Browsing by Author "Merchán, M."
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Item Analysis of the behaviour of steel components in contact with AZ91D and AM60 magnesium alloys in HPDC(World Foundry Organization, 2014) Egizabal, P.; Merchán, M.; Corengia, P.; García, C.; Alberdi, M.; Tecnalia Research & Innovation; CIRMETAL; GENERALThe problems encountered in High Pressure Die Casting of magnesium alloys due to the interaction between steel components and the melt alloys are approached. The performance of different steels as well as surface treatments has been compared through a test consisting of the immersion of steel samples in melt AZ91D and AM60. The final objective is to understand the mechanisms of steel degradation through the analysis of the reaction layer and to select the most optimum steel/coating system for magnesium HPDC applications. The materials that are presently used for applications in contact with melt magnesium are usually low carbon stainless steels that do not contain any nickel or copper. Iron reacts with both aluminium and manganese present in magnesium alloys creating an intermetallic reaction layer. Six different steels were selected and tested. It was seen that the main intermetallic layer is composed of Fe2Al5. It is created when AZ91D alloy attacks the Steel and it is thinner in steels with low Mo and V contents. Furthermore the higher the V content the thicker the layer thickness. Subsequently two steels were selected that showed the best performance in the immersion test with the goal of studying different surface treatments that could enhance this performance. The test was repeated with treated samples in both magnesium alloys and a complete microstructural analysis was carried out to understand the reaction mechanisms and select the most appropriate steel alloys. The details of the procedure and results are presented in this work. Following the main conclusions are summarized: It can be said that both PVD and nitriding treatments are capable of minimizing the formation of the intermetallic layer after 3 hours of contact with melt magnesium alloys. The AlCrN coating applied by PVD presents a very good aspect in the case of the 1.2343 steel. It keeps the original thickness and is totally homogeneous all over the surface in contact with the magnesium alloy. The same coating was doped with yttrium and zirconium but no further improvements were appreciated. In the case of the 1.2888 Steel the AlCrN coating presented some cracks after the immersion trial. When doped with Zirconium the cracks did not appear but its thickness diminished and became irregular. Doping with Ytrium did not provide a good behaviour. The coating thickness was irregular and even disappeared in some areas. In the case of the samples treated with the gaseous nitriding process a large porosity was observed into the coatings. This was more evident in the 1.2343 steel. In service conditions these pores could make it possible that Al and Mn diffused through the coating into the substrate with the subsequent formation of the intermetallic layer and loss of properties in the substrate.Item Desarrollo y caracterización de un material compuesto de matriz de aluminio 6061 y partículas de TiB 2(2010) Egizabal, P.; Merchán, M.; García-De-cortázar, M.; Plaza, L. M.; Torregaray, A.; Tecnalia Research & Innovation; CIRMETALThe incorporation of ceramic particles has been one of the ways developed to improve the mechanical properties of aluminium alloys during the last years. The main objective of this work has been to develop the manufacturing process of the reinforced aluminium alloy and analyse its mechanical properties and microstructure. Details about an innovative MMC manufacturing process and the results obtained in the development of a new family of TiB 2reinforced aluminium alloys for forging and extrusion applications are presented. It has been observed that the considered manufacturing process, consisting in the fabrication of particles by SHS and their incorporation into the selected alloy, is a feasible process to manufacture reinforced alloys that can be subsequently extruded or forged. The final result is the development of a material suitable for extrusion and forging applications and that presents an improvement of fatigue and tensile properties of the matrix alloy.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 Estudio de la intercara de una preforma híbrida infiltrada sin presión(2010) Merchán, M.; García De Cortázar, M.; Egizabal, P.; Peñalba, F.; López, A. J.; Torres, B.; Rodrigo, P.; Rams, J.; CIRMETAL; Tecnalia Research & InnovationThis work presents an interfacial characterization of the matrix/reinforcement interface of an aluminium matrix composite reinforced with Saffil fibres and alumina particles was manufactured using the Primex ™ pressureless infiltration process. Scanning electron microscopy and energy dispersive X-ray spectroscopy were used to carry out the microstructural and chemical characterization of the composite material. In addition, a mechanical characterization was conducted by the nanoindentation technique. This research concludes that the composite presents a good bonding between the matrix and the reinforcements.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.