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Ce travail est dédié á l´étude de l´influence de nano-particules de alumina (Al2O3) et de di-borure de titane (TiB2) sur la solidification, la microstructure et les propriétés thermiques et mécaniques de l´alliage d´aluminium renforcés, Al-Si9Cu3Fe1. Les matériaux ont été obtenus par un procédé de fonderie à haute pression en coulant les alliages dans les mêmes conditions que les alliages non renforcés correspondants.On a constaté que les particules de Al2O3 et de TiB2 ont une influence directe sur les caractéristiques de l´alliage telles que la microstructure, la précipitation des phases pendant la solidification et les propriétés mécaniques et électriques. On a ainsi montré que les particules de Al2O3 et de TiB2 peuvent être utilisées pour ajuster les caractéristiques des alliages et obtenir des propriétés spécifiques pour des applications dans les secteurs de matériaux légers. / The work has been focused on the study of the influence of TiB2 and Al2O3 nano-particles (up to 1 wt. %) on the properties and physical features of an aluminium casting alloy, Al-Si9Cu3Fe1.Samples have been obtained through the High Pressure Die Casting (HPDC) process and compared with unreinforced samples obtained at the same conditions. It has been observed that the Al2O3 and TiB2 particles have a direct influence on several features of the alloy such as the microstructure and precipitating phases as well as in the improvement of the soundness and mechanical and electrical properties. Al2O3 and TiB2 particles can be used to tailor the properties of the alloy and to match the specifications of light weight applications

Modern manufacturing processes are under a never ending evolvement. Lowered manufacturing costs, higher part quality, shorter lead times and lower environmental impact are some important drivers for this development. Aluminum die casting is an effective and attractive process when producing components for e.g. the automotive sector. Die casting process development, and hot work tool steel development for the die casting dies has led to the state of the art of die casting today. However, with the disruptive emergence of Additive Manufacturing (AM) of hot work steel alloys, new interesting features such as improved conformal cooling channels inside die casting molds can be produced. The new way to manufacture die casting dies, need basic investigating of the AM produced hot work tool steel properties, and their applicability in this demanding hot work segment. Die casting dies face several detrimental wear mechanisms during use in production, three of which has been isolated and used for testing three AM produced steel alloys and one conventional premium hot work tool steel. The wear mechanisms simulated are; thermal fatigue, static soldering and agitated soldering. The aim is to study the AM produced steels applicability in the die casting process. The tested materials are; Premium AISI H13 grade Uddeholm Orvar Supreme, AM 1.2709, AM UAB1 and AM H13. Based on current investigations the conclusion that can be made is that with right chemistry, and right AM processing, conventional material Uddeholm Orvar Supreme still is better than AM H13. This also complies with the literature study results, showing that conventional material still is better than AM material in general. / Våra moderna tillverkningsprocesser är under ständig utveckling. Drivande motiv är minskade tillverkningskostnader, högre tillverkningskvalitet, kortade ledtider samt minskad miljöpåfrestning. Pressgjutning av aluminium är en effektiv och attraktiv tillverkningsprocess ofta använd inom till exempel fordonsindustrin. Utvecklingen av pressgjutningsteknologin har gått hand i hand med utvecklingen av det varmarbets-verktygsstål som används i gjutformarna (pressgjutningsverktyget). Den utvecklingen har lett till dagens processnivå och branschstandard. Men med den revolutionerande additiva tillverkningsteknologins (AM) intåg, och möjlighet att producera komponenter av varmarbetsstål, kommer nya intressanta möjligheter att integrera komplex geometri så som yt-parallella kylkanaler i verktyget utan att tillverkningskostnaden blir för hög etc. Det nya sättet att producera pressgjutningsverktyg ger upphov till behovet av grundläggande materialundersökningar av sådant AM-material, samt hur tillförlitligt det är i pressgjutningsverktyg med pressgjutningens krävande materialegenskapsprofil. Pressgjutningsverktyg utsätts för många förslitningsmekanismer och för höga laster, tre av dessa mekanismer har isolerats för kontrollerade tester av ett konventionellt material och tre AM materials responser. Förslitningsmekanismerna som efterliknats är; termisk utmattning, statisk soldering och agiterad soldering. Målet med undersökningarna är att studera AM producerade materials lämplighet i pressgjutningsprocessen. De material som testats är konventionella premium varmarbetsstålet Uddeholm Orvar Supreme av typ AISI H13, AM 1.2709, AM UAB1 och AM H13. Undersökningarnas slutsats är att med rätt kemisk sammansättning, och med rätt AM printing parametrar, är konventionellt material fortfarande mer applicerbart i pressgjutning än AM producerat. Den slutsatsen faller väl I samklang med resultaten från mekanisk provning som återspeglas i litteraturstudien, som visade visar att konventionellt material är generellt bättre än AM material.

Today, there is an essential need for lightweight, energy-efficient, environmentally benign engineering systems, and this is the driving force behind the development of a wide range of structural and functional materials for energy generation, energy storage, propulsion, and transportation. These challenges have motivated the use of magnesium alloys for lightweight structural systems. Magnesium has a density of 1.74 g/cm3, which is almost 30% less than that of aluminium, one quarter of steel, and almost identicalto polymers. The ease of recycling magnesium alloys as compared to polymers makes them environmentally attractive, but their poor mechanical performance is the primary reason for the limited adoption of these alloys for structural applications. The Mg-Al-Zn alloy AZ91D exhibits an excellent combination of strength, die-castability, and corrosion resistance. However, its mechanical performance with regard to creep strength, for example, at evaluated temperatures is poor. Moreover, very little is known about the correlation between its mechanical properties and microstructural features. This thesis aims to provide new knowledge regarding the role played by microstructure in the mechanical performance of the magnesium alloy. The properties/performance of the material in relation to process parameters became of great interest during the investigation. An exhaustive characterisation of the grain size, secondary dendrite arm spacing (SDAS) distribution, and fraction of Mg17Al12 was performed using optical and electron backscatter diffraction (EBSD). These microstructural parameters were correlated to the offset yield point (Rp0.2), fracture strength, and elongation to failure of the material. It was proposed that the intermetallic phase, Mg17Al12, plays an important role in determining the mechanical and physical properties of the alloy in a temperature range of room temperature to 190°C by forming a rigid network of intermetallic. The presence of this network was confirmed by studying the thermal expansion behaviour of samples of the alloy containing different amounts of Mg17Al12. A physically based constitutive model with a wide validity range was successfully adapted to describe the flow stress behaviour of AZ91D with various microstructures. The temperature-dependent variables of the model correlated quite well with the underlying physics of the material. The model was validated through comparison with dislocation densities obtained using EBSD. The influence of high-pressure die-cast parameters on the distortion and residual stress of the cast components was studied, as were distortion and residual stress in components after shot peening and painting. Interestingly, it was found that intensification pressure has a major effect on distortion and residual stresses, and that the temperature of the fixed half of the die had a slight influence on the component's distortion and residual stress. / Numera finns det ett väsentligt behov av lätta, energieffektiva och miljövänliga tekniksystem. Detta behov är drivkraften för utveckling av ett brett utbud av material för energigenerering, energilagring, framdrivning och transport. Dessa utmaningar motiverade användningen av magnesiumlegeringar för lättviktskonstruktioner. Magnesium har en densitet på 1,74 g/cm3, vilket är ca 30% lägre än för aluminium, en fjärdedel av densiteten för stål och nästan i nivå med många polymerer. Då magnesiumlegeringar dessutom är lätta att återvinna, jämfört med polymerer, gör det dem miljömässigt attraktiva. Låga mekaniska egenskaper är den främsta orsaken till begränsad användning av dessa legeringar för lastbärande tillämpningar. Mg-Al-Zn-legeringen AZ91D uppvisar en utmärkt kombination av styrka, gjutbarhet och korrosionsbeständighet. Dess mekaniska egenskaper vid förhöjd temperatur, som tex kryphållfasthet, är låga. Dessutom är korrelationen mellan mikrostruktur och mekaniska egenskaper oklar. Denna avhandling syftade till att ge ny kunskap om mikrostrukturens roll för magnesiumlegeringars mekaniska egenskaper. Slutligen var materialets egenskaper i förhållande till processparametrar vid tillverkningen av stort intresse. En omfattande karaktärisering av kornstorleks-, sekundära dendritarmavstånds (SDAS)-fördelning och fraktion av Mg17Al12 utfördes med hjälp av optisk mikroskopering och diffraktion av bakåtspridda elektroner (EBSD). Mikrostrukturen korrelerades till sträckgränsen (Rp0.2), brottstyrkan och brottförlängningen. Det föreslogs att den intermetalliska fasen, Mg17Al12, spelar en viktig roll vid bestämning av legeringens mekaniska och fysikaliska egenskaper vid temperaturintervall från rumstemperatur upp till 190°C genom att bilda ett styvt nätverk av intermetaller. Uppkomsten av ett sådant nätverk stöddes genom en studie av den termiska expansionen av legeringen för olika fraktioner av Mg17Al12. En fysikalisk konstitutiv modell med ett brett giltighetsområde användes framgångsrikt för att beskriva det plastiska flytbeteendet hos AZ91D för olika mikrostrukturer. De temperaturberoende variablerna i modellen korrelerade ganska väl med materialets underliggande fysik. Modellen validerades genom att jämföra dislokationstätheten som predikterades av modellen och den med EBSD uppmätta dislokationstätheten. Påverkan av pressgjutningsparametrar på geometrisk tolerans och restspänning hos de gjutna komponenterna studerades. Vidare studerades geometrisk tolerans och restspänning av komponenter efter pening och målning. Intressant nog hade eftermatningsfasen en stor effekt på geometrisk tolerans och restspänningar. Dessutom hade temperaturen på den fasta formhalvan av verktyget även ett visst inflytande på komponentens geometriska tolerans och restspänning.

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The diploma thesis is focuses on new technology in of high pressure die casting industry. Attention is paid in particular to heating, cooling and the influence of the die lubricants on the quality of castings. theoretical knowledge was applied in practise. The optimization of the production cycle was carried out using a high temperature die lubricant and subsequent evaluation on particular casts in foundry KOVOLIT Modřice a.s.

Kongsberg Automotive is developing a brand-new actuator for engaging and disengaging a clutch for different driveline applications. This master thesis research improves the concept design of the shift fork for the new Dog-Clutch Actuator using Design for Manufacturability (DFM). Initially, the knowledge about the mechanism of the product is gained with the aid of the design team and the proper boundary conditions for the boundary value problem are obtained. The conventional die-cast materials are investigated, and appropriate material is selected to create the material model. Most of the traditional HPDC aluminum alloys are aluminum-silicon system; therefore, a detailed study on the nucleation of Silicon in the melt and how it influences the mechanical properties of the alloy is conducted. During gear engagement, the two rotating gears of the dog-clutch collide and synchronize the angular velocity of the hub and the input gear. The synchronization force is dynamic; therefore, explicit time integration is used to capture the system's response with the assistance of FEM software. As the shift fork undergoes cyclic load during the gear shift, the fatigue analysis is performed to evaluate the life (Nf) of the component using Wohler's curve. The value of the maximum principal stress at the critical spots like notch and its direction are determined using the 3D Mohr's circle. In this analysis, the endurance limit correction factors and notch factor (Kf) are used for the S-N curve correction, and Goodman's criteria are used to incorporate the mean stress effect. Fatigue analysis requires a very fine mesh to estimate the precise stress magnitude at the critical locations and, the structural optimization algorithm requires many iterations to determine the optimal layout of the shift fork. Therefore, the explicit integration scheme is not efficient as it will be computationally expensive and time-consuming to solve the problem. Hence, the equivalent static load is determined for the gear shift force at the peak load and used for calculations and product development. As the initial concept design of the shift fork is asymmetrical, it requires varying stiffness in its structure to transfer the force efficiently to the shift sleeve. The FEA results state that one prong of the shift fork experience up to 75% of the total load, which increases the overall stress of the component (up to 0.9Sy). The shift fork also doesn't have adequate torsional stiffness, and as a result, stress concentration has occurred in one of the fillets in the shift fork. The iterative design is set up to improve the design of the shift fork by optimizing the stiffness of the two prongs which provided the key observations that describe the design changes which improved the design. In this phase, the overall stress of the component is reduced by 20% and minimizes the difference in the load between the two prongs by 27.5% compared to the initial design. The shift fork needs to be light to achieve the necessary acceleration during the gear shift. Therefore, topology optimization using the projected subgradient method is implemented to optimize the mass and compliance of the improved design in the iterative design phase. Then the design realization phase is set up to implement the results obtained from the topology optimization to conceptualize the viable product. The optimized result decreased the overall stress and maximum deflection by 20%. It also reduced the load difference in the two prongs of the shift fork by 35% by maintaining the same mass as the initial concept design.

The project aim is an optimalization of production of pressure die casting, which serves as a one part of handle in office furniture area. The main emphasis was for mass finishing operation, which serves for rounding of very sharp part edges after die casting operation. A few tests of single mass finishing parameter was carried out and as result was a few partial recommendations for an increasing of production efficiency and improving of manufacturing process, namely an adjustment of separation cycle, proposal of optimum amount of pieces in each single batch and an innovation of chips type and dimensions. The project includes a proposal of a new and more efficiency layout of pieces on the transport pallet.

The purpose of this diploma thesis is comparing the quantity of porosity in die-cast aluminium casting with using simulation. The cast engine blocks were made by high pressure die-casting and a local squeeze casting (LSC) technology. There was also examined the relationship between porosity and mechanical properties of castings. There were evaluated and compared the results of my own measurements with data from previous students theses at the Faculty of Mechanical Engineering BUT. All data were tested by statistical tests. The comparison of simulation results and experimentally measured values was found a good programme-ability to simulate and estimate porosity.

Im Rahmen der Arbeit wurde das Potential von Magnesium für den Einsatz im Fahrwerk eines Automobils, am Beispiel der Querbrücke des Hinterachsträgers, ermittelt. Verschiedene Mg-Legierungen wurden im konventionellen und vakuumunterstützen Druckguss vergossen und der Al-Legierung vergleichend gegenübergestellt. Es wurden in einem ersten Schritt statische und zyklische Werkstoffkennwerte sowie Materialmodelle erforscht und bewertet. Verschiedene Lastfälle im Standard- und Sonderfahrbetrieb wurden durch statische und zyklische Betriebsfestigkeitssimulationen abgesichert. Konstruktive Bauteiloptimierungen waren notwendig um den Werkstoff Magnesium an die Anforderungen der Querbrücke anzupassen. Äußere Umwelteinflüsse im Fahrbetrieb machten ein Korrosionsschutzkonzept für die Querbrücke aus Magnesium notwendig. Untersucht wurden dabei verschiedene Maßnahmen zur Vermeidung von Kontakt- und Oberflächenkorrosion. Grundsätzlich scheint der Einsatz von Magnesium im Fahrwerk im Bereich mittlerer Betriebsbelastungen denkbar.