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    Wyświetlanie 1-11 z 11
    Tytuł:
    Influence of Defects on Deformation Behavior of High-Pressure Die-Casting Magnesium Alloys
    Autorzy:
    Braszczyńska-Malik, Katarzyna
    Powiązania:
    https://bibliotekanauki.pl/articles/27314146.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    magnesium alloy
    high-pressure die casting
    gas porosity
    shrinkage porosity
    microstructure
    deformations
    stop magnezu
    odlewanie wysokociśnieniowe
    porowatość gazowa
    porowatość skurczowa
    mikrostruktura
    deformacje
    Opis:
    The results of investigations of defects in AME-series magnesium alloys produced by the high-pressure die-casting method are presented. The analyzed magnesium alloys contain about 5 wt% aluminum and 1-5 wt% rare earth elements introduced in the form of mischmetal. The casts were fabricated using a regular type cold-chamber high-pressure die-casting machine with a 3.2 MN locking force. The same surfaces of the casts were analyzed before and after the three-point bending test in order to determine the influence of the gas and shrinkage porosity on the deformation behavior of the alloys. The obtained results revealed that the most dangerous for the cast elements is the shrinkage porosity, especially stretched in the direction perpendicular to the that of the tensile stress action. Additionally, the influence (Mg) solid solution and its interaction on the cracking process was described [alpha] of deformation twins arise in the dendrites of the primary.
    Źródło:
    Archives of Foundry Engineering; 2023, 23, 2; 10--14
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Validation Tests of Prediction Modules of Shrinkage Defects in Cast Iron Sample
    Autorzy:
    Hajkowski, J.
    Roquet, P.
    Khamashta, M.
    Codina, E.
    Ignaszak, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/380838.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    castings defects
    shrinkage
    porosity
    ductile cast iron
    validation
    wady odlewów
    porowatość
    żeliwo sferoidalne
    Opis:
    The paper presents the results of experimental-simulation tests of expansion-shrinkage phenomena occurring in cast iron castings. The tests were based on the standard test for inspecting the tendency of steel-carbon alloys to create compacted discontinuities of the pipe shrinkage type. The cast alloy was a high-silicone ductile iron of GJS - 600 - 10 grade. The validation regarding correctness of prognoses of the shrinkage defects was applied mostly to the simulation code (system) NovaFlow & Solid CV (NFS CV). The obtained results were referred to the results obtained using the Procast system (macro- and micromodel). The analysis of sensitivity of the modules responsible for predicting the shrinkage discontinuities on selected pre-processing parameters was performed, focusing mostly on critical fractions concerning the feeding flows (mass and capillary) and variation of initial temperature of the alloy in the mould and heat transfer coefficient (HTC) on the casting - chill interface.
    Źródło:
    Archives of Foundry Engineering; 2017, 17, 1; 57-66
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Contribution to the Identification of Porosity Type in AlSiCu High-Pressure-Die-Castings by Experimental and Virtual Way
    Autorzy:
    Ignaszak, Z.
    Hajkowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/379466.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Al-Si alloy
    gravity
    high pressure
    die casting
    microstructure
    gas porosity
    shrinkage porosity
    virtualization process
    complementary model validation
    stop Al-Si
    odlewanie ciśnieniowe
    porowatość gazowa
    wirtualizacja
    walidacja modelu
    Opis:
    The paper concerns the problem of discontinuity in high pressure die castings (HPDC). The compactness of their structure is not perfect, as it is sometimes believed. The discontinuities present in these castings are the porosity as follow: shrinkage and gas (hydrogen and gas-air occlusions) origin. The mixed gas and shrinkage nature of porosity makes it difficult to identify and indicate the dominant source. The selected parameters of metallurgical quality of AlSi9Cu3 alloy before and after refining and the gravity castings samples (as DI - density index method), were tested and evaluated. This alloy was served to cast the test casting by HPDC method. The penetrating testing (PT) and metallographic study of both kinds of castings were realized. The application of the NF&S simulation system allowed virtually to indicate the porosity zones at risk of a particular type in gravity and high-pressure-die-castings. The comparing of these results with the experiment allowed to conclude about NF&S models validation. The validity of hypotheses concerning the mechanisms of formation and development of porosity in HPDC casting were also analyzed.
    Źródło:
    Archives of Foundry Engineering; 2015, 15, 1; 143-151
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The role of metallurgical defects and microstructure on failure formation in roll necks of cast iron rolls
    Rola wad metalurgicznych oraz mikrostruktury w powstawaniu uszkodzeń czopów żeliwnych walców hutniczych
    Autorzy:
    Krawczyk, J.
    Pacyna, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/264314.pdf
    Data publikacji:
    2007
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    żeliwo
    walce hutnicze
    rzadzizna
    ledeburyt
    cementyt drugorzędowy
    grafit
    cast iron
    mill rolls
    shrinkage porosity
    ledeburite
    secondary cementite
    graphite
    Opis:
    This work presents the examples of structural reasons for failure of the necks of cast iron rolls. The most common reason for damage of metallurgical roll necks is a presence of shrinkage porosity in their volume. Moreover, a high fraction of ledeburitic cementite can lead to the formation of a continuous net of eutectic carbides, which facilitate cracking. Even very thin net of secondary carbides, formed on the boundaries of former grain of austenite, can significantly facilitate propagation of the crack. Continuous net of ledeburitic cementite, in the case of its precipitation in a form of bands and existence of hardened areas in the alloy matrix can lead to roll neck fracture relatively easy. The use of flake graphite cast iron for metallurgical rolls increases a risk of the fracture of roll neck.
    W niniejszej pracy przedstawiono przykłady strukturalnych przyczyn uszkodzeń czopów w żeliwnych walcach hutniczych. Najczęstszą przyczyną uszkodzeń czopów walców hutniczych jest zaleganie w nich obszarów rzadzizn. Ponadto duży udział cementytu ledeburytycznego może prowadzić do powstania ciągłej siatki węglików eutektycznych, która tworzy drogę łatwego pękania. Nawet bardzo cienka siatka węglików drugorzędowych utworzona na granicach pierwotnego ziarna austenitu może w znaczący sposób ułatwiać rozwój pęknięcia. Ciągła siatka cementytu ledeburytycznego, w przypadku jego wydzielania w postaci pasmowej oraz występowanie w osnowie obszarów podhartowanych, może doprowadzić do łatwego złamania czopa walca. Zastosowanie na walce hutnicze żeliwa z grafitem płatkowym zwiększa niebezpieczeństwo złamania czopa.
    Źródło:
    Metallurgy and Foundry Engineering; 2007, 33, 2; 89-96
    1230-2325
    2300-8377
    Pojawia się w:
    Metallurgy and Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of micro synthetic fibers confinement on properties of lightweight foamed concrete
    Autorzy:
    Mydin, Md Azree Othuman
    Powiązania:
    https://bibliotekanauki.pl/articles/2174053.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    pianobeton
    kurczenie się
    porowatość
    absorpcja wody
    wytrzymałość na ściskanie
    wytrzymałość na zginanie
    mikrowłókno syntetyczne
    foamed concrete
    shrinkage
    porosity
    water absorption
    compressive strength
    flexural strength
    micro synthetic fiber
    Opis:
    In this investigation, the confinement effects of micro synthetic fibers on lightweight foamed concrete (LFC) were examined. The parameters evaluated were porosity, water absorption, shrinkage, compressive strength, flexural strength and tensile strength. Three densities were cast which were 600 kg/m3, 1100 kg/m3, and 1600 kg/m3. Besides, the number of layers (1 to 3 layers) of micro synthetic fibers was also being examined. Based on the result obtained, the porosity improved by 8.0% to 16.3%, 13.8% to 25.6%, and 9.3% to 24.5% for the LFC with densities of 600 kg/m3, 1100 kg/m3, and 1600 kg/m3 confined with 1 layer, 2 layers, and 3 layers of micro synthetic fibers, respectively. Besides, for the water absorption test, the enhancements were 6.9% to 15.6%, 20.0 to 27.1%, and 12.2 to 29.6% for the respective densities and number of layers of micro synthetic fibers employed, while the drying shrinkage improved by 48.5% to 76.8%, 57.4% to 72.1%, and 43.2 % to 68.2% for the respective densities and number of layers of micro synthetic fibers employed. For the strength properties, a confinement with 3 layers of micro synthetic fibers showed significant results, where enhancements of 153% (600 kg/m3), 97% (1100 kg/m3), and 102% (1600 kg/m3) were obtained for the compression strength; 372% (600 kg/m3), 258% (1100 kg/m3), and 332% (1600 kg/m3) for the bending strength; and 507% (600 kg/m3), 343% (1100 kg/m3), and 332% (1600 kg/m3) for the splitting tensile strength, respectively, compared to the control LFC.
    Źródło:
    Archives of Civil Engineering; 2022, 68, 3; 411--428
    1230-2945
    Pojawia się w:
    Archives of Civil Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigating the Effect of Sisal Fibre Content on Durability Properties of Lightweight Foamed Concrete
    Autorzy:
    Mydin, Md Azree Othuman
    Powiązania:
    https://bibliotekanauki.pl/articles/2172354.pdf
    Data publikacji:
    2022
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    porosity
    lightweight foamed concrete
    sisal fibre
    shrinkage
    water absorption
    Opis:
    Lightweight foamed concrete is greatly permeable, and its durability performance reduce with rising in the number of voids. In turn to improve its durability properties, the solid matrix of lightweight foamed concrete can be adjusted by incorporating several plant-based fibres. The effect of sisal fibre in lightweight foamed concrete was not explored before in the current body of knowledge. Therefore, there is some uncertainty considering the mechanism by which and the extent to which the sisal fibre may impact lightweight foamed concrete durability properties. Thus, this laboratory study concentrates on distinguishing the potential employment of sisal fibre into lightweight foamed concrete. This investigation aims to establish the durability performance of lightweight foamed concrete with the presence of sisal fibre. Densities of 800 and 1600 kg/m3 were made and assesed. Different weight fractions of sisal fibre of 0.2%, 0.4%,0.6% and 0.8% were utilized. There were four durability perfomance of lightweight foamed concrete were evaluated such as shrinkage, ultrasonic pulse velocity (UPV), porosity and water absorption capacity. The experimental results had indicated that the addition of 0.6% of sisal fibre gave the optimum results for the durability properties. At 0.6% weight fraction of sisal fibre, the fibres reached maximum compaction in the cement matrix, which stemmed in exceptional mix regularity. Further than 0.6% inclusion of sisal fibre, accumulation and non-regularity scattering of fibres was detected, which led to reduction in entire parameters assessed.
    Źródło:
    Advances in Science and Technology. Research Journal; 2022, 16, 2; 141--149
    2299-8624
    Pojawia się w:
    Advances in Science and Technology. Research Journal
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Effect of Shell Thickness, Insulation and Casting Temperature on Defects Formation During Investment Casting of Ni-base Turbine Blades
    Autorzy:
    Raza, M.
    Irwin, M.
    Fagerström, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/382425.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    investment casting
    casting defect
    shrinkage porosity
    grain structure
    turbine blade
    Niyama criterion
    odlewanie precyzyjne
    wada odlewu
    struktura ziarnista
    łopatka turbinowa
    kryterium Niyamy
    Opis:
    Turbine blades have complex geometries with free form surface. Blades have different thickness at the trailing and leading edges as well as sharp bends at the chord-tip shroud junction and sharp fins at the tip shroud. In investment casting of blades, shrinkage at the tip-shroud and cord junction is a common casting problem. Because of high temperature applications, grain structure is also critical in these castings in order to avoid creep. The aim of this work is to evaluate the effect of different process parameters, such as, shell thickness, insulation and casting temperature on shrinkage porosity and grain size. The test geometry used in this study was a thin-walled air-foil structure which is representative of a typical hot-gas-path rotating turbine component. It was observed that, in thin sections, increased shell thickness helps to increase the feeding distance and thus avoid interdendritic shrinkage. It was also observed that grain size is not significantly affected by shell thickness in thin sections. Slower cooling rate due to the added insulation and steeper thermal gradient at metal mold interface induced by the thicker shell not only helps to avoid shrinkage porosity but also increases fill-ability in thinner sections.
    Źródło:
    Archives of Foundry Engineering; 2015, 15, 4; 115-123
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Controlled Precipitation Gaseous Cavities in Aluminium Castings
    Autorzy:
    Roučka, J.
    Hotař, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/380038.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    aluminium alloy
    porosity
    shrinkage
    gassing in melt
    pore morphology
    stop aluminium
    porowatość gazowa
    skurcz
    Opis:
    At thermal junctions of aluminium alloy castings and at points where risering proves to be difficult there appear internal or external shrinkages, which are both functionally and aesthetically inadmissible. Applying the Probat Fluss Mikro 100 agent, which is based on nano-oxides of aluminium, results in the appearance of a large amount of fine microscopic pores, which compensate for the shrinking of metal. Experimental tests with gravity die casting of AlSi8Cu3 and AlSi10Mg alloys have confirmed that the effect of the agent can be of advantage in foundry practice, leading to the production of castings without local concentrations of defects and without the appearance of shrinkages and macroscopic gas pores. Also, beneficial effect on the mechanical properties of the metal has been observed.
    Źródło:
    Archives of Foundry Engineering; 2015, 15, 4; 124-128
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Al-Si and Al-Si-Mg Cast Alloys Shrinkage Porosity Estimation
    Autorzy:
    Samavedam, S.
    Sundarrajan, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/382288.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    shrinkage characteristic
    porosity
    cast aluminium alloy
    rectangular shape
    process simulation
    stop aluminium
    porowatość
    kształt
    symulacja procesu
    Opis:
    US A356 and US 413 cast aluminium alloys shrinkage characteristic have been discussed in the present study. Specific volume reduction leads to shrinkage in castings and it can be envisaged as a casting defect. Finite difference based casting process simulation software has been used to study the shrinkage characteristic and it is quantified using mathematical formulae. The three dimensional model of the shrinkage defect has been constructed using CAD application software. Shrinkage characteristic has also been quantified through experimental validation studies and compared well with casting process simulation. Shrinkage characteristic study and control is essential for producing defect free castings. Influence of casting shape on the shrinkage characteristic has been studied in this paper.
    Źródło:
    Archives of Foundry Engineering; 2016, 16, 1; 61-68
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Prediction of Shrinkage Porosity in Femoral Stem of Titanium Investment Casting
    Autorzy:
    Sutiyoko, S.
    Suyitno, S.
    Mahardika, M.
    Syamsudin, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/947452.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    femoral stem
    shrinkage porosity
    commercially pure titanium
    investment casting
    rzadzizna odlewu
    tytan czysty
    odlewanie precyzyjne
    Opis:
    Design of gating system is an important factor in obtaining defect-free casting. One of the casting defects is a porosity caused by internal shrinkage in solidification process. Prediction of the internal shrinkage porosity in the femoral stem of commercially pure titanium (CP-Ti) is investigated based on the gating system design. The objective of this research is to get the best gating system between three gating system designs. Three gating system designs of the femoral stem were simulated in an investment casting method. The internal shrinkage porosity occurs on the largest part and near the ingate of the femoral stem. The gating system design that has ingates cross section area: 78.5; 157; and 128.5 mm2 has the least of the internal shrinkage porosity. This design has the most uniform solidification in the entire of the femoral stem. An experiment is conducted to validate the simulation data. The results of internal shrinkage porosity in the three gating system designs in the simulation were compared with the experiment. Based on the comparison, the trend of internal shrinkage porosity at the three gating system designs in the simulation agrees with the experiment. The results of this study will aid in the elimination of casting defect.
    Źródło:
    Archives of Foundry Engineering; 2016, 16, 4; 157-162
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shrinkage Porosity Criterion and Its Application to A 5.5 Ton Steel Ingot
    Autorzy:
    Zhang, C.
    Bao, Y.
    Wang, M.
    Zhang, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/382021.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    foundry industry
    quality management
    shrinkage porosity
    ingot solidification
    application of information technology
    numerical simulation
    przemysł odlewniczy
    zarządzanie jakością
    porowatość
    krzepnięcie
    zastosowanie technologii informatycznych
    symulacja numeryczna
    Opis:
    In order to predict the distribution of shrinkage porosity in steel ingot efficiently and accurately, a criterion R√L and a method to obtain its threshold value were proposed. The criterion R√L was derived based on the solidification characteristics of steel ingot and pressure gradient in the mushy zone, in which the physical properties, the thermal parameters, the structure of the mushy zone and the secondary dendrite arm spacing were all taken into consideration. The threshold value of the criterion R√L was obtained with combination of numerical simulation of ingot solidification and total solidification shrinkage rate. Prediction of the shrinkage porosity in a 5.5 ton ingot of 2Cr13 steel with criterion R√L>0.21 m･℃1/2･s-3/2 agreed well with the results of experimental sectioning. Based on this criterion, optimization of the ingot was carried out by decreasing the height-to-diameter ratio and increasing the taper, which successfully eliminated the centreline porosity and further proved the applicability of this criterion.
    Źródło:
    Archives of Foundry Engineering; 2016, 16, 2; 27-32
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-11 z 11

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