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1
Content available Static and Dynamic Mechanical Properties of Nodular Cast Irons
Vaško A., Belan J., Tillová E.
Archives of Metallurgy and Materials
|
2019
|
Vol. 64, iss. 1
185--190
EN
Effects of charge composition on microstructure, mechanical and fatigue properties of nodular cast irons have been studied. For experiments, five melts of nodular cast iron were used – three types of unalloyed nodular cast irons (with different ratio of steel and pig iron in a charge and different additives for regulation of the chemical composition) and two types of alloyed nodular cast irons (SiMo- and SiCu- nodular cast iron). The microstructure of the specimens was evaluated according to a norm and by automatic image analysis. The mechanical properties were investigated by the tensile test, impact bending test and Brinell hardness test. The fatigue tests were carried out at sinusoidal cyclic push-pull loading at ambient temperature. The best mechanical properties were reached in the nodular cast iron alloyed by Si and Cu, what is related to its microstructure.
2
Content available Identification of Structural Components of Turbine Engine Flap After Modification of Casting Technology Parameters
Remišová A., Sládek A., Belan J.
Archives of Foundry Engineering
|
2018
|
Vol. 18, iss. 2
146--150
EN
First part of the article describes how we can by change of gating system achieve better homogeneity of product made by investment casting. Turbine engine flap was made by investment casting technology – lost wax casting. The casting process was realised in vacuum. The initial conditions (with critical occurrence of porosity) was simulated in ProCAST software. Numerical simulation can clarify during analysis of melt turbulent flow in gate system responsible for creation of entrained oxide films. After initial results and conclusions, the new gating system was created with subsequent turbulence analysis. The new design of gating system support direct flow of metal and a decrease of porosity values in observed areas was achieved. Samples taken from a casting produced with use of newly designed gating system was processed and prepared for metallography. The second part of article deals with identification of structural components in used alloy - Inconel 718. The Ni – base superalloys, which are combined unique physical and mechanical properties, are used in aircraft industry for production of aero engine most stressed parts, as are turbine blades.
3
Content available The effect of cooling rate on selected structural parameters of advanced cast Ni – base superalloys
Belan J., Vaško A., Kuchariková L., Švecová I.
Zeszyty Naukowe. Quality. Production. Improvement
|
2017
|
No. 1 (6)
20--30
EN
The Ni – base superalloys are used in aircraft industry for production of aero engine most stressed parts, as are turbine blades or turbine discs. The most stressing factor at Ni – base superalloys loading or working conditions are high temperature range of 700°C up to 850°C and, of course, centrifugal forces, and small vibrations, which produce bending of turbine blades inserted into turbine discs. All these factors cause various forms of microstructure degradation closely connected with decreasing of mechanical properties and shortening of working life as well. From this reason a dendrite arm spacing, carbides size and distribution, morphology, number and value of γ’ - phase are very important structural characteristics for blade lifetime prediction as well as aero engine its self. In this article are used methods of quantitative metallography for evaluation of structural characteristics mentioned above on experimental materials – Ni base superalloys ŽS6K and Inconel IN 738. The high temperature effect represented here by heat treatment at 800°C for 10 hours, and cooling rate, here represented by three various cooling mediums as water, air, and oil, on structural characteristics and application of quantitative methods evaluation with using of SEM are presented in this paper.
4
Content available Comparison of structure and mechanical properties of nodular cast irons after casting and after heat treatment
Vaško A., Belan J., Kuchariková L.
Zeszyty Naukowe. Quality. Production. Improvement
|
2017
|
No. 1 (6)
31--38
EN
The paper deals with the influence of charge composition on microstructure and mechanical properties of synthetic nodular cast irons after casting and after heat treatment (ferritizing annealing and isothermal heat treatment). Chemical composition of individual melts was regulated alternatively by carburizer and ferrosilicon (FeSi) or metallurgical silicon carbide (SiC). The results of experiments show that SiC additive positively influences the microstructure as well as mechanical properties of nodular cast iron, especially in specimens from the melts with higher ratio of steel scrap in the charge.
5
Content available Phase Transformations in Nickel base Superalloy Inconel 718 during Cyclic Loading at High Temperature
Jambor M., Bokuvka O., Novy F., Trsko L., Belan J.
Production Engineering Archives
|
2017
|
Vol. 15
15--18
EN
Nickel base superalloys are hi-tech materials intended for high temperature applications. This property owns a complex microstructure formed by matrix of Ni and variety of precipitates. The type, form and the amount of these phases significantly affect the resulting properties of these alloys. At sufficiently long exposure to high temperatures, the transformation phase can occur, which can lead to degradation of properties of these alloys. A cyclic plastic deformation can accelerate these changes, and they could occur at significantly lower temperatures or in shorter time of exposure. The aim of this study is to describe phase transformation, which can occur by a cyclic plastic deformation at high temperatures in nickel base superalloy Inconel 718.
6
Content available Comparison of low and high frequency fatigue tests
Vasko A., Belan J., Kucharikova L.
Production Engineering Archives
|
2017
|
Vol. 17
15--18
EN
The paper presents the results of low and high frequency fatigue tests carried out on nodular cast iron. The specimens of synthetic nodular cast irons from three different melts were studied in the high cycle fatigue region (from 105 to 108 cycles) using fatigue experimental equipments for low and high frequency cyclic loading. Low frequency fatigue tests were carried out at frequency f ≈ 120 Hz using the fatigue experimental machine Zwick/Roell Amsler 150HFP 5100; high frequency fatigue tests were carried out at frequency f ≈ 20 kHz using the ultrasonic fatigue testing device KAUP-ZU. Both fatigue tests were realised at sinusoidal cyclic push-pull loading (stress ratio R = –1) at ambient temperature (T = 20 ± 5 °C).
7
Content available A brief overview and metallography for commonly used materials in aero jet engine construction
Belan J., Vasko A., Kucharikova L.
Production Engineering Archives
|
2017
|
Vol. 17
9--14
EN
Aluminium, titanium, and nickel base alloys are mostly and widely used for aircraft jet engine construction. A proper evaluation of its microstructure is important from working safety point of view. To receive a well prepared sample of microstructure, some important steps have to be undertaken. Except for proper grinding and polishing of a sample, structure developing is a significant step, too. In order to develop microstructure various chemical reagents were used to achieve the best results for microstructure evaluation. The chemical reagents were used according to the previous knowledge and some new ones were also tested. Aluminium AK4-1č, titanium VT – 8, and nickel VŽL – 14 and ŽS6 – U alloys were used as an experimental materials. Alloy AK4-1č is used for fan blade production with working temperatures up to 300°C. It is a forged piece of metal machined down into final shape by five-axe milling machine. Alloy VT – 8 is used for high pressure compressor rotor blade production with working temperatures up to 500°C. Blades are forged as well and finally grinded. Finally nickel base alloys VŽL – 14 and ŽS6 – U are used for turbine blade production with working temperatures up 950°C. Blades for turbine are casted into mould with reducible models.
8
Content available Study of the precipitation hardening process in recycled Al-Si-Cu cast alloys
Kuchariková L., Tillová E., Matvija M., Belan J., Chalupová M.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 1
397--403
EN
The formation of extremely small uniformly dispersed particles of a second phase within the original phase matrix during heat treatment changed material properties. Therefore the characterization of precipitation had been investigated using high resolution transmission electron microscopy (TEM) and electron diffraction of thin foils for an AlSi9Cu3 cast alloy. For investigation the hardening effect onto mechanical properties of aluminium cast was used heat treatment, which consisted from solution treatment at 515°C / 4 hours (h), followed by quenching into water with temperature 50°C and artificial aging using different temperatures 170°C and 190°C with different holding time 2, 4, 8, 16, and 32 hours. The observations of microstructure and substructure reveals that precipitation hardening has caused great changes in size, morphology and distributions of structural components, the formation of precipitates of Cu phases, and the change of mechanical properties as well.
9
Content available Study of Bending Fatigue Properties of Al-Si Cast Alloy
Tillová E., Závodská D., Kuchariková L., Chalupová M., Belan J.
Archives of Metallurgy and Materials
|
2017
|
Vol. 62, iss. 3
1591--1596
EN
Fatigue properties of casting Al-alloys are very sensitive to the microstructural features of the alloy (e.g. size and morphology of the eutectic Si, secondary dendrite arm spacing – SDAS, intermetallics, grain size) and casting defects (porosity and oxides). Experimental study of bending fatigue properties of secondary cast alloys have shown that: fatigue tests up to 106-107cycles show mean fatigue limits of approx. 30-49 MPa (AlSi9Cu3 alloy – as cast state), approx. 65-76 MPa (AlSi9Cu3 alloy after solution treatment) and 60-70 MPa (self-hardened AlZn10Si8Mg alloy) in the tested casting condition; whenever large pore is present at or near the specimen’s surface, it will be the dominant cause of fatigue crack initiation; in the absence of large casting defects, the influence of microstructural features (Si morphology; Fe-rich phases) on the fatigue performance becomes more pronounced.
10
Content available Fractography analysis of Inconel 718 fatigued at 700°C
Jambor M., Belan J., Bokuvka O., Novy F.
Production Engineering Archives
|
2016
|
Vol. 13, No. 4
20--25
EN
This work deals with the fractography analysis of nickel-base superalloy Inconel 718 fatigued at 700°C in air atmosphere in the high cycle region. During cyclic loading of this alloy at high temperatures some different mechanisms compared to cyclic loading at ambient temperature take place. Cyclic plastic deformation at high temperatures causes some structural changes, which could have some influence.
11
Content available Employing various metallography methods at high temperature alloy fatigue tests evaluation
Belan J., Kucharikova L., Vasko A., Chalupova M., Svecova I.
Production Engineering Archives
|
2016
|
Vol. 13, No. 4
11--15
EN
Microstructures of superalloys have dramatically changed throughout the years, as modern technology of its casting or forging has become more sophisticated. The first superalloys have polyedric microstructure consisting of gamma solid solution, some fraction of gamma prime and of course grain boundaries. As demands on higher performance of aero jet engine increases, the changes in superalloys micro-structure become more significant. A further step in microstructure evolution was directionally solidified alloys with columnar gamma prime particles. The latest microstructures are mostly monocrystalline, oriented in [001] direction of FCC gamma matrix. All microstructure changes bring necessity of proper preparation and evaluation of microstructure. Except for the already mentioned structures have gamma double prime and various carbides form can be seen. These structural parameters have mainly positive influence on important mechanical properties of superalloys. The paper deals with a microstructural evaluation of both groups of alloys – cast and as well as wrought. Micro-structure evaluation helps to describe mechanism at various loading and failure of progressive superalloys. Such an example where micro-structure evaluation is employed is fractography of failure surfaces after fatigue tests, which are examples of metallography evaluation de-scribed in this paper as a secondary objective.
12
Content available Morphology of intermetallic phases in Al-Si cast alloys and their fracture behaviour
Hurtalova L., Tillova E., Chalupova M., Belan J.
Production Engineering Archives
|
2015
|
Vol. 6, No. 1
2--5
EN
Applications of Al-Si cast alloys in recent years have increased especially in the automotive industry (dynamic exposed cast, engine parts, cylinder heads, pistons and so on). Controlling the microstructure of secondary aluminium cast alloys is very important, because these alloys contain more additional elements that form various intermetallic phases in the structure. Therefore, the contribution is dealing with the valuation type of intermetallic phases and their identification with using optical and scanning microscopy. Some of the intermetallic phases could be identified on the basis of morphology but some of them must be identified according EDX analysis. The properties of aluminium alloy are affected by morphology of intermetallic phases and therefore it is necessary to study morphology and its fracture behaviour. The present work shows morphology and typical fracture behaviour as the most common intermetallic phases forming in Al-Si alloys.
13
Content available remote Applications of methods of quantitative metallography in materials engineering
Vasko A., Belan J.
International Journal of Applied Mechanics and Engineering
|
2010
|
Vol. 15, no 2
405-410
EN
The paper deals with the comparison of different methods of quantitative metallography, namely: the evaluation of the microstructure by etalons, measurement of structural parameters by coherent test grids and automatical image analysis. The advantages or disadvantages of individual methods are shown on the example of evaluation of the microstructure of graphitic cast irons, carbon steels, silumins and nickel superalloys.
14
Content available remote The degradation processes in high loaded casts
Ďuriníková E., Belan J., Tillová E.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 1 spec.
207--210
EN
In this work are described structural changes of jet engine DV–2 turbine blades and effect of degradation process. Turbine blades work in aggressively environs and because of that there are rate among high loaded cast stock. As an experimental material we have chose nickel superalloy ŽS6K with surface heat - resisting alitize layer. Evaluation is slant on largeness wearing over work of certain number of hour in operation. Effect working environs and overrun working temperatures is show changes measures as well as changes macrostructure of basic material blades. Evaluate is advance quantitative metallography through the medium metallographic software NIS element. Quantitative analysis evaluate thickness measures, quality control outer look and lack mixture in the seat, which is not splash, is precede by lack of near another applied protective layer. Allowance is knot on last examination in the area ratings protective heat-resisting layers and gives records for others possible ratings and experiments in this area.
15
Content available remote Identification of cast iron type with using of NDT methods
Belan J.
Archives of Foundry Engineering
|
2010
|
Vol. 10, iss. 1 spec.
103--106
EN
The aim of this paper is to demonstrate the capability of ultrasonic techniques in the assessment of the structure and properties of cast irons, and also contribute to the database concerning the use of ultrasonic velocity and attenuation measurements for quality control. In the experiments, cast iron specimens with different graphite shape (lamellar, vermicular and nodular shape) and different matrix composition were cast. Ultrasonic velocity measurements were carried out on the as-cast specimens with STARMANS DiO 562–2CH ultrasonic flaw detector. Then, the results of ultrasonic measurements were correlated with the microstructural investigations on the specimens.
16
Content available remote Influence of technological factors on eutectic silicon morphology in Al-Si alloys
Skočovsky P., Tillová E., Belan J.
Archives of Foundry Engineering
|
2009
|
Vol. 9, iss. 2
169-172
EN
From the background about Al-Si alloys modifying from eutectic silicon morphology and mechanical properties relation point of view is at solving of chosen technological problems used structural analysis and Si morphology quantification. There were solved two concrete problems: parameters of solution annealing AlSi9Cu3 alloy and confirming of laser treatment influence on AlSi7Mg0.3 alloy structure. In both cases have material heating caused spheroidization of eutectic silicon. Optimal regime of AlSi9Cu3 alloy (515 oC/4 hrs.) solution annealing was confirmed based on structural analysis, which have achieved fine globular silicon particles segregation and structural changes study at AlSi7Mg0,3 alloy after laser treatment showed improving of mechanical properties, proved also with metallography analysis. Modern methods of structure analysis application enable to spread present knowledge's in area of technological research.
17
Content available remote Influence of cooling rate on y' morphology in cast Ni - base superalloy
Belan J.
Archives of Foundry Engineering
|
2009
|
Vol. 9, iss. 2
101-104
EN
The Ni - base superalloys, which are combined an unique physical and mechanical properties, are used in aircraft industry for production of aero engine most stressed parts, as are turbine blades. From this reason a dendrite arm spacing, carbides size and distribution, morphology, number and value of [...] - phase are very important structural characteristics for blade life time prediction as well as aero engine its self. In this article are used methods of quantitative metallography (software LUCIA for carbides evaluation, measuring of secondary dendrite arm spacing and coherent testing grid for [...] - phase evaluation) for evaluation of structural characteristics mentioned above on experimental material - Ni base superalloy ŽS6K. The high temperature effect represented here by heat treatment at 800oC followed with holding time about 10 hours, and cooling rate, here represented by three various cooling mediums as water, air, and oil, on structural characteristics and application of quantitative methods evaluation are presented in this paper.
18
The quantitative metallography of ni - base superalloys
Belan J., Skočovský P.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
|
2005
|
z. 86
83-88
19
Content available remote Degradacja w wyniku eksploatacji warstwy aluminiowo-krzemowej łopatek turbinowych wykonywanych na bazie Ni
Skočovský P., Podrábský T., Belan J.
Archiwum Technologii Maszyn i Automatyzacji
|
2004
|
Vol. 24, nr 1
45-52
PL
W artykule przedstawiono badania struktury łopatek silnika samolotowego, które wyprodukowano z nadstopu niklu ŻS6K i w celu zwiększenia żaroodporności pokryto warstwą alumi-niowo-krzemową. Na podstawie analizy metalograficznej i mikroanalizy składu chemicznego poszczególnych warstw opisano zmiany zachodzące w warstwie aluminiowo-krzemowej podczas eksploatacji silnika samolotowego (do 2000 h).
EN
The paper deals with structure of jet engine DV-2 blades, which are made from Ni-base su-peralloy ŻS6K and for increasing of a high - resistant are covered by protective alitize layer. There have been described the changes that occurred in this alitize layer during working of jet engine (till 2000 h. of operation), based on metallographic analyses and micro analyses of single layer's chemical composition.
20
Content available remote Non-conventional methods for evaluating of Ni-base superalloys structure
Belan J., Skocovsky P., Podrabsky T.
Archiwum Odlewnictwa
|
2004
|
R. 4, nr 11/1
35--40
EN
The paper is presented a basic characteristic of developing non - conventional methods and example of its application at systematic analyse of influence on base structure aero engine turbine blade operation conditions made from Ni - base superalloy ŽS6K. The &gamma' and protective alitize layer were evaluated with using of color contrast and quantitative microfractography methods.
PL
Artykuł zajmuje się badaniami struktury łopatek silnika samolotowego, które wyprodukowano z nadstopu niklu ŽS6K i w celu powiększenia żaroodporności pokryto warstwą aluminiowo-krzemową. Opisano zmiany, przebiegające w warstwie aluminiowo-krzemowej podczas ruchu silnika samolotowego (do 2000 h) na podstawie przeprowadzonej analizy metalograficznej i mikroanalizy składu chemicznego poszczególnych warstw.
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