Browsing by Subject "mechanical properties"

Now showing 1 - 20 of 40

Access status: Open Access ,
A Characterization of the Impact Toughness of Hot-rolled HSLA Steel
(AGH University Press, 2024) Hamryszczak, Tomasz; Śleboda, Tomasz; Lypchanskyi, Oleksandr; Pańcikiewicz, Krzysztof
Due to the wide use of HSLA steels in difficult conditions, e.g. at low temperatures, it is extremely important to test the impact strength of these steels. This is equally important because most of those structures are made by welding these steels, and the welding process itself has a significant impact on the properties of joints and welding zones. In this work, the authors analyzed two selected representative HSLA steels rolled in the Krakow branch of ArcelorMittal Poland S.A. – the only place in Poland where HSLA steels in the form of hot-rolled strips can be produced on an industrial scale. Impact tests were performed in accordance with technical acceptance standards, and then the fracture surfaces after impact tests were characterized using light and scanning microscopy. In the next part of the work, a set of previously gathered data were analyzed to determine the influence of thermomechanical rolling process parameters on the level of impact strength and the influence of chemical composition on it.
Access status: Open Access ,
AA2024/fly ash lightweight composites fabricated by powder metallurgy
(2024) Nikiel, Piotr
The paper presents the experimental results on the fabrication of lightweight aluminum alloy AA2024 matrix composites reinforced with fly ash microspheres using powder metallurgy (PM) via hot pressing. The primary aim was to achieve a composite with the highest possible matrix density while preserving undamaged microspheres. A mixture of powders consisting of AA2024 alloy powder and 10 wt% fly ash was pressed at 550°C and pressures of 5, 10, 20, and 30 MPa for two minutes. The obtained composites had densities in the range of 1.93 - 2.31 g/cm3. Microstructural analysis revealed uniform distribution of the fly ash microspheres in the aluminum alloy matrix. The hardness of the composites was comparable only between the samples pressed at 10, 20, and 30 MPa, falling within the range of 118 to 122 HV0.1. The sample pressed at 5 MPa exhibited significantly lower hardness of 98.8 HV0.1. The composites produced by pressing at 20 and 30 MPa were characterized by high yield strength and compression strength, ranging from 211 to 216 MPa and 300 to 354 MPa, respectively. The composites pressed applying lower pressures, especially those at 5 MPa, exhibited significantly lower values of plastic yield strength and compression strength, with values of 109 MPa and 115 MPa, respectively. Taking into account the density, the number of damaged microspheres, and the microstructure of the AA2024/fly ash composite, the optimal pressing range is between 10 - 20 MPa, but superior mechanical properties were achieved after pressing at 20 and 30 MPa.
Access status: Open Access ,
Al 6082 and Al 7075 alloys under the modified low-cycle fatigue test
(2016) Maj, Maria; Piekło, Jarosław
This paper discusses the possibility of assessing the quality of materials in terms of their mechanical properties as determined by a modified low-cycle fatigue test applied in these studies. The developed computer program adapted to the needs of an MTS universal testing machine is described, as are the details of an algorithm used by this program. The compatibility of test results obtained by the two methods (i.e., the standard low-cycle fatigue test [LCF] and its modified original version [MLCF]) has been demonstrated on the samples of selected non-ferrous metals alloys.
Access status: Open Access ,
Allowable strain as an indicator of fatigue life
(2011) Maj, Maria
Fatigue life, allowable strain and different data on the fatigue resistance of metals and alloys are of great importance for the designer. Knowledge of this subject is very important, given the complicated nature of its impact on many factors, starting with the specific properties of different alloys and in the conditions of their operation ending. This is the reason why, in many cases, the aforementioned complex nature of the effect may remain unknown, which can result in too high values of the safety factors adopted in calculations and, conseąuently, in excessive enlargement of the weight of individual parts of the machinery and equipment, especially as regards the cast elements. In this publication to evaluate the effort (fatigue life), the equivalent strain calculated by the aforementioned method directly from the results of the strain measurements was compared with the permissible strain limit, determined from the results of an MLCF fatigue test. Detailed analysis of the obtained results enables us to claim that permissible strain limit can be regarded as an indicator of the fatigue life.
Access status: Open Access ,
Analysis of stability levee during different flooding wave stages
(Wydawnictwa AGH, 2016) Dwornik, Maciej; Franczyk, Anna; Krawiec, Krzysztof
The stability of levee depends mainly on mechanical and hydromechanical properties of material used for its construction.
Access status: Open Access ,
Badania właściwości mechanicznych stali do produkcji dyskowych narzędzi urabiających dla górnictwa
(2008) Herezy, Łukasz
The disc cutting tools used in the past in longwall shearer has been withdrawn because of extremely high dynamic loading of its elements. Several positive aspects of these solutions are still topic of both theoretical and experimental works which are possible thanks a tremendous progress in thermal and chemise-thermal treatment of the steel. The paper presents results of multi variant investigations made at the laboratory of »Celsa« Steel Work, which have to help in receiving material with needed properties. The results of the research have to improve knowledge about construction of new machines for mining industry.
Access status: Restricted ,
Badanie przydatności kruszyw dla potrzeb budownictwa drogowego
(Data obrony: 2016-07-14) Kiecana, Monika Zofia
Wydział Geologii, Geofizyki i Ochrony Środowiska
Kruszywa są stosowane jako podstawowy materiał w budownictwie drogowym. Ich właściwości mechaniczne wpływają na jakość drogi oraz na bezpieczeństwo ruchu drogowego. Przydatność kruszyw określana jest na podstawie badań laboratoryjnych. Do najważniejszych zalicza się badanie mrozoodporności, odporności na ścieranie i polerowanie oraz wysadzinowości. Uzyskane wyniki pozwalają ocenić możliwość wykorzystania kruszywa do wykonania warstw nawierzchni drogowej, nasypów i wykopów oraz pozostałych elementów konstrukcyjnych.
Access status: Restricted ,
Badanie właściwości mechanicznych akrylanowych cementów kostnych modyfikowanych poliuretanowymi materiałami fazowo-zmiennymi
(Data obrony: 2017-01-25) Czwórnóg, Justyna
Wydział Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej
Access status: Restricted ,
Bioaktywne kompozyty ceramiczne z udziałem bioszkieł żelowych i ceramiki fosforanowo-wapniowej
(Data obrony: 2018-07-04) Majewska, Magdalena
Wydział Elektrotechniki, Automatyki, Informatyki i Inżynierii Biomedycznej
Access status: Open Access ,
Changes of some of the mechanical properties of rocks and rock mass in conditions of mining exploitation and mine workings flooding
(2012) Bukowski, Przemysław; Bukowska, Mirosława
Eksploatacja górnicza powoduje wpływy w obrębie górotworu, które przejawiają się jego destrukcją i odwodnieniem. Procesy te oddziałują na właściwości skał górotworu powodując ich zmianę, zmianę stanu zagrożeń naturalnych i warunków prowadzenia robót górniczych. Odwadnianie górotworu prowadzi do wzrostu wartości parametrów wytrzymałościowych skał, które ponownie mogą się zmniejszyć na przykład. pod wpływem nasycania ich wodą w procesie zatapiania wyrobisk górniczych. W artykule przedstawiono współzależności zmian warunków geomechanicznych i hydrogeologicznych zachodzących w górotworze pod wpływem eksploatacji górniczej. Na tle wyników porównawczych badań laboratoryjnych i polowych wykonanych przed i po przejściu frontu eksploatacyjnego, scharakteryzowano zmiany wytrzymałości na ściskanie skał znajdujących się w strefie wpływów podbierania i nadbierania pokładu. W nawiązaniu do zmian sytuacji górniczej w GZW po 1945 roku scharakteryzowano zmiany w warunkach hydrogeologicznych i ich wpływ na warunki geomechaniczne w otoczeniu wyrobisk górniczych. Zasygnalizowano znaczenie zmian warunków hydrogeologicznych i geomechanicznych dla prawidłowego wykonywania ocen warunków bezpiecznego prowadzenia robót górniczych.
Access status: Open Access ,
Comparison among different constitutive equations on investigating tensile plastic behavior and microstructure in austempered ductile iron
(AGH University of Science and Technology Press, 2018) Angella, Giuliano; Zanardi, Franco
The capabilities of different constitutive equations of approximating the tensile flow curves and correlating plastic behavior with the microstructure were investigated in austempered ductile iron ADI 1050. In a previous paper, the microstructure evolution of ADI 1050 during austempering was investigated through quenching the ADI 1050 after 14 increasing austempering times to room temperature. The 14 samples were tensile tested and two classes of constitutive equations were examined in the present paper. The Hollomon-type constitutive equations approximated all of the tensile flow curves of ADI 1050 very well but failed in correlating the plastic behavior with microstructure evolution. Voce-type constitutive equations approximated the tensile flow curves only at high stresses very well but could correlate the plastic behavior with the microstructure evolution of ADI 1050 during austempering excellently. The reason of this success was rationalized in terms of the physical basis of Voce-type equations, while Hollomon-type equations are empirical.
Access status: Open Access ,
Comparison of impact of immersed and micro-jet cooling during quenching on microstructure and mechanical properties of hypoeutectic silumin AlSi7Mg0.3
(Wydawnictwa AGH, 2017) Czekaj, Edward; Kwak, Zofia; Garbacz-Klempka, Aldona
This article presents research the results of the mechanical properties at the ambient temperature of hypoeutectic cast silumin EN AC-AlSi7Mg0.3 (according to EN 1706:2011, analogic to alloy A356 according to AA - the Aluminum Association). As related to the commonly known and used process of immersion during quenching, the research also used a micro-jet system of cooling. After quenching, the experimental samples were also submitted to artificial aging in three different variations. The achieved results were compared with the mechanical properties of the alloy in the as-cast state. Samples from the experimental alloy were subjected to micro-jet cooling during quenching, in principle, they had a similar level of properties as related to the samples that were cooled by immersion, only in some cases did the micro-jet cooling give better results. Further works in the field should be aimed at constructing machines for micro-jet cooling with water pressure levels significantly higher than the typical pressure of community waterworks.
Access status: Open Access ,
Computer modelling of the ablation casting process and prediction of the strength properties of AC-42000 castings
(Wydawnictwa AGH, 2022) Małysza, Marcin; Puzio, Sabina; Major-Gabryś, Katarzyna; Głowacki, Mirosław; Wilk-Kołodziejczyk, Dorota; Kamińska, Jadwiga
The demand for castings with superior properties has compelled the development and optimization of manufacturing technologies. By further developing already known techniques, we are able to contribute to the introduction of new research possibilities. The article presents the methodology of conducting simulation tests of the gravity casting process into sand moulds with the use of ablation. The ablation technique consists in spraying water through evenly spaced nozzles onto a mould into which the liquid casting alloy has been poured. The conducted research focuses on an alloy from the group of Al-Si alloys. In order to compare the effects of different techniques, additional tests were carried out for gravity casting into sand and metal die moulds. At the same time, virtual experiments were conducted to develop a simulation methodology for ablation casting technology, taking into account mould degradation. Additionally, the possibility of predicting the final mechanical properties of various manufacturing technologies was tested. Destructive tests were carried out to determine the mechanical properties in the cast samples, as well as microstructure tests and secondary dendrite spacing. The results of the mechanical tests are compared with the predicted simulation properties.
Access status: Open Access ,
Considering semi-crystallinity in molecular simulations of mechanical polymer properties - using nanoindentation of polyethylene as an example
(Wydawnictwa AGH, 2021) Fritz, Susanne
Molecular dynamic (MD) simulations have been used to investigate the response of semi-crystalline polymers in nanoindentation tests, using polyethylene (PE) as an example. To that purpose, semi-crystalline simulation boxes of linear PE with various chain lengths up to C2000 were created by homogeneous nucleation during the non-isothermal cooling of melts. The final crystallinity depended on the chain length and the cooling rate used and could be estimated using various parameters like density, fraction of bonds in trans conformation, and energy terms. The simulation boxes were transferred into surface models and subjected to nanoindentation tests using non equilibrium MD. This allowed the deformation behaviour of the material to be analysed directly. Strong dependencies on the crystallinity of the PE were found, which underlines the importance of considering crystallinity when investigating the mechanical properties of semi-crystalline polymers by means of simulations.
Access status: Open Access ,
Correlation between mechanical properties of selected 7xxx series aluminum alloys obtained by semi-continuous casting
(2016) Kwak, Zofia; Garbacz-Klempka, Aldona; Perek-Nowak, Małgorzata; Szymański, Łukasz
The studied ingots were made of alloys with a similar zirconium ratio, typically be given as: EN AW--7010 [AlZn6MgCu] and EN AW-7003 [Al Zn6Mg0,8Zr], in accordance with European standard PN-EN 573-3:2014-02 English version. The symbols S and K are our internal modifications, compatible with the standard. The added zirconium was intended to improve the tensile strength resulting from plastic forming and an increasing resistance to cracking. Samples were taken from ingots made in the process of semi-continuous casting, some of which were homogenized, however, non-homogenized samples were also analyzed. The tests of tensile strength for the 7003, 7003S, and 7010K alloys were conducted longitudinally and transversely to the casting direction.The tensile strength test for 7010 was conducted only transversely to the direction of casting. The aim of this publication is to present the results of strength test sand to show a correlation between the basic properties of 7xxx-series aluminum alloys, i.e., relative elongation E, yield strength YS, and ultimate tensile strength UTS.
Access status: Open Access ,
Design of new casting alloys of Al-Mg-Si-Mn system with alloying additions, its structure, and mechanical properties
(Wydawnictwa AGH, 2017) Bojko, Vìctorìâ; Czekaj, Edward; Warmuzek, Małgorzata; Mihalenkov, Kostântin Vìktoroviĉ
The strength of Al-Mg-Si-Mn casting alloy strongly depends on Mg content in solid solution and precipitation of strengthening phases. Alloys with the nominal composition AlMg5Si2Mn with addition of Li and Ti+Zr were studied by means of differential scanning calorimetry (DSC), transmission electron microscopy (TEM) and energy dispersive X-Ray analysis (EDX). DSC measurements show that the eutectic melting temperature was about 595°C and it is higher than that of commercial A356 casting alloy. The macro- and microhardness tests show that in as-cast state hardness were higher than for A356 and continuously growth during artificial aging. TEM investigations reveal that during artificial aging three different precipitation types are forms in the alloy matrix. Two of them belong to the different structures of Mg?Si precipitates. Appearance of the third one identified as d'-Al?Li phase represent that Al-Mg-Si system can be successfully used for designing of Li-containing casting alloy which is not developed yet.
Access status: Open Access ,
Determining mechanical properties and material models of subsoil for buildings in mining areas
(2012) Florkowska, Lucyna; Walaszczyk, Jan; Maj, Agnieszka
Zawarta w artykule problematyka związana jest z wyznaczaniem wpływu eksploatacji górniczej na obiekty budowlane przy zastosowaniu metod modelowania numerycznego. Narzędzia symulacji numerycznych stosowane są w analizie współpracy budynku z deformującym podłożem m.in. w celu opracowania szczegółowej prognozy oddziaływania robót górniczych. Warunkiem prawidłowego przeprowadzenia tego rodzaju analizy jest rzetelne rozpoznanie warunków górniczych, geologicznych i konstrukcyjnych. W pracy przedstawione zostały zagadnienia związane z modelowaniem podłoża obiektu w aspekcie wyznaczania oddziaływań górniczych, rozpoznania warunków posadowienia i przyjęcia modelu materiałowego. W tym zakresie scharakteryzowano procesy deformacyjne zachodzące w podłożu wskutek oddziaływania eksploatacji, omówiono ogólnie zagadnienie sporządzania prognozy wpływów eksploatacji górniczej na powierzchnię, przytoczono wymagania dotyczące rozpoznania podłoża obiektów posadowionych na terenach górniczych oraz wymieniono ważniejsze metody tego rodzaju rozpoznania. Koncentrując się następnie na zagadnieniach związanych z opracowaniem szczegółowej analizy oddziaływania eksploatacji zaproponowano zastosowanie modelowania numerycznego, jako narzędzia tego typu analiz. Pod tym kątem przedstawiono przykłady doboru prawa materiałowego podłoża oraz wyznaczenia wartości jego parametrów. Przykłady te dotyczą dwóch materiałów geologicznych: gliny piaszczystej oraz piaskowca. Dla każdego z nich omówiono zakres przeprowadzonych badań laboratoryjnych, przytoczono wyniki oraz przedstawiono wybrane prawo materiałowe z wyznaczonymi wartościami parametrów. Przedstawiona została także analiza wpływu wartości podstawowych parametrów mechanicznych podłoża: modułu sprężystości podłużnej, i współczynnika Poissona na rozkład naprężeń pod ławą fundamentową.
Access status: Open Access ,
Effect of grain refinement on mechanical properties of microalloyed steels
(2006) Muszka, Krzysztof; Majta, Janusz; Bienias, Łukasz
The goal of the present work was to study the effect of grain size and strain rate on the mechanical properties of microalloyed steels. The range of the microstructures was developed and their mechanical properties were measured under quasi-static conditions. The influence of different thermomechanical parameters on grain refinement, and thus, on final mechanical behavior of these steels seems to be very important issue, because of their application as the materials with both high strength and ductility. There is a clear lack of understanding of the role of intermediate ultrafine microstructures on the mechanical response of structural steels, which is important as this is the refinement level most likely to be achieved under industrial processes. The main scope of this research includes the development of thermomechanical treatments to produce ultra fine-grained steels with enhanced properties. These materials will be developed for the application in many industries (e.g. automotive industry, shipbuilding), and in any commercial applications where very good properties and good-quality construction materials are of paramount importance. The results of this work will allow to systematically correlate the evolution of deformation microstructure and the deformation mechanisms operating in fine-grained materials during processing. This work will also be directed towards understanding the specific strengthening mechanisms by which the plastic deformation leads to a refined grain size.
Access status: Open Access ,
Effect of Titanium Alloying of Zn-Al-Cu Alloys for High Pressure Die Casting in Production Conditions
(AGH University Press, 2023) Pasierb, Łukasz; Łakomski, Jan; Figurski, Krzysztof
The paper presents the possibility of the industrial production of Zn4Al3Cu alloy with the addition of 0.41% Ti. Tests are described on the manner of introducing the ZnTi2 master alloy to the alloy, so that the chemical composition of the desirable elements proportion is obtained. The chemical persistence of the Zn4Al3CuTi was determined as low in the conditions of the long heating of the alloy before casting. Tests on the microstructure and mechanical properties of the obtained alloys were also conducted. The strength of the die-cast Zn4Al3Cu alloy was 265 MPa and, when measured on samples taken from the high pressure die-cast, it reached 369 MPa. It was determined that the addition of titanium to the Zn4Al3Cu alloy causes significant refinement of the structure and contributes to the formation of intermetallic phases.
Access status: Open Access ,
Features of 2017A and AlSi9Mg aluminum alloys friction stir welded with root-side heating
(2016) Mroczka, Krzysztof; Pietras, Adam; Jura, Jerzy
Aluminum alloys 2017A and AlSi9Mg (hypo-eutectic silumin) were friction stir welded with a relatively high linear velocity (over 1 m/min) and use of an additional heat source from the root side of the weld. Macrostructure investigation (with high-resolution images) showed no effect of heating on weld quality. The welding process caused significant fragmentation of the secondary phases in the AlSi9Mg alloy. Furthermore, it was proven that the material above the weld nugget was not mixed and contained micro-defects that were not caused by welding. Also, it contained cavities on the boundaries between Si-particles and the matrix. Based on hardness distribution, a slight strengthening of the cast alloy was observed at the bottom and middle parts of the weld. However, the hardness of the 2017A alloy initially decreased and then increased due to natural aging. This means that the FSW process produced a metastable state in the alloy.