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1

Application of X-S Control Cards to Parameter Control in the Machining Process of Piston Castings for Internal Combustion Engines

Krępa Adam, Piątkowski J.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 4

116--120

EN

This article discusses the possibility of using a two-track X-S control card on a Mesas device to control the production process parameters of piston castings for combustion engines. The research was carried out at the Federal-Mogul Gorzyce company. The basis for estimating the variability of the process results from the mean value (X) is the standard deviation (S). Thanks to specially designed measuring stations that use algorithms to calculate process indicators (Cp and/or Cpk) and their visualization, the cost of manufacturing products and the number of non-compliant products (scraps) are reduced. The process stability was investigated by measuring the key dimensions of the piston casting in a specific population and a given measurement cycle. Taking into account the precision of details, their technical condition, and surface quality, the production machines and cutting tools were optimally selected. It has been found that an important element of the effective use of Statistical Process Control (SPC) are trained/experienced operators who can correctly interpret the resulting control chart forms.

2

Projektowanie stopów o wysokiej entropii

Lachowska M., Gradoń P., Piątkowski J.

Rudy i Metale Nieżelazne Recykling

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2018

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R. 63, nr 10

3--7

PL

Artykuł przedstawia przegląd rozwoju strategii i metod używanych w badaniach na temat stopów o wysokiej entropii. Jest to nowa grupa materiałów, która może być scharakteryzowana poprzez nowoczesne podejście do kompozycji stopowych. Podczas, gdy w tradycyjnych stopach można wyróżnić jeden lub dwa podstawowe elementy, których stężenie jest bardzo wysokie w stosunku do innych pierwiastków stopowych, w stopach o wysokiej entropii pięć lub więcej pierwiastków stopowych dodaje się w równych lub prawie równych proporcjach. Od dawna uważano, że ten rodzaj kompozycji doprowadzi do kruchej konglomeracji związków międzymetalicznych, ale stwierdzono, że wysoka entropia losowych stałych roztworów może je uprzywilejowywać względem innych uporządkowanych, fazowych lub międzymetalicznych związków, prowadząc do prostej jednofazowej struktury. To odkrycie stworzyło nowe, ogromne możliwości projektowania nowych materiałów, ale także konieczność przyjrzenia się istniejącym metodologiom rozwoju stopów.

EN

Paper presents a review of development strategies and methods used in research on high entropy alloys. This is a new group of materials which can be characterised by novel approach to alloy composition. Whereas in traditional alloys we can distinguish one or two base elements whose concentration is very high in relation to other alloying elements, in high entropy alloys five or more alloying elements are added in equal or near equal proportions. It has been long thought that this type of composition will lead to brittle conglomeration of intermetallics, but it was found that high entropy of random solid solutions can preferentiate them over other, ordered, phases or intermetallic compounds leading to simple single phase structure. This discovery created new and vast possibilities for designing new materials, but also necessitated revision of existing methodologies for alloy development.

3

Identyfikacja wad odlewniczych tłoków silnikowych metodami zarządzania jakością

Piątkowski J., Czerepak M.

Rudy i Metale Nieżelazne Recykling

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2018

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R. 63, nr 12

9--13

PL

W artykule przedstawiono możliwości zastosowania wykresu Pareto-Lorenza, diagramu Ishikawy i metody 5Why do identyfikacji głównych przyczyn wad materiałowych odlewów tłoków silnikowych. Metody "leanowskie" użyto w celu ograniczenia negatywnego zjawiska o największej częstotliwości występowania, a tym samym przyczyn generowania największych kosztów związanych z reklamacjami jakościowymi odlewów dla przemysłu motoryzacyjnego. Stosując metodę "od szczegółu do ogółu" w układzie 6M-3 kategorie przyczyn wad, zaproponowano kierunki usprawniające.

EN

he paper presents the possibilities of using the Pareto-Lorenzo diagram, the Ishikawa diagram and the 5Why method to identify the main causes of material defects in engine piston castings. "Lean" methods were used to limit the negative phenomenon with the highest frequency of occurrence, thus the reasons for generating the largest costs related to quality complaints of automotive cast industry. Using the "from the detail to the general" method in the 6M-3 system, the categories of defect causes, improvement directions were proposed.

4

Influence of Modifications on Fatigue Strength of AlSi17Cu5Mg(Fe) Alloy Used for Pistons for Internal Combustion Engines

Piątkowski J., Wieszała R.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

135--141

EN

Technological progress in construction of automotive vehicles, particularly in construction of engines, enforces simultaneous changes in foundry properties of aluminum alloys used in automotive industry. Until recently, abrasion resistance was the main usability criterion of a material used for pistons for internal combustion engines. At present however, because of the complexity of the process of the fuel mixture combustion, more restrictive standards of limited hydrocarbon emission, and the pursuit of reduction of the vehicle’s mass, fatigue strength of silumins enjoys a continuously increasing interest. The paper presents results of a computer simulation using the finite element method (FEM) and a real fatigue test of AlSi17Cu5Mg(0.5Fe) (A390.0) alloy with unilateral variable bending. The tests aimed to simulate a deflection of a combustion engine piston in a cylinder barrel were carried out in two variants: for a non-modified alloy and an alloy modified with CuP10 master alloy. Based on the distribution of stresses according to the Huber-Mises-Hencky theory (for a given range of the deflection from 0.1 to 0.3 mm), Wöhler curve was determined for the studied alloy. Based on on microstructural investigations, cracks of primary Si crystals were found, caused by fatigue changes resulting from unilateral pulsating vibrations.

5

Ocena toksyczności mieszanin gazowych z okolic szybu sg-2 KGHM Polska Miedź S.A. w aspekcie uciążliwości zapachowej dla lokalnej społeczności

Bachowski C., Janicka A., Piątkowski J., Skrętowicz M., Zawiślak M.

Przegląd Górniczy

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2017

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T. 73, nr 1

13--19

PL

Zgłaszany przez mieszkańców gminy Jerzmanowa problem uciążliwości zapachowej w okolicach szybu SG-2 budzi zaniepokojenie zgłaszających, nie tylko w aspekcie wpływu emitowanych gazów na jakość środowiska, ale przede wszystkim w zakresie potencjalnie niekorzystnego wpływu na zdrowie. W artykule przedstawiono wyniki pracy badawczej realizowanej przez Politechnikę Wrocławską na zlecenie KGHM, której celem było wykonanie oceny toksyczności mieszanin gazowych z okolicy szybu SG2 w korelacji z określeniem stężenia zapachowego, subiektywnymi odczuciami mieszkańców gminy Jerzmanowa oraz badaniami modelowymi. Na podstawie przeprowadzonej pracy stwierdzono, że stopień toksyczności gazów emitowanych z szybu SG2 (w testach in vitro, metodą BAT-CELL®) określa się od słabego i umiarkowanego (w przypadku referencyjnej linii komórkowej nabłonka płuc ludzkich A549) po średni (w przypadku referencyjnej linii komórkowej tkanki podskórnej myszy L929), co może wskazywać na większe powinowactwo gazów w stosunku do negatywnego wpływu na skórę niż na drogi oddechowe) oraz, że emitowane gazy z szybu SG2 nie wykazują charakteru toksycznego w imisji, w przypadku obu linii komórkowych, w badanych punktach zidentyfikowanych jako najbardziej narażone na działanie gazów pochodzących z emitora.

EN

The reported odour problem in Jerzmanowa district, where SG-2 exhaust shaft is located, concerns local citizens especially in the health aspect. The paper presents the results of the researches, provided by Wroclaw University of Technology for KGHM POLSKA MIEDŹ S.A., which are aimed at the evaluatation the gaseous mixture toxicity in emission (SG-2 shaft) and immision (Jerzmanowa district area) in correlation with the measured odours intensity, subjective feelings of local citizens and emitted substances distribution. The researches results indicate that toxicity level of gaseous mixtures emitted directly from the SG-2 shaft (based on In vitro tests delivered thanks to innovative BAT-CELL® method) ranges from low (A549 – standard human lung cells line) to medium (L929 – standard mouse skin cells line). What is important – the mixture of gases in immision (area of Jerzmanowa district) is not toxic in any tested location, despite the fact that citizens feelings indicato that the odour problem exists.

6

Surface topology of friction pairs of A390.0 alloys

Wieszała R., Piątkowski J., Stanik Z., Roszak M., Pakieła W.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 82, nr 2

58--62

EN

Purpose: In the paper, geometric structure of the surface of A390.0 alloy, manufactured using various methods are presented, in combination with EN-GJL-350 cast alloy, which corresponds to parameters used in combustion engines. Design/methodology/approach: Alloy after a modification with CuP10 master alloy and overheating to 920°C for 30 min was analysed, and the results were compared with those of the material without overheating. Roughness studies allowed for defining the influence of technological history on the wear parameters of the alloy. Findings: Analysis of result shows that all investigated properties were improved. Significant differences between the analysed materials were proved during the analysis of friction coefficient and surface topography of wear track. Research limitations/implications: The application of modified by CuP10 aluminium alloy allows to improve parameters such as friction coefficient and wear rate. This property’s causes that this new modified material can be used in many applications where the aim is to reduce friction coefficient as well as wear rate. Practical implications: Improvement the tribological properties as well as reducing the coefficient of friction makes these materials may be used in many applications in the automotive industry such as engine cylinder, engine blocks, etc.. Originality/value: Influence of aluminium modification on chosen tribological properties and friction coefficient have been investigated.

7

The Application of ATD and DSC Methods to Study of the EN AC-48000 Alloy Phase Transformations

Piątkowski J., Przeliorz R., Szymszal J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

207--211

EN

Tests concerning EN AC 48000 (AlSi12CuNiMg) alloy phase transition covered (ATD) thermal analysis and (DSC) differential scanning calorimetry specifying characteristic temperatures and enthalpy of transformations. ATD thermal analysis shows that during cooling there exist: pre-eutectic crystallization effect of Al9Fe2Si phase, double eutectic and crystallization α(Al)+β(Si) and multi-component eutectic crystallization. During heating, DSC curve showed endothermic effect connected with melting of the eutectic α(Al)+β(Si) and phases: Al2Cu, Al3Ni, Mg2Si and Al9Fe2Si being its components. The enthalpy of this transformation constitutes approx. +392 J g-1. During freezing of the alloy, DSC curve showed two exothermal reactions. One is most likely connected with crystallization of Al9Fe2Si phase and the second one comes from freezing of the eutectic α(Al)+β(Si). The enthalpy of this transformation constitutes approx. –340 J g-1. Calorimetric test was accompanied by structural test (SEM) conducted with the use of optical microscope Reichert and scanning microscope Hitachi S-4200. There occurred solution's dendrites α(Al), eutectic silicon crystal (β) and two types of eutectic solution: double eutectic α(Al)+β(Si) and multi-component eutectic α+AlSiCuNiMg+β.

8

Selected Tribological Properties of A390.0 Alloy

Wieszała R., Piątkowski J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

175--178

EN

Emergence of new designs for internal combustion engines resulted in a necessity to search for new materials which will rise to excessive technological requirements under operating conditions of modern internal combustion engines of up to 150 kW. Focusing only on material properties, theoretically existing alloys should meet presents requirements. More importantly, existing materials are well fitted to the entire crank-piston system. Thus, there is a need for a more thorough examination of these materials. The paper presents studies on determination of coefficient of friction μ and wear for the A390.0 alloy modified with AlTi5B master alloy combined with EN GJL-350 cast iron. The characteristics of a T-11 tribological tester (pin on disc) used for the tests, as well as the methodology of the tribological tests, were described. Also, the analysis of the surface distribution of elements for the pin and the disc was presented. The studies were realized in order to find whether the analyzed alloy meets the excessive requirements for the materials intended for pistons of modern internal combustion engines. The results show that the A390.0 alloy can only be applied to a load of 1.4 MPa. Above this value was observed destructive wear, which results in the inability to use it in modern internal combustion engines.

9

Risk Assessment of Defect Occurrences in Engine Piston Castings by FMEA Method

Piątkowski J., Kamiński P.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 3

107--110

EN

The FMEA (Failure Mode and Effects Analysis) method consists in analysis of failure modes and evaluation of their effects based on determination of cause-effect relationships for formation of possible product or process defects. Identified irregularities which occur during the production process of piston castings for internal combustion engines were ordered according to their failure rates, and using Pareto-Lorenz analysis, their per cent and cumulated shares were determined. The assessments of risk of defects occurrence and their causes were carried out in ten-point scale of integers, while taking three following criteria into account: significance of effects of the defect occurrence (LPZ), defect occurrence probability (LPW) and detectability of the defect found (LPO). A product of these quantities constituted the risk score index connected with a failure occurrence (a so-called “priority number,” LPR). Based on the observations of the piston casting process and on the knowledge of production supervisors, a set of corrective actions was developed and the FMEA was carried out again. It was shown that the proposed improvements reduce the risk of occurrence of process failures significantly, translating into a decrease in defects and irregularities during the production of piston castings for internal combustion engines.

10

Resistance of WE43 and ZRE1 Magnesium Alloys to Gas Corrosion

Przeliorz R., Piątkowski J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 2

217--221

EN

In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment). At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in humidified gas.

11

Application of FEM Analysis for Evaluation of the Stress and Deformation Distributions in the Top Layer of A390.0 Alloy During Friction

Wieszała R., Piątkowski J., Bąkowski H.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 1

228--234

EN

The paper presents an analysis of the effect of shape of primary silicon crystals on the sizes of stresses and deformations in a surface layer of A390.0 alloy by Finite Elements Method (FEM). Analysis of stereological characteristics of the studied alloy, performed based on a quantitative metallographic analysis in combination with a statistical analysis, was used for this purpose. The presented simulation tests showed not only the deposition depth of maximum stresses and strains, but also allowed for determining the aforementioned values depending on the shape of the silicon crystals. The studied material is intended for pistons of internal combustion engines, therefore the analysis of the surface layer corresponded to conditions during friction in a piston-cylinder system of an internal combustion engine having power of up to 100 kW. The obtained results showed important differences in the values of stresses and strains up to 15% between various shape of the silicon crystals. Crystals with sharp edges caused higher stresses and deformation locally than those with rounded shapes.

12

Application of DSC Method in Studies on Phase Transitions of Ni Superalloys

Przeliorz R., Piątkowski J.

Archives of Foundry Engineering

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2017

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Vol. 17, iss. 4

133--136

EN

The paper presents results of calorimetric studies of foundry nickel superalloys: IN100, IN713C, Mar-M247 and ŻS6U. Particular attention was paid to determination of phase transitions temperatures during heating and cooling. The samples were heated to a temperature of 1500°C with a rate of 10°C min–1 and then held at this temperature for 5 min. After a complete melting, the samples were cooled with the same rate. Argon with a purity of 99.99% constituted the protective atmosphere. The sample was placed in an alundum crucible with a capacity of 0.45 cm3. Temperature and heat calibration was carried out based on the melting point of high-purity Ni. The tests were carried out by the differential scanning calorimetry (DSC) using a Multi HTC high-temperature calorimeter from Setaram. Based on the DSC curves, the following temperatures were determined: solidus and liquidus, dissolution and precipitation of the γ’ phase, MC carbides and melting of the γ’/γ eutectic. In the temperature range of 100-1100°C, specific heat capacity of the investigated superalloys was determined. It was found that the IN713C and IN100 alloys exhibit a higher specific heat while compared to the Mar-M247 and ŻS6U alloys.

13

Badanie procesu krystalizacji stopu AlSi9Cu3(Fe) metodą analizy termicznej ATD

Gontarczyk A., Piątkowski J., Mikuszewski T.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 5

201--204

PL

Analiza termiczna znajduje szerokie zastosowanie m.in. do oceny przebiegu procesu krystalizacji stopów i prognozowania ich właściwości użytkowych. Szczególnie dotyczy to metody ATD, której możliwości interpretacyjne reakcji cieplnych są szerokie i dotyczą m.in. wyznaczenia ciepła przemian fazowych, oceny efektów procesu modyfikacji oraz obecności w stopie różnych zanieczyszczeń, które zwiększają zakres krzepnięcia stopu. W pracy przedstawiono wyniki badań krzepnięcia siluminu AlSi9Cu3 (Fe) metodą analizy termicznej ATD. Wyznaczono charakterystyczne temperatury krystalizacji (Tliq., TE, TE (Me), Tsol.) stopu bazowego i po modyfikowaniu zaprawą AlSr10 oraz przedstawiono przykłady mikrostruktury badanego stopu. Warunki przepływu ciepła w przyjętym układzie wpływają na postać struktury, m.in. na wielkość ziarna osnowy oraz stopień rozdrobnienia składników strukturalnych (eutektyki), co ma duże znaczenie w kształtowaniu właściwości użytkowych i jakości odlewów stosowanych w różnych gałęziach przemysłu.

EN

The thermal analysis has wide application, for example in evaluation of the crystallization process of the alloys, and forecasting their use properties. It is especially applicable for ATD method, which interpretation abilities of the heat reactions are wide and applicable for defining the phase transition's heat, evaluation of modification process occurrence and presence of contaminants in the alloy, which extends the crystallization scope of the alloy. In the paper the result of the A/5i9Cu3 fFe) silumin solidifying study with the thermo analysis ATD has been shown. The characteristic crystallization temperatures has been defined (T , Te T£IMer Tsol)for the base alloy, and after modification with AlSrW mortar, also the examples of microstructure of the tested alloy has been shown. The defining of the heat flow conditions in the assumed system has the influence of the structure, for example on the grain size of the warp and fragmentation level of the structural components (eutectics), what has substantial influence on the use properties and on the quality of the castings used in the industry.

14

Application of selected lean manufacturing methods for deficit identification in combustion engine piston casts

Kuczyńska-Chałada M., Piątkowski J., Kamiński P., Gontarczyk A.

Rudy i Metale Nieżelazne Recykling

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2016

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R. 61, nr 6

254--258

EN

The article presents the selected Lean Manufacturing (LM) methods the application of which contributed to identification of casting deficits in the production process of engine pistons. Improvement of the quality of production process of piston casts made of alloy EN AC-AlSi12CuNiMg (EN AC-48000) will lower costs, increase scrap participation and, especially, will positively influence the image of a selected casting enterprise. During the production process, each stage is loaded with many factors influencing the final product quality, for this reason, it can be stated that in order to implement the LM principles in the enterprise, a few techniques included in this concept must be applied [1, 2, 3]. The basis of LM system are, e.g.: 5S method, Just in Time, Kanban, Kaizen, TQM, 5 Why [4]. Due to the nature of piston production (combination of manual and automatic actions), the human factor and machine park failure frequency also is the problem of the multi-stage process, which results in the fact that indicating a universal model of application of Lean concept is very difficult.

PL

W artykule przedstawiono wybrane metody Lean Manufacturing (LM), których stosowanie przyczyni się do identyfikacji wad odlewniczych w procesie produkcyjnym tłoków silnikowych. Poprawa jakości procesu produkcyjnego odlewów tłoków ze stopu EN AC-AlSi12CuNiMg (EN AC-48000) obniży koszty, zmniejszy udział wybraków, a zwłaszcza wpłynie pozytywnie na wizerunek wybranego przedsiębiorstwa odlewniczego. Podczas procesu produkcyjnego każdy etap jest obarczony wieloma czynnikami wpływającymi na jakość produktu końcowego. Chcąc sprawdzić, czy w przedsiębiorstwie wdrożono zasady LM, trzeba w organizacji procesu produkcyjnego odnaleźć kilka technik wchodzących w skład tej koncepcji [1, 2, 3]. Podstawami systemu LM są: metoda 5S, Just in Tme, Kanban, Kaizen, TQM, 5 Why [4]. Ze względu na specyfike produkcji tłoków (połaczenie czynności wykonywanych ręcznie i automatycznie), problemem wieloetapowego procesu jest także czynnik ludzki i awaryjność parku maszynowego, co sprawia że wskazanie uniwersalnego modelu stosowania koncepcji Lean jest bardzo trudne.

15

Using probabilistic automata for security protocols verification

Siedlecka-Lamch O., Kurkowski M., Piątkowski J.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 2

119--125

EN

The article discusses the issues of modeling and the analysis of executions, which is a substantial part of modern communication protocols - authentication protocols, which are generally referred to herein as security protocols. The article presents a way of security protocols executions analysis with the use of probabilistic automata, without well known and widely used perfect cryptography assumption (we assume allowing the possibility of breaking a key with a specified probability). This type of analysis leads to interesting observations about the operation of the protocol and its weaknesses.

16

The visualization of shaft vibration using the algorithm of phase-amplitude data interpolation

Piątkowski J.

Journal of Applied Mathematics and Computational Mechanics

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2016

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Vol. 15, nr 1

137--148

EN

In many cases of observations of phenomena and physical processes we use data measured in multidimensional spaces. However, in practice, for the economic or technical reasons, we cannot obtain equally numerous data sets for all dimensions. In this case we can say that we are trying to assess or classify this process by using a few parts of its projection. For processing and computing of an input data a different solutions of interpolation and/or approximation are often used. But data, which have phase-amplitude nature, should be treated in a specific way. The lack of proper interpretation of phase shifts in many cases can result in obtaining the significant distortions of an analyzed process image. In this paper the algorithm of phase-amplitude interpolation is presented. This algorithm has been used for creating the contours charts, as projections of rotating shaft vibrations, in transient operating conditions of the machine.

17

Influence of manufacturing technology on tribological properties of A390.0 alloy

Wieszała R., Piątkowski J., Roszak M., Pakieła W.

Journal of Achievements in Materials and Manufacturing Engineering

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2016

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Vol. 77, nr 1

13--17

EN

Purpose: In this paper, results of tribological studies on AlSi17Cu5Mg alloy subjected to a modification (CuP10) and a significant overheating above Tliq are presented, referring them to the starting material. Design/methodology/approach: The influence of the applied technologies on the refinement of the primary crystals of Si was defined by determination of stereological parameters. In case of the overheated alloy, the primary crystals of silicon assume the forms of polygons with sharp edges after the overheating. In practice, it results in a decrease in tribological properties and an increase in the coefficient of friction in relation to the alloy modified with phosphorus. Findings: The result show that all investigated properties were changed. Significant differences between the analyzed specimens were proved in the friction coefficient and in the wear rate of the tested friction connections. Research limitations/implications: The application of modified by CuP10 aluminum alloy allows to reduce the friction coefficient between tested surface and counter-samples and also reduce the wear rate. This property’s causes that this material can be used in many applications where the aim is to reduce friction coefficient and wear rate. Practical implications: Reducing of friction coefficient and increase wear resistance causes that these materials can be used in many applications in the automotive industry such as blocks of engines, cylinders etc. Originality/value: Influence of aluminium modification on chosen tribological properties have been investigated.

18

Tribological Properties of AlSi17Cu5Mg Alloy Modified with CuP Master Alloy with Various Speeds of Friction

Piątkowski J., Wieszała R.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 1

45--48

EN

The paper presents the influence of modification with phosphorus (CuP10) on the tribological properties of the alloy AlSi17Cu5Mg coupled abrasively with cast-iron EN GJL-350. Tests of coefficient of friction and wear of mass were conducted on tribological tester T-01. An important aspect in the assessment of the tribological properties is the analysis of initial material microstructure in reference to silumin which underwent modification with phosphorus. It was found that the difference in structure of tested materials, mainly sizes of primary silicon crystals significantly influences the tribological properties whereas the speed change of the friction knot does not have such big influence.

19

The Study of Phase Transformations of AlSi9Cu3 Alloy by DSC Method

Piątkowski J., Przeliorz R., Gontarczyk A.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 4

109--112

EN

With the use of differential scanning calorimetry (DSC), the characteristic temperatures and enthalpy of phase transformations were defined for commercial AlSi9Cu3 cast alloy (EN AC-46000) that is being used for example for pressurized castings for automotive industry. During the heating with the speed of 10ºC∙min-1 two endothermic effects has been observed. The first appears at the temperature between 495 ºC and 534 ºC, and the other between 555 ºC and 631 ºC. With these reactions the phase transformation enthalpy comes up as +6 J g-1 and +327 J g-1. During the cooling with the same speed, three endothermic reactions were observed at the temperatures between 584 ºC and 471 ºC. The total enthalpy of the transitions is – 348 J g-1. Complimentary to the calorimetric research, the structural tests (SEM and EDX) were conducted on light microscope Reichert and on scanning microscope Hitachi S-4200. As it comes out of that, there are dendrites in the structure of α(Al) solution, as well as the eutectic (β) silicon crystals, and two types of eutectic mixture: double eutectic α(Al)+β(Si) and compound eutectic α+Al2Cu+β.

20

The Reasons of Steam Pipeline Elbow Rupture

Mesjasz A., Piątkowski J.

Archives of Foundry Engineering

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2016

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Vol. 16, iss. 3

67--70

EN

In the paper the reasons for steam pipeline’s elbow material rupture, made of steel 13CrMo4-5 (15HM) that is being used in the energetics. Based on the mechanical properties in the ambient temperature (Rm, Rp0,2 and elongation A5) and in the increased temperature (Rp0,2t) it was found, that the pipeline elbow’s material sampled from the ruptured area has lower Rp0,2t by around 2% than it is a requirement for 13CrMo4-5 steel in it’s base state. The damage appeared as a result of complex stress state, that substantially exceeded the admissible tensions, what was the consequence of considerable structure degradation level. As a result of the microstructure tests on HITACHI S4200 microscope, the considerable development of the creeping process associates were found. Also the advances progress of the microstructure degradation was observed, which is substantial decomposition of bainite and multiple, with varied secretion size, and in most cases forming the micro cracks chains. With the use of lateral micro sections the creeping voids were observed, that creates at some places the shrinkage porosities clusters and micro pores.