Browsing by Author "Galarraga, H."
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Item Development of new Al-Si9Cu3 alloys for HPDC components with tailored properties(World Foundry Organization, 2014) Vicario, I.; Anza, I.; Sáenz De Tejada, F.; García, J. C.; Galarraga, H.; Merchán, M.; PROMETAL; CIRMETALAluminium high pressure die casting (HPDC) is the most common process in order to produce aluminium castings, due to the excellent balance of cost and properties for high series production volumes. The AlSi9Cu3 is the most common used aluminium alloy, representing approximately the 70% of the HPDC produced parts. AlSi9Cu3 alloys Nevertheless, conventional AlSiCu3 alloys present certain limitations in terms of mechanical properties attainable due to the intrinsic porosity of HPDC castings as well as the alloy composition. New process variants and alloys have been developed in recent years trying to improve these aspects. AlSi9Cu3 standards have a wide range for alloying elements, that can vary for example in the AlSi9Cu3(Fe) EN-AC 46000 from 8-11% in the Silicon alloying element. For HPDC the standard properties are Elongation (E) < 1%, Yield strength (Y.E.) 140 MPa, Tensile Strength (T.S.) 240 Mpa and Hardness <80 HB. The present work approaches the development of new alloys similar to the AlSi9Cu3 alloys, but with tailored properties in function of the desired requirements. Specific ranges of compositions provide improvements in the elongation, yield strength, ultimate tensile strength and hardness and also combinations of them. As cast properties shows an alloy with E > 1%, Y.S. >200 MPa, T. S. >320 Mpa and Hardness >135 HB.Item Equipamiento y metodología para la determinación de la vida de materiales para moldes(2010) Abuin, A.; Galarraga, H.; Crespo, I.; Plaza, L. M.; Carnicer, P.; Vicario, I.; García, J. C.; SG; CIRMETAL; PROMETAL; Tecnalia Research & InnovationDies used in the non ferrous die casting process, have a limited service life due to the damage effect by surface cracking appearance. These cracks are mainly produced by thermal fatigue, which are promoted by a repeated heating and cooling process through working cycles. The existing demand to improve materials to extend the die's service life leads to the development of new equipments to test the material behaviour. INASMET-TECNALIA in collaboration with FEAF (Spanish Federation of the Foundry Associations), has developed a testing machine to evaluate the thermal fatigue behaviour of steels used to manufacture dies. This testing machine is able to test forty samples simultaneously, getting a remarkable advantage in regard to previous developed test equipment. The versatility of heating and cooling system makes possible to test all kind of materials in very different thermal fatigue conditions.Item Study of the influence of alloying elements on the high temperature properties of wrought aluminium alloys(World Foundry Organization, 2014) Merchán, M.; Egizabal, P.; Galarraga, H.; Alvarez, D.; CIRMETAL; Tecnalia Research & InnovationAluminium is nowadays one of the most important materials in the aeronautical sector. Its lightness and good specific mechanical resistance have favoured its increased use in an industry very concerned with weight reduction. New potential applications have been identified that require new alloys with improved performance in terms of mechanical strength and creep resistance. The present work deals with a design of experiment approach to identify wrought aluminium alloys with good mechanical properties at high temperatures (200-250°C). Age hardened wrought alloys are much used for aeronautic applications. Age hardening gives the alloy a higher strength due to the precipitation of second phases that act as an obstacle for the dislocation movement and pin the grain boundaries avoiding the grain growth. However, the coarsening of these precipitates at temperatures above 180°C leads to an important reduction in the mechanical properties of the alloy when they are exposed to high temperatures during long periods. Several heat resistant aluminium based materials that have been developed in the last years do exist that might already be used at temperatures over 200°C. However, most of them are either based on the incorporation of expensive alloying elements such as rare earths, silver or scandium or on the addition of reinforcements (SiC, Al2O3, B4C, etc.). Other alloys produced by mechanical alloying, rapid solidification or spray forming may also work at those working conditions. Notwithstanding, these solutions cannot be widely used as they are either too expensive or present technical drawbacks such as insufficient ductility, low machinability or recycling problems. The present work aims at developing such alloys through a methodology based on the identification of the effect of 12 different alloying elements and their combinations in the properties of aluminium alloys and the selection of the optimum combination of these alloying elements through the Taguchi methodology. The steps followed for the selection of the alloying elements and the maximum and minimum ranges are explained and the process of the production and selection of the alloys is explained. The different alloys were cast and extruded in order to obtain tensile specimens that were tested at 250°C. Eventually the analysis of the microstructure of the most promising alloys is presented.