Browsing by Author "Lakehal, M."
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Item Development of aluminium alloys for the thixoforming process(2004) Azpilgain, Z.; Hurtado, I.; Basterrechea, G.; Gandarias, E.; Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Landa, I.; Wielanek, L.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe aluminium alloys A356 and A357 remain, up to the present, the most used alloys for the semisolid processing of components. Nevertheless, several authors have pointed out the gain in properties or economics that other alloy families could provide. In the present work two complementary alloy families are considered. From an economical point of view, modifications necessary to increase the properties of second fusion alloys are carried out. From the point of view of the potential of their properties, wrought alloys are modified and tested. A New Rheocasting pilot unit is used for obtaining the alloys with thixotropic characteristics. Previous work on the identification of the microstructural variables which determine the properties of the components allow to reduce those variables to the variation of the solid-liquid fraction as a function of the temperature, the particle size distribution, the particle aspect ratio and the esqueletonization. The composition variations in both alloy families are thus considered under the point of view of the control and optimisation of those parameters. In addition to the metallographic studies, thermodynamic calculations and calorimetry experiments have been performed to determine the optimum process window of the new alloys. A "direct squeeze casting method" with a preheated die has been used to obtain samples for the determination of mechanical properties.Item Magnetic molding foundry process of non ferrous and ferrous alloys(2005) Geffroy, P. M.; Goni, J.; Lakehal, M.; Beaugnon, E.; Silvain, J. F.; Centros PRE-FUSION TECNALIA - (FORMER)Magnetic molding technology, is a good alternative process in order to improve the metallurgical quality and dimensional tolerances of the final components that are presently produced through Lost Foam process. The first development of the magnetic molding process was performed at the same time of the lost foam process more than thirty years ago but it has never reached the same industrial development. The purpose of this study is to introduce the magnetic molding process, and to define the advantages and the characteristics of this process. Particular attention is given to the comparative results obtained with the lost foam and the magnetic molding processes with aluminum and grey cast iron. Eventually, the main factors involved in the magnetic molding process are discussed.Item Mise en forme des alliages d'aluminium à l'état semi-solide: Une technologie compétitive pour les pièces automobiles(2004-11) Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Akizu, A.; Landa, I.; Wielanek, L.; Azpilgain, Z.; Hurtado, I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe achievement of lighter automotive components is an important driving force m the development and optimization of casting techniques. Among these, Thixocasting and Squeeze Casting of aluminium alloys are presently used in the production of security components. In the present work, several production routes and aluminium alloys are considered. A die has been designed to produce a standard security component an automotive brake caliper. Simulation studies have been carried out to detect possible filling or solidification problems during casting and to solve them beforehand. Afterwards, automotive components have been produced with both a commercial globular structured A357 alloy through a semi-solid technology (Thixocasting) and a conventional A357 alloy by Squeeze Casting. General considerations of both casting processes are presented and some specific problems encountered are outlined. For comparison purposes, the automotive component selected has been also manufactured by means of other conventional casting technologies: sand casting, gravity die casting and low pressure die casting. Components from both sets of experiments have been heat treated and metallographic samples from problematic areas of the component selected have been thoroughly analyzed. Mechanical properties have been measured from tensile samples and the results compared for the different casting techniques evaluated.Item Processing of aluminium alloys in semi-solid state: A competitive technology for automotive components(2004) Goñi, J.; Eguizabal, P.; Lakehal, M.; Sarriés, I.; Akizu, A.; Landa, I.; Wielanek, L.; Azpilgain, Z.; Hurtado, I.; Centros PRE-FUSION TECNALIA - (FORMER); Tecnalia Research & InnovationThe achievement of lighter automotive components is an important driving force in the development and optimization of casting techniques. Among these, Thixocasting and Squeeze Casting of aluminium alloys are presently used in the production of security components. In the present work, several production routes and aluminium alloys are considered. A die has been designed to produce a standard security component: an automotive brake caliper. Simulation studies have been carried out to detect possible filling or solidification problems during casting and to solve them beforehand. Afterwards, automotive components have been produced with both a commercial globular structured A357 alloy through a semi-solid technology (Thixocasting) and a conventional A357 alloy by Squeeze Casting. General considerations of both casting processes are presented and some specific problems encountered are outlined. For comparison purposes, the automotive component selected has been also manufactured by means of other conventional casting technologies: sand casting, gravity die casting and low pressure die casting. Components from both sets of experiments have been heat treated and metallographic samples from problematic areas of the component selected have been thoroughly analyzed. Mechanical properties have been measured from tensile samples and the results compared for the different casting techniques evaluated.