In the production of glass, the addition of more cullet to the batch of glass and the reduction of the thickness of glass are means to reduce energy consumption and raw material usage. This contributes towards improved energy efficiency targets of the European Union. This thesis investigated the energy consumed for the process of strengthening thinner glass as well the environmental implications of thinner and stronger compared to conventional glass across the life cycle of glass. The life cycle phases also included a recycling phase where 70% of the used glass was recycled with the remaining 30% being landfilled. The functional unit selected for this study was 1m2 of SLS glass, 4mm thick, with an average light transmittance of 91%. This corresponds to 10kg of clear float glass as per general rule. The findings of this thesis showed that one of the major contributing factors to high energy consumption in the melting phase of SLS glass is low efficiency of the furnace; this led to significant energy losses in the production of SLS glass. Recycling of flat glass, at a 70% rate, led to a 12% reduction in total global warming potential, a 10% reduction in the Acidification Potential, a 13% reduction in the Eutrophication Potential in marine environs, and a 7% reduction in the Eutrophication Potential in terrestrial habitats. The chemical and thermal strengthening process consumed 2.24 and 2.37 kWh/m2 respectively. The consequential impact of this is dependent on the source of the electricity for the strengthening processes. It was concluded that the energy used for the strengthening of the thinner glass is considerably less than the energy used in the production of a conventional glass that satisfies the same strength parameters.

Manufacturing of aero engine components requires attention to residual stress and final shape of the product in order to meet high quality product standards.This sets very high demands on involved manufacturing steps to meet design requirements. Simulation of manufacturing processes can therefore be animportant tool to contribute to quality assurance.The focus in this work is on simulation of a manufacturing process chain comprising of sheet metal forming, welding and a stress relief heat treatment.Simulation of sheet metal forming can be used to design a forming tool design that accounts for the material behaviour, e.g. spring back, and avoid problems such as wrinkling, thinning and cracking. Moreover, the simulation can also show how the material is stretched and work hardened. The residual stresses after forming may be of local character or global depending on the shape that is formed. However, the heat affected zone due to welding is located near the weld.The weld also causes large residual stresses with the major component along the weld. It is found that the magnitude of the residual stresses after welding is affected by remaining stresses from the previous sheet metal forming. The final stress relieve treatment will relax these residual stresses caused by e.g. forming and welding. However, this causes additional deformations.The main focus of this study is on how a manufacturing process step affects the subsequent step when manufacturing a component of the nickel-based super alloy 718. The chosen route and geometry is a simplified leading edge of an exhaust case guide vane. The simulations were validated versus experiments. The computed deformations were compared with measurements after each manufacturing step. The overall agreement between experiments and measurement was good. However, not sufficiently accurate considering the required tolerance of the component. It was found from simulations that the residual stresses after each process affects the subsequent step. After a complete manufacturing process chain which ends with a stress relief heat treatment the residual stresses were not negligible. VIII Special experiments were performed for studying the stress relief in order to understand how the stresses evolve through the heat treatment cycle during relaxation. It was found that the stresses were reduced already during the beginning of the heating up sequence due to decreasing Young´s modulus and yield stress with increasing temperature. Relaxation due to creep starts when a certain temperature was reached which gave a permanent stress relief.

The purpose of this study was to generate a greater understanding of how the shunt distance affects the shunting phenomena which occurs when working with resistance spot welding (RSW). Shunting affects the quality of the weld and the goal of the study was to create guidelines for RSW to minimize its impact on the weld quality. In order to minimize waste from production and to reduce the welding time there is need for understanding of what the shunt effect depends on. To evaluate what impact the shunt distance will have on the weld, two different experiments were performed. In the first experiment, a one-dimensional welding lobe was manufactured for various materials and the current range was compared over three different shunt distances. The second experiment consisted of welding with a constant current on different shunt distances to investigate how this would impact the second weld performed in the welding sequence. A range of different steel grades and sheet thicknesses was used in the experiments to further explore what impact different material properties will have on the shunt effect. The result showed that the shunt distance has little impact on the acceptable weld-current range, with minor deviations. However, the shunt distance will affect the size of the shunted weld, which decreases as the shunt distance is reduced. Overall, the data collected in this study is not expansive enough to make guidelines that could be implemented in today´s industry. The phenomena of shunting require more data to fully be understood. / Syftet med denna studie var att skapa en större förståelse för hur shuntavståndet påverkar det shunt-fenomen som uppstår när man arbetar med punktsvetsning (RSW). Shuntning påverkar svetsens kvalitet och målet var att skapa riktlinjer för arbete med RSW för att minimera shunt-effektens påverkan på svetsen. I syfte att kunna minimera spill i produktionen samt att minska svetstiden krävs det förståelse av vad shunt effekten beror på. För att utvärdera vilken påverkan shuntavståndet kommer att ha på svetsen utfördes två olika experiment. I det första experimentet skapades en endimensionell svetslob för varje material och det genererade strömintervallet jämfördes över tre olika shuntavstånd. Det andra experimentet bestod av svetsning med en lika stor ström vid olika shuntavstånd för att undersöka hur detta skulle påverka den andra svetsen. En rad olika stålsorter och plåttjocklekar användes för att ytterligare se vilken påverkan dessa faktorer kom att ha på shunteffekten. Resultatet visade att shuntavståndet hade liten inverkan på det acceptabla svetsströmintervallet, med mindre avvikelser. Emellertid påverkar shuntavståndet storleken på den shuntade svetsen genom att storleken minskar när shuntavståndet minskas. Sammantaget räcker inte de uppgifter som samlats in i denna studie för att skapa riktlinjer som skulle kunna implementeras i dagens industri, utan det krävs mer data för att fullständigt kartlägga shunteffekten.

Additive manufacturing has the power to redefine how we create components. In order to minimize removal of printed material, deformation must be kept a minimum. When deposition rate is increased during directed energy deposition so is the power requirement for melting the feedstock. This increases the residual stresses in the material and leads to more deformation. The deposition rate must be increased without introducing large deformation, if additive manufacturing is ever to be economical in many engineering fields. This study aims to explore if pulsing the laser can decrease deformation using a design of experiments approach. Other types of defects and microstructural changes are also evaluated. A total of 17 sets of parameters were used varying laser power, pulse frequency and the time fraction when the laser was powered on. The amount of powder added to a substrate was constant and the build geometry as similar as possible for all tests. Ultimately no conclusion could be drawn regarding pulsing parameters effect on deformation. It was found pulsing the laser lowered the powder efficiency drastically, which may have had a bigger effect on the experimental set up than anticipated. In a similar manner, no relation between pulsing parameters, defects and microstructure could be observed. / Additiv tillverkning ger oss möjligheten att tillverka komponenter på ett sätt som tidigare inte har varit möjligt. För att minimera efterföljande svarvning och fräsning av additivt tillverkade delar måste deformationen kontrolleras. När deponeringshastigheten ökar måste även sträckenergin ökas i direktenergideponeringsprocesser. Detta leder till höjda restspänningsnivåer i materialet och medför en större efterföljande deformation. Om additiv tillverkning i framtiden ska ha en chans att mäta sig ekonomiskt med konventionella metoder måste deponeringshastigheten öka för många applikationsområden. Denna studie använder Design of Experiments för att undersöka om en pulserande laser kan utnyttjas för att minska deformationen när metallpulver används som tillsats. Även andra typer av defekter och förändringar i mikrostruktur har utvärderats. Totalt undersöktes 17 olika parameteruppsättningar med varierande lasereffekt, pulsfrekvens och aktiv lasertid. Pulverdeponeringshastigheten hölls konstant mellan försöken och byggeometrierna var så lika som möjligt för alla tester. I slutändan kunde ingen slutsats dras när det gäller hur pulserande parametrar påverkar deformationen. Det visade sig att en pulserande parameter sänker pulvereffektiviteten drastiskt, vilket kan ha haft en större effekt på experimentets uppsättning än förutspått. På liknande sätt kunde inget säkert samband mellan pulserande parametrar, defekter och mikrostruktur observeras.

Tungsten carbide (WC) based metallic matrix coatings sprayed using high velocity air fuel (HVAF) technique have attracted increasing attention as they show excellent tribological performance in various wear conditions. In the HVAF method, particles’ in-flight temperature and velocity can be influenced by the process variables including nozzle configuration as well as feedstock particle size range. On the other hand, the chemistry of metallic binder can also play a key role in determining both properties and performance of these coatings. In this thesis, characteristics and tribological behaviour of HVAF-sprayed WC-based coatings were investigated employing four different nozzle configurations (4L2, 4L4, 5L2and 5L4), and three different feedstock particle sizes of WC-CoCr feedstock powder (5/20, 5/30 and 15/45 μm). Also, characteristics and performance of coatings processed with four different WC-based feedstocks comprising alternative binders to traditionally used CoCr (namely CoCr, NiMoCrFeCo,FeNiCrMoCu and FeCrAl) were investigated. Characteristics of the coatings were explored by conducting scanning electron microscopy observations, microindentation testing and X-ray diffraction analysis. Performance of the coatings was evaluated by conducting sliding wear, dry jet erosion wear and sand rubber wheel abrasion wear testing. Moreover, material removal mechanisms in the coatings subjected to the above tests were investigated through post wear analysis. X-ray diffraction analysis showed that no considerable phase change compared to the starting feedstock was observed in any of the coatings sprayed by HVAF technique. It was revealed that decrease in powder particle size range can result in an improvement in microstructural characteristics, such as homogeneity and density, as well as hardness of the coatings. Besides, it can lead to a substantial improvement in wear performance of the coatings. It was shown that using various nozzle configurations does not result in any considerable change in characteristics or performance of the HVAF-sprayed WC-CoCr coatings. It was further shown that, by decreasing particle sizes from coarse to medium or fine, a significant difference can be observed. While wear mechanisms for medium and fine feedstock coatings were dominated by ploughing and fracture of individual carbide grains, for the coarse feedstock coatings ploughing and grooving along with the local removal of coating material were observed. Hardness values for all the four coatings with different binder chemistries were in a narrow range of 1100 – 1300 HV0.3. WC-NiMoCrFeCo and WC-FeNiCrMoCu coatings showed better or comparable sliding wear performance compared to WC-CoCr coating (as reference). WC-FeNiCrMoCu and WC-FeCrAl coatings showed comparable performance under erosion conditions while all the three binder alternatives yielded slightly inferior coating performance under abrasion wear, compared to the reference coating. While ploughing was the common wear mechanism in all the four coatings, pitting was noted in coatings with CoCr and FeNiCrMoCu binders in case of sliding wear. / Populärvetenskaplig Sammanfattning Cermet-beläggningar består av WC-partiklar inbäddade i ett metallbindemedel,sprutat med High Velocity Air Fuel (HVAF) uppvisar utmärkt tribologiskprestanda under olika slitage förhållanden. Med HVAF-tekniken kan partiklarnasflygtemperatur och hastighet påverkas av konfigurationen av den utrustning somanvänds såväl som partikelstorleksintervallet för råmaterialet. Därtill kan kemin hos det metalliska bindemedlet spela en nyckelroll för beläggningarnas egenskaper och prestanda. I denna avhandling undersöktes egenskaper och tribologiskt beteende hos HVAF-besprutade WC-baserade beläggningar. Undersökningen gjordes genom att använda fyra olika uppsättningar av ändra sprutparametrar förHVAF-processen där fyra olika munstyckskonfigurationer (4L2, 4L4, 5L2 och5L4) och tre olika partikelstorleksintervaller av WC-CoCr råvarupulver (5/20,5/30 och 15/45 μm). Studieegenskaper och prestanda för alla deponerade beläggningar, påverkan av processvariabler (olika munstyckskonfigurationer och olika partikelstorlekar) undersöktes. Dessutom undersöktes egenskaper och prestanda för tre olika WC-baserade råvaror med alternativa bindemedel till CoCr (NiMoCrFeCo, FeNiCrMoCu och FeCrAl) och jämfördes med WC-CoCrbeläggningsom referens. Beläggningens egenskaper undersöktes genom att genomföra SEM-analys, mikroindragningstest och röntgenanalys. Beläggningens prestanda utvärderades genom att utföra glidförslitning, erosionsslitage under torra förhållanden och test med torr sand/gummihjulanordning. Vidare undersöktes mekanismer för materialavlägsning i beläggningarna med ovanstående tester genom analys efter slitage. Ingen avsevärd fasförändring observerades för alla beläggningar som besprutades med HVAF-teknik. Det avslöjades att minskning av pulvrets genomsnittliga partikelstorlek resulterade i en förbättring av mikrostrukturella egenskaper, såsom homogenitet och densitet, samt beläggningarnas hårdhetsvärde. Dessutom leder det till en avsevärd förbättring av beläggningens slitageförmåga. Det visades att användning av olika munstycken till HVAF-processen inte resulterar i en avsevärd förändring i egenskaper eller prestanda hos WC-CoCr-beläggningarna. När det gäller förslitningsmekanismer visades det att genom att minska partikelstorleken från grov till medium eller fin sågs en avsevärd skillnad. För beläggningar besprutade med fina och medelstora partiklar dominerades förslitningsmekanismer av plöjningsslitage och sprickor av enskilda hårdmetallkorn. För grova beläggningar observerades plöjningsslitage och spårning tillsammans med avlägsnande av material. Ingen signifikant skillnad i mikrostruktur eller fasförändring observerades i alla beläggningar med alternativa bindemedel såväl som WC-CoCr som referensbeläggning. Hårdhetsvärdet för alla de fyra beläggningarna låg inom x intervallet 1100 - 1300 HV0.3. NiMoCrFeCo och FeNiCrMoCu visade bättre eller jämförbar glidförmåga med referensbeläggningen. FeNiCrMoCu och FeCrAl visade jämförbara prestanda under erosionsförhållanden och alla de tre undersökta beläggningsmaterialen visade något sämre prestanda under nötningsslitage jämfört med referensbeläggningen. Medan plöjningsslitage var den vanliga förslitningsmekanismen i alla de fyra beläggningarna noterades gropning i beläggningarna CoCr och FeNiCrMoCu vid glidförslitning.

Stress corrosion, SC, in some cases gives rise to stress corrosion cracking, SCC, which differs from purely stress intensity driven cracks in many aspects. They initiate and grow under the influence of an aggressive environment in a stressed substrate. They grow at low load and may branch. The phenomenon of SCC is very complex, both the initiation phase and crack extension itself of SCC is seemingly associated with arbitrariness due to the many unknown factors controlling the process. Such factors could be concentration of species in the environment, stress, stress concentration, electrical conditions, mass transport, and so on.In the present thesis, chemically assisted crack initiation and growth is studied with special focus on the initiation and branching of cracks. Polycarbonate plates are used as substrates subjected to an acetone environment. Experimental procedures for examining initiation and branching in polycarbonate are presented. An optical microscope is employed to study the substrate.The attack at initiation is quantified from pits found on the surface, and pits that act as origin for cracks is identified and the distribution is analysed. A growth criterion for surface cracks is formulated from the observations, and it is used to numerically simulate crack growth. The cracks are seen to coalesce, and this phenomenon is studied in detail. Branching sites of cracks growing in the bulk of polycarbonate are inspected at the sample surface. It is found that the total width of the crack branches are approximately the same as the width of the original crack. Also, angles of the branches are studied. Further, for comparison the crack growth in the bulk is simulated using a moving boundary problem based algorithm and similar behaviour of crack branching is found. / <p>Both papers in thesis as manuscript, paper II with title "Branching cracks in a layered material - Dissolution driven crack growth in polycarbonate"</p>

Additive Manufacturing (AM), commonly known as 3D printing, represents manufacturing technology that creates objects layer by layer based on 3D model data. AM technologies have capabilities that provide engineers with new design opportunities outside the constraints of traditional subtractive manufacturing. These capabilities of AM have made it attractive for manufacturing components in the space industry., where parts are often bespoke and complex. In particular, Laser Powder Bed Fusion (LPBF) has attracted attention due to its ability to produce components with the part properties required for space applications. Additionally, the precision of the laser enables the production of innovative near-net shape and low-weight part designs.  However, due to the powdered metal material, the LPBF process is categorised with rough surfaces in the as-built state. The extent and effect of surface roughness are closely linked to geometrical design variables, including build orientation, overhangs, support structure, and build parameters; hence the more intricate the design, the more difficult the removal of this roughness. Consequently, the as-built surface for most applications is too rough and could adversely affect proprieties, i.e., fatigue. Hence, practical Design for AM (DfAM) supports should be developed that understand how design factors, such as surface roughness, will impact a part’s performance. This thesis therefore presents literature reviews on research related to LPBF surface roughness and design support, exploring the trends in managing surface roughness and investigations on the characteristics of design support. Additionally, through a space industry case study, a proposed process involving additive manufacturing design artefacts (AMDAs) is considered to investigate and describe the relationship between design, surface roughness, and performance. The review found that, in general, research focuses on the relationship between surface roughness and LPBF build parameters, material properties, or post-processing. There is very little support for design engineers to consider how surface roughness from an AM process affects the final product (less than 1% of the review articles). In investigating surface roughness, the AMDA process identified characteristics that impact roughness levels and geometric adherence to part design. Additionally, twelve characteristics of design support were identified and considered to review the AMDA process. The process aided the evaluation of design uncertainties and provided indications of part performance. However, iterations of the process can be required to clarify product-specific design uncertainties. Though, the designer obtains a better understanding of their design and the AM process with each iteration. The inclusion of the requirement to set evaluation criteria for artefacts was recommended to develop the AMDA process as design support.

Nickel-based superalloys and tool steels are well-known high-performance alloys due to their extensive use in many different industries. Nickel-based superalloys have found their way into aircraft, aerospace, marine, chemical, and petrochemical industries owing to their excellent high-temperature corrosion and oxidation resistance. On the other hand, tool steels could provide a combination of outstanding corrosion and wear resistance. They can play an important role in cutting and wear applications and manufacturing plastic extrusion and food processing components. Near-net shape manufacturing using powder metallurgy (PM) and hot isostatic pressing (HIP) can serve as an efficient manufacturing process to produce these alloys. This technology can successfully tackle conventional manufacturing challenges of highly alloyed materials i.e. segregation during the casting process or cracks during hot working processes of Ni-based superalloys, and carbide segregation and formation of large and irregularly shaped carbides in wrought and hot rolled tool steels. However, the presence of precipitates on prior particle boundaries (PPBs) in Ni-based superalloys, and metallurgical defects like non-metallic inclusions in both Ni-based superalloys and tool steels may affect the fatigue performance of these PM-HIPed products. This licentiate thesis aims to investigate the microstructure and fatigue behavior of two PM-HIPed alloys i.e. Inconel 625 and high-nitrogen tool steel. The results confirm precipitation along PPBs in PM-HIPed Inconel 625; however, no effect was detected in the fractography studies of the high cycle fatigue samples, and tensile properties were comparable with wrought materials reported in the literature. On the other hand, the microstructure of PM-HIPed high-nitrogen tool steel displayed dispersed precipitates and no traces of PPBs. Moreover, in both cases, i.e. very high cycle fatigue of PM-HIPed high-nitrogen tool steel and high cycle fatigue of PM-HIPed Inconel 625, fatigue crack initiation was attributed to the presence of non-metallic inclusions, either individually or agglomerated with precipitates. This underscores the significance of the manufacturing process in fatigue performance. / Near-net shape manufacturing using powder metallurgy (PM) and hot isostatic pressing (HIP) can serve as an efficient manufacturing process to produce high-performance alloys. Among the variety of engineering alloys, Nickel-based superalloys and tool steels stand out as well-known high-performance alloys, widely employed across diverse industries. PM-HIP technology can successfully address conventional manufacturing challenges associated with highly alloyed materials, such as segregation during the casting process or cracks during hot working processes of Ni-based superalloys, and carbide segregation and the formation of large and irregularly shaped carbides in wrought and hot rolled tool steels. However, the presence of precipitates on prior particle boundaries in Ni-based superalloys, and metallurgical defects like non-metallic inclusions in both alloys, may affect the fatigue performance of these PM-HIPed products. The present study aims to assess two PM-HIPed alloys, namely Inconel 625 and high-nitrogen tool steel, with a comprehensive examination of their microstructure and fatigue properties. The objectives include examining the microstructural features introduced by the PM-HIP process and understanding how they influence fatigue failure mechanisms in these alloys.

In this work, Slow Strain Rate Test (SSRT) testing, Light Optical Microscopy (LOM) and Scanning Electron Microscopy (SEM) were used to study the effect of microstructure, corrosive environments and cathodic polarisation on stress corrosion cracking (SCC) of two grades of high strength steels, Type A and Type B. Type A is manufactured by quench and tempered (Q&amp;T) method. Type B, a normalize steel was used as reference. This study also supports electrochemical polarisation resistance method as an effective testing technique for measuring the uniform corrosion rate. SSRT samples were chosen from base metal, weld metal and Heat Affected Zone (HAZ). SSRT tests were performed at room temperature under Open Circuit Potential (OCP) and cathodic polarisation using 4 mA/cm2 in 1 wt% and 3.5 wt% NaCl solutions. From the obtained corrosion rate measurements performed in 1 wt% and 3.5 wt% NaCl solutions it was observed that increased chloride concentration and dissolved oxygen content enhanced the uniform corrosion for all tested materials. Moreover, the obtained results from SSRT tests demonstrate that both Q&amp;T and normalized steels were not susceptible to SCC in certain strain rate (1×10-6 s-1) in 1 wt% and 3.5 wt% NaCl solutions under OCP condition. It was confirmed by a ductile fracture mode and high reduction in area. The weld metal of Type A with acicular ferrite (AF), pro-eutectoid (PF) and bainite microstructure showed higher susceptibility to hydrogen assisted stress corrosion cracking compared to base metal and HAZ. In addition, typical brittle intergranular cracking with small reduction in area was observed on the fracture surface of the Type A due to hydrogen charging.

Additive manufacturing (AM) has experienced significant growth and development in recent years, owing to the ability to produce complex parts using a wide range of materials with relative ease. Powder bed-based metal AM has been at the forefront of this growth, even reaching the point where parts can be manufactured for end-use applications. Binder jetting (BJ) is one such technique where a liquid binder is selectively deposited on powder layers to create a green body which is then densified using sintering. The aim of this work was to use binder jetting to produce parts using Vanadis 4 Extra, a highly alloyed cold-work tool steel produced by Uddeholm AB for applications involving high demand on abrasive wear. Optimization of the densification parameters, which included debinding atmosphere, debinding temperature, sintering atmosphere, sintering temperature, and sintering time, to achieve full density parts was carried out as the first phase. It was found that the sintering atmosphere and time had the most significant impact on the density of the samples while the debinding atmosphere heavily impacted the C residue from the binder. In the second phase, samples were produced using the optimized parameters for mechanical analysis, which included analyses of the surface roughness and the wear resistance of the binder jetted samples against the conventionally produced samples. The surface roughness was in line with the data presented in literature for binder jetted samples. The binder jetted samples produced during this work exhibited better wear resistance than the conventionally produced samples, with the samples post-processed using hot isostatic pressing showing even better wear resistance. One possible explanation is the diffusion of N from the sintering atmosphere into the samples, leading to the conversion of carbides to carbonitrides and even nitrides. However, further investigation is needed in order to confirm this theory.