Browsing by Subject "grain refinement"

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Access status: Open Access ,
Effect of grain refinement on mechanical properties of microalloyed steels
(2006) Muszka, Krzysztof; Majta, Janusz; Bienias, Łukasz
The goal of the present work was to study the effect of grain size and strain rate on the mechanical properties of microalloyed steels. The range of the microstructures was developed and their mechanical properties were measured under quasi-static conditions. The influence of different thermomechanical parameters on grain refinement, and thus, on final mechanical behavior of these steels seems to be very important issue, because of their application as the materials with both high strength and ductility. There is a clear lack of understanding of the role of intermediate ultrafine microstructures on the mechanical response of structural steels, which is important as this is the refinement level most likely to be achieved under industrial processes. The main scope of this research includes the development of thermomechanical treatments to produce ultra fine-grained steels with enhanced properties. These materials will be developed for the application in many industries (e.g. automotive industry, shipbuilding), and in any commercial applications where very good properties and good-quality construction materials are of paramount importance. The results of this work will allow to systematically correlate the evolution of deformation microstructure and the deformation mechanisms operating in fine-grained materials during processing. This work will also be directed towards understanding the specific strengthening mechanisms by which the plastic deformation leads to a refined grain size.
Access status: Open Access ,
Grain-size prediction model in aluminum castings manufactured by Low-Pressure technology
(AGH University of Science and Technology Press, 2018) Fernández-Calvo, Ana Isabel; Lizarralde, Ibon; Sal, Elisa; Rodríguez, Patxi; Ochoa de Zabalegui Pereda, María Edurne; Cia, Igor; Rios, Ariane
The grain refinement in a real casting manufactured by Low Pressure Die Casting (LPDC) such as wheels and steering knuckles depends on the grain-refinement potential of the metal and the geometry of the part/process parameters. For this study, the effect of the cooling rate on the AlSi7Mg alloy with different metal qualities in terms of grain refinement was tested. The grain size has been metallographically evaluated in cylindrical test pieces and in the real wheels and steering knuckles manufactured at the Mapsa and Fagor Ederlan foundries. The Thermolan®-Al system has been used to evaluate the nucleation potential in terms of grain size on a standard cup. The grain size has been modeled taking into account the effect of the cooling rate measured in the center of the cylindrical test parts and the different grain-size potential. Different grades of refinement have been tested. The grain size measured in a real casting (wheel and steering knuckle) was used to calibrate the model for a real part in LPDC for different grain-size potential.