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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Invest to perform internally versus outsourcing of metal additive manufacturing : An exploratory case study

Johansson, Robert, Rindom Brinter, Sonny January 2019 (has links)
Firms often stand before decisions on whether to make or buy components. Various well-established theories that have been applied and developed to understand make or buy decisions have also been critiqued for not generating a well-based decision basis. Research indicates that make or buy decisions are more complex than most theories suggest and that theories within make or buy don’t seem to account for situations when the production technology does not exist in-house. In instances of new technology, in this case metal AM, there is a need to understand and account for the case specific attributes to determine the best course of action. This study explores the decision situation of invest to perform internally versus outsourcing of metal additive manufacturing. The aim is to investigate and identify what factors affect the decision. The research design is a qualitative exploratory case study including 10 interviews and a cost analysis of two products, to answer how metal additive manufacturing affects these decisions. The cost analysis is included, as economic performance is a factor of importance, which makes it meaningful to understand in such situations. The most prominent factors in the result are found to be competency, control, economy, interaction, organization and strategy. The results of the study indicate overlapping similarities of the results through existing theories and suggest that these decisions are more complex than the individual application of single theories. However, the cost analysis shows that the currently held outsourcing alternative is more expensive and this might indicate a non-rational decision in regards to the financial perspective. The main contribution of this study is to the field of decision-making with the conclusion of that individual theories are not sufficient to explain the phenomenon of invest to perform internally versus outsourcing. To evaluate these decisions, the results indicate the necessity to have a multi-criteria approach and include several theoretical perspectives.
82

Experimental and Theoretical Investigation of Selective Laser Melted Uddeholm Dievar ®

Pepić, Sanjin, Ridemar, Otto January 2019 (has links)
The main problem encountered in this thesis is the lack of research and knowledge of selective laser melted-printing with Uddeholm Dievar®. This absence of information could cause issues regarding quality and properties of the alloy as well as uncertainty regarding an appropriate heat treatment cycle. This thesis mainly focuses on observing the changes that occur in the microstructure when Uddeholm Dievar® is manufactured through the additive manufacturing (AM) method known as selective laser melting (SLM). The SLM- method consists of a high-power laser that melts together thin layers of powder, one layer at a time, until a three-dimensional product is created according to selected drawings. The methodology on which this thesis is based on is the execution of a theoretical study, scientific experiments and thermodynamic calculations. Analysis of the microstructure is performed using a scanning electron microscope with techniques such as Energy-dispersive X-ray spectroscopy (EDS) and Electron backscatter diffraction (EBSD). The purpose of the methods are to map the constituent elements of the alloy and observe the orientation of the crystallographic phases in the atomic lattice respectively. The results show that the powder, both before and after printing, mainly consists of martensite with a low amount of residual austenite. The amount of primary carbides is relatively low and has been classified as MC (V-rich) and/or M6C (Mo- rich) type. The remaining residual austenite could be explained by the segregation of constituent alloying elements, where the carbon content is a dominant factor to why the MS -temperature lowers significantly causing the presence of retained austenite even though SLM has a cooling rate that varies between 103 and 108 [K/s]. / Det huvudsakliga problemet som denna avhandling behandlar är bristen på forskning och kunskap inom selective laser melting (SLM) 3D-printing med Uddeholm Dievar®. Avsaknaden kan leda till sämre kvalité och produktegenskaper hos legeringen. Det kan även leda till ovisshet gällande val av lämplig värmebehandling. Arbetet fokuserar på att dokumentera utformningen av stålets mikrostruktur när Uddeholm Dievar® tillverkas med den additiva tillverkningsmetoden SLM. Tillverkningsprocessen består av en högeffektslaser som detaljerat smälter samman tunna lager pulver, ett lager i taget, tills att en tredimensionell produkt skapats utefter valda ritningar. Använda metoder är; utförandet av en teoretisk studie, vetenskapliga experiment och thermodynamiska beräkningar. Analys av mikrostrukturen genomförs med hjälp av svepelektronmikroskåp där teknikerna Energy-dispersive X-ray spectroscopy (EDS) och Electron backscatter diffraction (EBSD) används. Syftet med EDS är att kartlägga de ingående elementen i legeringen, syftet med EBSD är att se orientering av de kristallografiska faserna i atomgittret. Resultaten visar på att legeringen, både före och efter printing, till största del består av martensit med en låg mängd restaustenit. Mängden primärkarbider är relativt låg och har klassifiserats som typen MC (V-rik) och/eller M6C (Mo- rik). Den kvarstående restausteniten kan möjligen förklaras av segringen av ingående legeringsämnen där kolhalten är en dominerande faktor som sänker MS-temperaturen. Detta gör att restaustenit förekommer trots den höga kylhastigheten som varierar mellan 103 och 108 [K/s] i SLM.
83

Thermal fatigue and soldering experiments of additively manufactured hot work tool steels

Andersson, Henrik January 2018 (has links)
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.
84

Additiv tillverkning för högre teknisk tillgänglighet i internationella insatsområden

Pettersson, Alexander January 2018 (has links)
In this paper the military utility of additive manufacturing of spare parts during international deployment is explored. We also analyze the effect that additive manufacturing has on technical availability. International deployment can be tough for logistical reasons and this leads to a difficulty in supplying ground troops with spare parts. If the spare parts cannot be acquired in the deployment area these have to be shipped from central distribution centers or be ordered directly from the industries. Some spare parts are uncommon and not stored in distribution centers but only get manufactured on order. This type of production can lead to delivery times of up to 40-50 weeks. With additive manufacturing this process could be shortened to 4-10 weeks. Conclusions that can be drawn is that additive manufacturing has military utility and can give a higher technical availability, given that a few technical difficulties are resolved. At this point there is a shortcoming in the number of qualified materials for printing spare parts for regular vehicles and this makes it difficult for the industry to approve of spare parts constructed with additive manufacturing. The winning in technical availability is directly linked to how difficult the deployment area is to reach for logistical units. Additive manufacturing has a higher positive effect in areas that are hard to reach. / I denna uppsats undersöks den millitära nyttan med additiv tillverkning av reservdelar för markförband under internationell insats och hur detta kan påverka den tekniska tillgängligheten på systemen. Internationella insatser kan kräva långa logistikkedjor vilket innebär att reservdelar som inte kan införskaffas i närområdet måste fraktas från en bakre underhållsnivå eller beställas direkt från leverantör. Vid vissa tillfällen med skador på system som kräver nyproduktion av reservdelar från tillverkare, kan det i dagsläget ta upp till 40-50 veckor. Med additiv tillverkning kan förloppet kortas ner betydligt och tillverkningstiden blir istället 4-10 veckor. Slutsatser som kan dras är att additiv tillverkning har en militär nytta och kan ge en högre teknisk tillgänglighet, förutsatt att en del tekniska svårigheter klaras ut. I dagsläget finns det brister i mängden kvalificerade material för utskrifter till vanliga fordon vilket gör det svårt för industrin att godkänna reservdelarna som en ordinarie reparationsmetod i sina produkter. Vinsten i teknisk tillgänglighet är också kopplad till hur svårtillgängligt insatsområdet är. Desto svårtillgängligare området är desto större vinst medför additiv tillverkning.
85

Testing and evaluation of component made using electron beam melting and Alloy 718 powder

Nilsson, Erik, Johansson, Daniel January 2017 (has links)
The aerospace industry is constantly striving to becoming more economical and environmentally friendly. One of many efforts to achieve this is the Lightcam project which in this case is evaluating the use of additive manufacturing in the form of electron beam melting in conjunction with the nickel-based superalloy, Alloy 718. This combination is not fully explored and examined. For this purpose, a demonstrator vane was produced and it was subsequently evaluated in this thesis. The evaluation was performed in as-built condition and was divided in non-destructive testing, evaluation of these methods and metallographic review to confirm the results, and potentially revealing more properties. The non-destructive testing was performed using conventional radiography and computed tomography. Both methods struggled to deliver complete and reliable results, for varying reasons. Radiography could deliver results of the whole vane, but these were impossible to evaluate due to the rough surface created by the electron beam melting process. The computed tomography on the other hand was not affected by the rough surface and produced usable, though not complete, results of the vane. The reason for the computed tomography’s inability to deliver complete results was the material, varying thickness and complex geometry of the vane. As a complement and to verify the results from the non-destructive testing, a metallographic examination was conducted. These tests were conducted with the aim of answering the following three questions:  What non-destructive testing methods are suitable to evaluate Alloy 718 components manufactured with electron beam melting? - Neither radiography nor computed tomography are suitable as a sole evaluation method, for various reasons. All surface dependent methods were deemed unsuitable without testing due to the rough surface. What types of defects and in what quantity can they be found in the produced vane? - Defects found are: Porosity and lack of fusion, both found as internal and partially external and in varying sizes. Where are the defects located? - Pores are mainly found in the center of sections modeled to a 3mm thickness. Lack of fusion was found between build layers in all thicknesses. Apart from these results, hardness was found to vary depending on build height, increasing from the bottom towards the top. Microstructure was also found to vary with the build height, but always consisting of either equiaxed or columnar grains. / Lightcam
86

Participatory design of a 3D-printed furniture concept for learning spaces : A study of large-scale additive manufacturing opportunities and limitations

Lundgren, Herman January 2021 (has links)
Today, learning spaces are stuck in the industrial age with rows of desks and chairs. Differentiated teaching and personalised learning are not effective in traditional learning spaces and should focus on creating future classrooms (Kariippanon, 2017). This thesis is covering how furnishing for learning environments can be improved and designed through a participatory design process with Katedralskolan in Växjö by using recycled materials and additive manufacturing technology. The thesis is also exploring the opportunities of involving stakeholders to create new learning through the additive manufacturing process in interior and furniture design. Together with Katedralskolan and Sculptur, this project is exploring a concept for schools to have integrated education in interior design through semiotics that will contribute to students’ learning and explore large-scale additive manufacturing. The objective is to design a collection of interior products that will inform and communicate at an educational level and how a circular manufacturing technique is possible through 3D-printing using communicating design and semiotics. The aim is also to understand Sculptur’s product development- and manufacturing process through large-scale 3D-printing. The mission statement whereas follows: Develop a furniture concept based on an understanding of the needs of, and participation with, the user group in a co-design process as a case to study the large-scale additive manufacturing techniques together with the given conditions provided by Sculptur. The thesis process has been following an iterative design process called the design thinking process (The Interaction Design Foundation, 2021) and a co-designing process (Sanders, 2018). The design thinking process is a design methodology that provides a solution-based approach to solving problems. The five stages of Design Thinking are as follows: Empathise, Define, Ideate, Prototype, Test. Through studies, surveys, and observations a list of stakeholder needs was created and was used when developing ideas through workshops, drawings, and prototyping. The ideas were then developed into concepts that were tested through both desktop 3D-printing and large-scale additive manufacturing. The concepts were also evaluated by stakeholders as well as through a concept evaluating matrix (Wikberg N., et.al., 2015). The result of this master thesis is the conclusion of the furniture concept as well as the study of large-scale additive manufacturing as an industrial designer. The furniture concept “Unfold lounge chair” is based on stakeholder needs and manufacturing restrictions. It is also an attempt to use theory to make the next generation of pedagogical furnishings using sustainable and circular manufacturing techniques. Through design thinking, the master thesis result was created with a human-centred approach to integrate the needs of people, the possibilities of technology and the requirements for business success (IDEO, n.d.). / Idag sitter läromiljöer fast i den industriella epoken med rader av skrivbord och stolar. Differentierad undervisning och personlig inlärning är inte effektiv i traditionella läromiljöer och bör vara i fokus för att skapa framtidens klassrum (Kariippanon, 2017). Detta examensarbete tar upp hur inredning för inlärningsmiljöer kan förbättras och utformas genom en deltagande designprocess med Katedralskolan i Växjö med hjälp av återvunna material och additiv tillverkningsteknik. Arbetet har också undersökt möjligheterna att involvera intressenter för att skapa nytt lärande genom tillämpning av additiv tillverkning inom inredning och möbeldesign. Tillsammans med Katedralskolan och Sculptur har detta projekt undersökt ett koncept för skolor att ha integrerad utbildning i möbler genom semiotik och pedagogisk design som kommer att bidra till elevernas lärande samt utforska storskalig additiv tillverkning. Målet är att utforma en samling möbelkoncept som informerar och kommunicerar på utbildningsnivå och hur en cirkulär tillverkningsteknik är möjlig genom 3D-printnig med hjälp av kommuniationsdesign och semiotik. Målet är också att förstå Sculpturs produktutvecklings- och tillverkningsprocess genom storskalig additiv tillverkning. Projektets Mission statement var följande: Utveckla ett möbelkoncept baserat på en förståelse av behoven hos användargruppen i en samdesignprocess som ett fall för att studera storskalig additiv tillverkning tillsammans med de givna förutsättningarna från Sculptur. Examensarbetet har följt en iterativ designprocess som kallas design thinking process (The Interaction Design Foundation, 2021) tillsammans med en co-designprocess (Sanders, 2018). Design thinking är en designmetodik som ger en lösningsbaserad metod för att lösa problem. De fem faserna i design thinking är följande: Empathise, Define, Ideate, Prototype, Test. Genom studier, undersökningar och observationer skapades en lista över intressenters behov och användes när idéer utvecklades genom workshops, skisser och prototyper. Idéerna utvecklades sedan till koncept som sedan testades genom både mindre 3D-utskrift och storskalig additiv tillverkning. Koncepten utvärderades också av intressenter samt genom en konceptviktningsmatris (Wikberg N., et.al., 2015). Resultatet av detta examensarbete är sammanfattningen av möbelkonceptet samt studien av storskalig additiv tillverkning som industridesigner. Möbelkonceptet ”Unfold lounge chair” bygger på intressenternas behov samt tillverkningsrestriktioner. Det är också ett försök att använda teori för att skapa nästa generation av pedagogiska möbler med hållbara och cirkulära tillverkningstekniker. Genom design thinking skapades resultatet med ett mänskligt centrerat tillvägagångssätt för att integrera människors behov, teknikens möjligheter och kraven för produktens framgång (IDEO, n.d.).
87

Process Mapping for Laser Metal Deposition of Wire using Thermal Simulations : A prediction of material transfer stability / Processkartläggning för lasermetalldeponering av tråd baserat på termiska simuleringar : En prediktering av materialöverföringsstabilitet

Lindell, David January 2021 (has links)
Additive manufacturing (AM) is a quickly rising method of manufacturing due to its ability to increase design freedom. This allows the manufacturing of components not possible by traditional subtractive manufacturing. AM can greatly reduce lead time and material waste, therefore decreasing the cost and environmental impact. The adoption of AM in the aerospace industry requires strict control and predictability of the material deposition to ensure safe flights.  The method of AM for this thesis is Laser Metal Deposition with wire (LMD-w). Using wire as a feedstock introduces a potential problem, the material transfer from the wire to the substrate. This requires all process parameters to be in balance to produce a stable deposition. The first sign of unbalanced process parameters are the material transfer stabilities; stubbing and dripping. Stubbing occurs when the energy to melt the wire is too low and the wire melts slower than required. Dripping occurs when too much energy is applied and the wire melts earlier than required.  These two reduce the predictability and stability that is required for robust manufacturing.  Therefore, the use of thermal simulations to predict the material transfer stability for LMD-w using Waspaloy as the deposition material has been studied.  It has been shown that it is possible to predict the material transfer stability using thermal simulations and criterions based on preexisting experimental data. The criterion for stubbing checks if the completed simulation result produces a wire that ends below the melt pool. For dripping two criterions shows good results, the dilution ratio is a good predictor if the tool elevation remains constant. If there is a change in tool elevation the dimensionless slenderness number is a better predictor.  Using these predictive criterions it is possible to qualitatively map the process window and better understand the influence of tool elevation and the cross-section of the deposited material. / Additiv tillverkning (AT) är en kraftigt växande tillverkningsmetod på grund av sin flexibilitet kring design och möjligheten att skapa komponenter som inte är tillverkningsbara med traditionell avverkande bearbetning.  AT kan kraftigt minska tid- och materialåtgång och på så sett minskas kostnader och miljöpåverkan. Införandet av AT i flyg- och rymdindustrin kräver strikt kontroll och förutsägbarhet av processen för att försäkra sig om säkra flygningar.  Lasermetalldeponering av tråd är den AT metod som hanteras i denna uppsats. Användandet av tråd som tillsatsmaterial skapar ett potentiellt problem, materialöverföringen från tråden till substratet. Detta kräver att alla processparametrar är i balans för att få en jämn materialöverföring. Är processen inte balanserad syns detta genom materialöverföringsstabiliteterna stubbning och droppning. Stubbning uppkommer då energin som tillförs på tråden är för låg och droppning uppkommer då energin som tillförs är för hög jämfört med vad som krävs för en stabil process. Dessa två fenomen minskar möjligheterna för en kontrollerbar och stabil tillverkning.  På grund av detta har användandet utav termiska simuleringar för att prediktera materialöverföringsstabiliteten för lasermetalldeponering av tråd med Waspaloy som deponeringsmaterial undersökts. Det har visat sig vara möjligt att prediktera materialöverföringsstabiliteten med användning av termiska simuleringar och kriterier baserat på tidigare experimentell data. Kriteriet för stubbning kontrolleras om en slutförd simulering resulterar i en tråd som når under smältan.  För droppning finns två fungerande kriterier, förhållandet mellan svetshöjd och penetrationsdjup om verktygshöjden är konstant, sker förändringar i verktygshöjden är det dimensionslös ”slenderness” talet ett bättre kriterium.  Genom att använda dessa kriterier är det möjligt att kvalitativt kartlägga processfönstret och skapa en bättre förståelse för förhållandet mellan verktygshöjden och den deponerade tvärsnittsarean.
88

Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting

Thalavai Pandian, Karthikeyan January 2022 (has links)
Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility vi programvaran NASGRO där livsförutsägelserna visade god överensstämmelse med experimentella livscykler i de flesta fall. vii Abstract Title: Microstructure and mechanical properties of low-temperature hot isostatic pressed Ti-6Al-4V manufactured by electron beam melting Keywords: Additive manufacturing, high-temperature tensile properties, low cycle fatigue, neutron diffraction, fatigue crack growth ISBN: 978-91-89325-27-2 (Printed) 978-91-89325-26-5 (Electronic) Ti-6Al-4V is the most widely used α+β titanium alloy in aerospace engine applications due to its high specific strength. Typically, the alloy is manufactured as castings or forgings and then machined to final geometry. These conventional manufacturing processes do however generate a lot of waste material, whereas additive manufacturing (AM) can potentially produce a near-net-shape geometry directly from the feedstock. In the past decade, electron beam melting (EBM), one of the powder bed fusion techniques, has been widely researched to build Ti[1]6Al-4V components. Still, the as-built material can contain defects such as gas pores that require post-processing, such as hot isostatic pressing (HIP) to produce nearly fully dense components. HIP treatment of conventionally cast Ti-6Al-4V is normally performed at 920 ˚C, 100 MPa for 2 hours. This same HIP treatment has then been adapted also for EBM-manufactured Ti-6Al-4V, which however results in coarsening of α laths and reduction of yield strength. Therefore, finding a more appropriate HIP treatment for this new type of Ti-6Al-4V material, i.e. EBM manufactured, would be of great benefit for the industry. Lowering the HIP treatment temperature to 800 ˚C and increasing the pressure to 200 MPa has recently been proven to close the porosity to a high degree while sustaining the high yield strength. In this thesis, the high-temperature tensile properties of EBM-manufactured Ti[1]6Al-4V subjected to a low-temperature (800 ˚C) HIP treatment were evaluated and compared with standard HIP-treated (920 ˚C) materials. Metallurgical characterization of the as-built, HIP-treated materials have been carried out to understand the effect of temperature on the microstructures. The standard HIP[1]treated material measured about 1.4x - 1.7x wider α laths than those in the low[1]temperature HIP treated and as-built samples, respectively. The standard HIP[1]treated material showed about 10 - 14% lower yield strength than other HIP treated materials. At 350 ˚C the yield strength decreases to about 65% compared to the room temperature strength for all tested materials. An increase in ductility viii was observed at 150 ˚C compared to that at room temperature, but the ductility decreased between 150 - 350 ˚C because of activation of different slip systems. The low cycle fatigue (LCF) behavior of such a modified HIP (low-temperature HIP) material is assessed at two different strain levels and compared with the corresponding LCF properties for the standard HIP material. Even though the modified HIP material had lowest minimum life cycles to failure, the overall fatigue performance is comparable with that of the standard HIP material. Also, fatigue life predictions were made from the measured defect size at the crack initiation site using NASGRO. The calculated life predictions showed good agreement with the experimental values in most cases. In-situ neutron diffraction measurements on tensile test specimens were conducted, at both room temperature and at 350˚ C, for the standard and modified HIP-treated materials. The objective was to gain essential insights on how the crystal lattice strains relate to the macroscopic strengths in these specific microstructures. This investigation helped to understand the load partitioning between different slip planes and constituent phases in the microstructure at different temperatures. / Ti-6Al-4V är den mest använda α+β titanlegeringen i flygmotortillämpningar på grund av sin höga specifika hållfasthet. Vanligtvis tillverkas legeringen som gjutgods eller smide och bearbetas sedan till slutlig geometri. Dessa konventionella tillverkningsprocesser genererar dock en hel del avfallsmaterial, medan additiv tillverkning (AM) potentiellt kan producera en nästan slutgiltlig geometri direkt från råvaran. Under det senaste decenniet har elektronstrålesmältning (EBM), en av pulverbäddsfusionsteknikerna, undersökts mycket för att bygga Ti-6Al-4V-komponenter. Ändå kan det byggda materialet innehålla defekter såsom gasporer som kräver efterbearbetning, såsom varm isostatisk pressning (HIP) för att producera nästan helt täta komponenter. HIP[1]behandling av konventionellt gjutet Ti-6Al-4V utförs normalt vid 920 ˚C, 100 MPa under 2 timmar. Samma HIP-behandling har sedan anpassats även för EBM[1]tillverkat Ti-6Al-4V, vilket dock resulterar i förgrovning av α-lameller och minskning av sträckgränsen. Att hitta en mer lämplig HIP-behandling för denna nya typ av Ti-6Al-4V-material, dvs EBM-tillverkat, skulle därför vara till stor fördel för industrin. Att sänka HIP-behandlingstemperaturen till 800 ˚C och öka trycket till 200 MPa har nyligen visat sig stänga porositeten i hög grad samtidigt som den höga sträckgränsen bibehålls. Ti-6Al-4V används huvudsakligen i applikationer för flygmotorer upp till en maximal driftstemperatur på 300 ˚C. Därför studerades högtemperaturdragegenskaperna hos de olika HIP-behandlade EBM[1]byggmaterialen i detta forskningsarbete. Denna studie visade att duktiliteten påverkas av aktiveringen av olika glidsystem baserat på temperatur. Ytterligare neutrondiffraktionsexperiment utfördes tillsammans med in-situ dragprovning för att bestämma det aktiva glidsystemet vid en specifik temperatur. Utmattningsbeteendet hos det lågtemperaturbehandlade HIP-materialet utvärderas också genom lågcykelutmattningstestning och utmattningsspricktillväxttest. Utmattningsprestandan för det modifierade HIP[1]materialet utvärderades mot standard HIP- material och visade sig ha jämförbara utmattningsegenskaper. Förutsägelser om utmattningsliv utfördes med hjälp av vi programvaran NASGRO där livsförutsägelserna visade god överensstämmelse med experimentella livscykler i de flesta fall. / <p>Submitted papers or manuscripts have been excluded from the fulltext file.</p>
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Corrosion of additively manufactured magnesium alloy WE43 : An investigation in microstructure and corrosion properties of as built samples manufactured with Powder Bed Fusion-Laser Beam

Wahman, Clarence January 2021 (has links)
The work presented in this thesis was conducted at Uppsala University and at Swerim AB. The study aims to broaden the knowledge about the corrosion of additively manufactured bioresorbable alloy WE43 in humanlike conditions for future applications. Biodegradable metal implants are implants meant to stay in the body and support the wounded bone for a certain time period, and then degrade as new, healthy bone forms in its place. Magnesium alloys have properties that are desired for these kind of implants as it is biodegradable, non-toxic and matches the mechanical properties of bone. Furthermore, magnesium alloy WE43, containing yttrium, neodymium and zirconium, already exist on the market as a powder extruded screw that treats Hallux valgus, thus proves the alloys compatibility as a bioresorbable implant. However, in order to optimize implants for specific situations, additive manufacturing can be a powerful tool. By utilizing the advantages of additive manufacturing, patient specific, complex designs implant can be manufactured rapidly in order to be used in a patient. On the other hand, additive manufacturing is a complex method with many aspects affecting the outcome. Therefore it is important to study the influence that different parameters have on the material's properties, especially the corrosion properties. This thesis aims to study different power settings on the laser in the manufacturing process and what effect it has on the microstructure as well as the corrosion properties of as built WE43 samples. Samples of three different parameters settings were manufactured with a Powder Bed Fusion-Laser Beam 3Dprinter. These samples were analyzed regarding surface roughness and microstructure with Light Optical Microscope, Scanning Electron Microscope, Energy Dispersive Spectroscopy, Electron Backscatter Diffraction and Alicona InfiniteFocus. Furthermore, the corrosion properties of the samples were investigated by collecting and measuring hydrogen gas that is released during the corrosion process. In addition, the electrolyte were examined regarding the change in ion concentration and electrochemical tests were performed. It was found that the samples did not differ substantially in microstructure as all three parameter settings exhibited a matrix of magnesium and precipitates of alloying elements. However, the sample manufactured at the lowest energy density had pores incorporated in the bulk. Despite the porous bulk this sample performed best in the immersion tests and exhibited the lowest corrosion rate over 28 days. The reason for this behavior is not determined, however possible causes are discussed and further studies are recommended.
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Hive : Produktutveckling av en additivt tillverkad sänglampa

Nilsson, Jens January 2023 (has links)
Normada arbetar med att utveckla additivt tillverkade (3D-printade) möbler i skandinavisk stil och vill nuutöka sin produktportfölj med mindre produkter, såsom en sänglampa. Denna rapport fokuserar på att lösa ettvanligt problem med sänglampor idag, nämligen att de oftast antingen ger riktat ljus lämpligt för läsning ellerspritt ljus som skapar en mysig atmosfär. Det innebär att de sänglampor som människor har hemma antingeninte kan erbjuda en mysig spridd ljusstämning eller att det är svårt att läsa i det utstrålande ljuset. Detta projekthar hotell som målgrupp.Detta projekt syftar till att lösa detta problem genom en designprocess som identifierar dagensanvändarcentrerade utmaningar för att sedan lösa dem under processens gång. Målet är att utveckla en fulltfungerande produkt som är så nära produktionsklar som möjligt. Detta projekt utförs under vårterminen 2023på Luleå tekniska universitetet och är ett examensarbete på kandidatnivå som en del av utbildningen tekniskdesign.Projektet resultera i en sänglampa i skandinavisk stil som är fullt fungerande. Lampan kommer ha riktbarlampskärm med en avbländare som ger en mer spridd ljusupplevelse samtidigt som den tillgodoser möjlighetenatt kunna läsa i ljuset. Lampan har kvar optimeringsmöjligheter men är redo att produceras i små skalor. / Normada specializes in the development of additive manufactured (3D-printed) furniture in Scandinavian styleand aims to expand its product portfolio to include smaller items, such as a bedside lamp. This report focuseson addressing a common problem with bedside lamps today, namely that they typically either provide focusedlight suitable for reading or diffuse light that creates a cozy atmosphere. This means that the bedside lampspeople have at home either cannot offer a pleasant, diffuse lighting experience or it is challenging to read inthe emitted light. This project has hotels as the target group.This project aims to solve this problem through a design process that identifies current user-centered challengesand addresses them throughout the process. The goal is to develop a fully functional product that is as closeto production-ready as possible. The project is conducted during the spring semester of 2023 at LuleåUniversity of Technology as part of the bachelor's degree program in Industrial Design EngineeringThe project will result in a fully functional bedside lamp in Scandinavian style. The lamp will have adirectionally adjustable lampshade and a screen that provides a more even light distribution while fulfilling therequirements for reading. Although the lamp still has optimization possibilities, it is ready for production insmall scales.

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