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Kraków, Poland

Lelito J.,AGH University of Science and Technology | Zak P.,AGH University of Science and Technology | Suchy J.S.,AGH University of Science and Technology | Krajewski W.,AGH University of Science and Technology | And 2 more authors.
China Foundry | Year: 2011

The grain density, Nv, in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling, ΔT, of a liquid alloy. This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy. The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling. This model in connection with model of crystallisation, which is based on chemical elements diffusion and grain interface kinetics, can be used to predict casting quality and its microstructure. Nucleation models have parameters, which exact values are usually not known and sometimes even their physical meaning is under discussion. Those parameters can be obtained after mathematical analysis of the experimental data. The composites with 0, 1, 2, 3 and 4wt.% of SiC particles were prepared. The AZ91 alloy was a matrix of the composite reinforcement SiC particles. This composite was cast to prepare four different thickness plates. They were taken from the region near to the thermocouple, to analyze the undercooling for different composites and thickness plates and its influence on the grain size. The microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles, and undercooling with grain size. These values were used to approximate nucleation model adjustment parameters. Obtained model can be very useful in modelling composites microstructure.


Lelito J.,AGH University of Science and Technology | Zak P.,AGH University of Science and Technology | Suchy J.S.,AGH University of Science and Technology | Krajewsk W.,AGH University of Science and Technology | And 2 more authors.
69th World Foundry Congress 2010, WFC 2010 | Year: 2010

Magnesium alloys and their composites have been attracting attention as an important lightweight material and are being utilized in the automobile and aerospace industries. In terms of the reinforcement in magnesium - based composites, the SiC particles are extensively used because magnesium cannot form any stable carbide. The grain density in the solid state Nv after solidification of AZ911SiC composite is a function of maximum undercooling of a liquid alloy ΔT. This type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the alloy. The aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and undercooling. This model in connection with model of crystallisation, which is based on chemical elements diffusion and grain interface kinetics, can be used to predict casting quality and its microstructure. Nucleation models have parameters, which exact values are usually not known and sometimes even their physical meaning is under discussion. Those parameters can be obtained after mathematical analyze of the experimental data. The composite with 0,1,2,3 and 4 wt. % of SiC particles were prepared. The AZ91 alloy was a matrix of the composite reinforcement SiC particles. This composite was casted to prepare four different thickness plates. They were taken from the region near to the thermocouple, to analyze the undercooling for different composites and thickness plates and its influence on the grain size. The microstructure and thermo analyze gave set of values that connect mass fraction of SiC particles,and undercooling with grain size. These values were used to approximate nucleation model adjustment parameters. Obtained model can be very useful in modelling composites microstructure.


Jakumeit J.,ACCESS e.V. | Jana S.,ACCESS e.V. | Bottger B.,ACCESS e.V. | Laqua R.,ACCESS e.V. | And 2 more authors.
IOP Conference Series: Materials Science and Engineering | Year: 2011

Micro-shrinkage porosity in aluminum casting is analysed by computer simulation using three criteria functions and a fully-coupled shrinkage porosity model. Three process simulations of different precision were executed as basis for the porosity prediction for investigation of the impact of simulation precision on porosity prediction. To validate the simulation predictions, three identical blocks were cast in a special experimental setup. Chill plates enforce shrinkage porosity, which was analyzed using computer tomography. The results demonstrate that both precise numerical simulations and precise porosity models are needed for reliable porosity prediction.


Siegbert R.,Chair for Computational Analysis of Technical Systems | Yesildag N.,Institute of Plastics Processing IKV | Frings M.,Chair for Computational Analysis of Technical Systems | Schmidt F.,Foundry Institute | And 8 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2015

Individualized production, which is a major goal of many high-wage countries, describes a production process in which all elements of a production system are designed in such a way that they enable a high level of product variety at mass production costs. This paper demonstrates recent advances in the individualized production with die-based manufacturing processes, namely high-pressure die casting and plastics profile extrusion. Within these application areas, the chosen approach aiming at individualized production is based on the use of numerical die and process design. The design procedure relies on numerical process simulations based on a nonlinear optimization library and a spline-based geometry kernel. All components interact automatically without requiring user interaction; thus, a completely independent optimization cycle can be achieved. The numerical optimization helps to reduce—or even eliminate—the so far very characteristic manual reworking steps of an original die or process design. These reworking steps are a major cost factor when it comes to individual production. Their abolishment through the presented numerical approaches therefore represents a large step towards the concept of individualized production. © 2015 Springer-Verlag London

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