optymalne parametry kształtowania stopu to: temperatura 1200°C oraz prędkość walcowania 0.35 m·s−1. Skuteczna technologia przygotowania aluminidku żelaza Fe-40at.%Al-Zr-B w prostym procesie topienia, odlewania i walcowania na gorąco została w ten sposób ustalona i zoptymalizowana.