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1
Content available Contribution to the Identification of Porosity Type in AlSiCu High-Pressure-Die-Castings by Experimental and Virtual Way
100%
Ignaszak Z. , Hajkowski J.
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tom Vol. 15, iss. 1
143--151
EN
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.
2
Content available Experimental and Simulation Tests on the Impact of the Conditions of Casting Solidification from AlSi9Cu3 Alloy on their Structure and Mechanical Properties
100%
Hajkowski J. , Ignaszak Z.
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tom Vol. 18, iss. 1
167--175
EN
The impact of casting conditions on microstructure a and mechanical properties was described, especially for cast products from AlSi9Cu3 alloy. Particular attention was paid to the parameters of dendritic structure: DAS 1 and DAS 2. Selected mechanical properties (by static tension test) of test castings made using basic technologies of casting: GSC - gravity sand casting, GDC - gravity die-casting and HPDC - high-pressure die-casting, are presented for cast-on test bars and cast separately. Casts were made of the same alloy AlSi9Cu3. Fractures and the zone near the fracture (after static tension test) was subjected to VT - visual tests, PT - penetration tests and metallographic tests. The condition of porosity (fracture zone) was also assessed. The analysis of virtual results was performed using the NovaFlow & Solid system together with the database and they were compared to experimental tests. This way of validation was applied in order to assess the correlation between the local rate of cooling and the size of DAS for GSC, GDC and HPDC technologies. Finally, the correlation between the parameters of structure and mechanical properties with regard to the impact of porosity was signalized.
3
Content available Contribution to the Identification of Porosity Type in AlSiCu High-Pressure-Die-Castings by Experimental and Virtual Way
100%
Ignaszak Z. , Hajkowski J.
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nr 1
4
Content available remote Prediction of useful casting structure applying Cellular Automaton method
80%
Ignaszak Z. , Hajkowski J. , Hajkowski M.
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2009
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tom Vol. 9, iss. 3
61-66
EN
The results of simulation investigations of primary casting's structure made of hypoeutectic Al-Si alloy using the Calcosoft system with CAFE 3D (Cellular Automaton Finite Element) module are presented. CAFE 3-D module let to predict the structure formation of complete castings indicating the spatial distribution of columnar and equiaxed grains. That simplified model concerns only hypoeutectic phase. Simulation investigations of structure concern the useful casting of camshaft which solidified in high-insulation mould with properly chills distribution. These conditions let to apply the expedient locally different simplified the grains blocs geometry which are called by the authors as pseudo-crystals. The mechanical properties in selected cross-sections of casing are estimated.
5
Content available remote Struktura i porowatość odlewów ze stopu aluminium a właściwości mechaniczne
80%
Bernat Ł. , Hajkowski J. , Hajkowski M.
Archiwum Odlewnictwa
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2006
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tom R. 6, nr 22
41-48
PL
W artykule przedstawiono wyniki badań krzywych stygnięcia, kryterium Niyamy, udział porowatości, parametry struktury (odległość między gałęziami w dendrytach i średni kąt nachylenia dendrytów) i właściwości mechanicznych (R_{0,2}, R_{m} i wytrzymałość zmęczeniowa) odlewu płyty ze stopu EN AC-AlSi7Mg krzepnącego w różnych warunkach cieplnych. Określono wpływ kryterium Niyamy na porowatość odlewu oraz wpływ udziału porowatości na właściwości mechaniczne przy niestałych wartościach odległości między gałęziami w dendrytach i średniego kąta nachylenia dendrytów.
EN
In the paper the results of investigations of cooling curves, Niyama criterion, participation of porosity, microstructure parameters (the space between arms in dendrites and mean inclination angle of dendrites) and mechanical properties (R_{0,2}, R_{m} and fatigue strength) of plate casting made of EN AC-A1Si7Mg alloy solidify in different thermal conditions was presented. The influence of Niyama criterion on porosity and participation of porosity on mechanical properties with unstable parameters of spacing between arms in dendńtes and mean inclination angle of dendrites was determined.
6
Content available remote Sensitivity testing practice on pre-processing parameters in hard and soft coupled modeling
80%
Ignaszak Z. , Hajkowski J. , Hajkowski M.
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tom Vol. 10, iss. 1
51-58
EN
This paper pays attention to the problem of practical applicability of coupled modeling with the use of hard and soft models types and necessity of adapted to that models data base possession. The data base tests results for cylindrical 30 mm diameter casting made of AlSi7Mg alloy were presented. In simulation tests that were applied the Calcosoft system with CAFE (Cellular Automaton Finite Element) module. This module which belongs to "multiphysics" models enables structure prediction of complete casting with division of columnar and equiaxed crystals zones of [alpha]phase. Sensitivity tests of coupled model on the particular values parameters changing were made. On these basis it was determined the relations of CET (columnar-to-equaiaxed transition) zone position influence. The example of virtual structure validation based on real structure with CET zone location and grain size was shown.
7
Content available Mechanical properties of Al-Si-Mg alloy castings as a function of structure refinement and porosity fraction
80%
Hajkowski M. , Bernat Ł. , Hajkowski J.
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tom Vol. 12, iss. 4
57-64
EN
During design of the casting products technology, an important issue is a possibility of prediction of mechanical properties resulting from the course of the casting solidification process. Frequently there is a need for relations describing mechanical properties of silumin alloys as a function of phase refinement in a structure and a porosity fraction, and relations describing phase refinement in the structure and the porosity fraction as a function of solidification conditions. The study was conducted on castings of a 22 mm thick plate, made of EN AC-AlSi7Mg0,3 alloy in moulds: of quartz sand, of quartz sand with chill and in permanent moulds. On the basis of cooling curves, values of cooling rate in various casting parts were calculated. The paper also presents results of examination of distance between arms in dendrites of a solid solution \alfa (DASL), precipitations length of silicon in an eutectic (DlSi) and gas-shrinkage porosity (Por) as a function of cooling rate. Statistical relations of DASL, DlSi, Por as a function of cooling rate and statistical multiparameter dependencies describing mechanical properties (tensile strength, yield strength, elongation) of alloy as a function of DASL, DlSi and Por are also presented in the paper.
8
Content available Methodology of Comparative Validation of Selected Foundry Simulation Codes
80%
Ignaszak Z. , Popielarski P. , Hajkowski J. , Codina E.
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tom Vol. 15, iss. 4
37--44
EN
The validation of each simulation code used in foundry domain requires individual approach due to its specificity. This validation can by elaborated on the basis of experimental results or in particular cases by comparison the simulation results from different codes. The article concerns the influence of grey cast iron density curve and different forms of solid fraction curve Fs=f(T) on the formation of shrinkage discontinuities. Solid fraction curves applying Newtonian Thermal Analysis (NTA) were estimated. The experimental and numerical simulation tests were performed on the castings, which were made with Derivative Thermal Analysis (DerTA) standard cups. The numerical tests were realized using NovaFlow&Solid (NF&S), ProCast and Vulcan codes. In this work, the coupled influence of both curves on the dynamics of the shrinkage-expansion phenomena and on shrinkage defects prognosis in grey cast iron castings has been revealed. The final evaluation of the simulation systems usefulness should be based on validation experiment, preceded by comparing the simulation results of available systems which are proposed in given technology.
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