Transition metal nitrides are a remarkable group of ceramic materials that offer exceptional properties such as high hardness, low tribological wear, excellent thermal stability, and high oxidation resistance. Alloys such as TiN, CrN, VN, ZrN, and HfN have been identified as ideal candidates for protective coatings on cutting tool inserts in the metal processing industry. While TiAlN has been widely accepted, ZrAlN and HfAlN alloys have much unexplored potential. With a melting point of HfN at 3300 °C, approximately 400 °C higher than TiN, HfAlN shows great potential for age-hardening at even higher temperatures. These remarkable materials inspire us to push the limits of what is possible, and to continue to innovate materials science. The work performed in this thesis focuses on the development of hard coatings using ionassisted reactive magnetron sputtering. The coatings are based on group IV TM-Al-N, where TM is either Ti, Zr, or Hf. The aim is to enhance the performance of these ceramic coatings by simultaneously increasing their hardness and toughness. To achieve this, the growth mechanisms, structure, and mechanical properties of the films were studied in detail. The coatings were deposited onto single crystal Si(001) and MgO(001) substrates. The first study describes the development of a multilayer structure, consisting of alternating layers of TiN and Zr0.37Al0.63N1.09, with a bilayer period of 20 nm, with the aim of combining the unique properties of the constituent materials. Cubic rocksalt TiN is known for its high hardness and unfortunate brittleness. Hexagonal wurtzite Zr0.37Al0.63N1.09 is less hard, but also more ductile. The crystal structure of the multilayers varied depending on the substrate temperature during growth. At temperatures below ~350 °C, the ZrAlN layers grew near amorphous, while they were nanocrystalline between 500 °C and 800°C. At 900 °C, the ZrAlN segregated into a nanolabyrinthine structure consisting of w-AlN and c-ZrN. The hardness of the films increased significantly with increasing deposition temperature, from 24 GPa to 36 GPa. The films also showed superior fracture stress compared to the available literature, increasing from 6.1 to 7.7 GPa. The fracture toughness of the films was also improved compared to the binary constituents, up to 2.8 MPa√m. These findings illustrate the potential of combining diverse materials, to create new structures with enhanced properties and highlight the importance of optimizing the growth conditions to achieve the desired film functionality. In a second study, single-crystal Hf1-xAlxNy films were grown at high temperatures on MgO(001) substrates. Excess nitrogen in HfNy (y=1.22, 1.33) film created ordered nanosized domains of variations in the nitrogen composition, leading to the formation of a compositionally modulated superstructure. In Hf0.93Al0.07N1.15, the immiscibility of the constituents (c-HfN and c-AlN) causes the formation of a superstructure consisting of isostructural Al-rich and Hf-rich domains due to surface initiated spinodal decomposition. Micropillar compression tests reveal a ductile HfN1.22 and substantial strain hardening upon deformation. Hf0.93Al0.07N1.15 exhibited a brittle nature, although at a substantially increased yield stress in comparison, consistent with the improved hardness from 26 GPa to 40.5 GPa, measured by nanoindentation. / <p>Funding agencies: The Swedish Research Council, VR (grant no. 2018-05190), the Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971), and the center in Nano Science and Technology, CeNano.</p>

This study examines the efficiency of punching compared to laser cutting in sheets of Ultra High Strength Steel (UHSS). The study was conducted to determine which process is more efficient with respect to sheet thickness, where the quality of the cut edge is also taken into consideration of whether punching is recommended over laser cutting. The need for information surrounding punching in UHSS will grow as UHSS becomes more common. A simple screener, with dimensions of 1x1 m, with 169 holes, Ø=15 mm, was the sample shape used to test and compare punching to laser cutting. Simulations were made of punching two sheets of Hardox® 500 Tuf with a thickness of 4 mm respectively 5 mm. The laser cutting was also simulated, were a sheet thickness of 4,5,6 and 8 mm was tested, were both a 6 kW laser and a 10 kW laser were used. The lasers use O2  as its high-pressure gas. The punching time was calculated using parameters used for material properties in between S355 and a stainless steel, as it was thought that the punching speed more or less stays the same with varying materials. The cutting time for laser is barely affected by alloying elements and so the cutting time for Hardox® 500 Tuf is estimated to be that of the cutting time of S355. The simulations of punching, laser cutting, and the schematic of the sample screener was done by the company Weland AB. No physical punching was done due to a lack of proper tooling. The simulations of both punching and laser cutting resulted in punching being seven to eight times faster than laser cutting. But due to the extreme properties of Hardox® 500 Tuf, the cut edge of the punched sheets are speculated to be inferior and not suitable for typical wear plate applications. It istherefore recommended to laser cut Hardox 500® Tuf, until further research is done. / Denna studie undersöker effektiviteten av stansning jämfört med laserskärning i plåt av Ultra High Strength Steel (UHSS). Studien genomfördes för att bestämma vilken process som är effektivare med avseende på plåttjocklek, där kvaliteten på den skurna kanten också tas i beaktning vare sig stansning rekommenderas över laserskärning. Behovet av information kring stansning i UHSS kommer att öka i och med att UHSS blir vanligare. En enkel sikt, med måtten 1x1 m, med 169 hål, Ø = 15 mm, var utformningen av plåten som användes för att testa och jämföra stansning med laserskärning. Simuleringar av att stansa två plåtar av Hardox® 500 Tuf gjordes, med en tjocklek av 4 mm respektive 5 mm. Laserskärningen simulerades också, där en plåttjocklek på 4,5,6 och 8 mm testades, där både en 6 kW laser och en 10 kW laser simulerades. Lasrarna använder O2  som högtrycksgas. Stanstiden beräknades med hjälp av parametrar som används för material med materialegenskaper mellan S355 och rostfritt stål, eftersom man ansåg att stansningshastigheten mer eller mindre förblir densamma för olika material. Skärtiden för laser påverkas knappt av legeringsämnen och därför beräknas skärtiden för Hardox® 500 Tuf vara samma som skärtiden för S355. Simuleringarna av stansning och laserskärning samt ritningen för provets utformning, gjordes av företaget Weland AB. Ingen fysisk stansning gjordes på grund av brist på rätt verktyg. Simuleringarna av både stansning och laserskärning resulterade i att stansning var sju till åtta gånger snabbare än laserskärning. Men på grund av de extrema egenskaperna hos Hardox® 500 Tuf, spekuleras det att kvaliteten på den skurna kanten hos de stansade plåtarna vara undermålig, och lämpar sig då ej för typiska slitplåtstillämpningar. Det rekommenderas därför att laserskära Hardox 500® Tuf tills ytterligare forskning har utförts.

Welding aluminium often results in porosity in the weld. One way to reduce porosity is by carful weld preparation and cleaning. In this master thesis report laser ablation was done on aluminium plates before welding to remove dirt and the surface oxide layer. Different hold times from finish of laser ablation to start of welding was also used and evaluated. Cleaning with only ethanol or brushing and cleaning with ethanol was also used for comparison. In addition, two filler wires of the same material were used for the welding, one new unopened and one old that had been opened and kept in open packaging for two years. For one weld on laser ablated plates the old filler wire was also laser ablated before use. The results showed that new filler wire gave the least number of pores, and the results were nearly the same with laser ablated plates welded directly as with ethanol cleaned plates. Welds with old filler wire had a bigger range in the results and the cleaning methods of the plates had a bigger impact. The results from the welds with old filler wire showed less porosity in the welds on laser ablated plates with hold times of six minutes, one hour and one day compared to ethanol cleaned plates and brushed plates. In common for both filler wires were that the weld of the laser ablated plates with a hold time of a week had the most pores. The conclusions are that it is good to use the filler wire as close in time to the opening of the packaging as possible and not store it a long time to then use it later. Laser ablation is a valid option for cleaning, but the machine is expensive and therefore most suitable for weld preparation of welds in high demand applications or on plates with very much dirt or thick oxides. / Svetsning av aluminium resulterar ofta i porer i svetsgodset. Ett sätt att reducera porositeten är genom noggrann rengöring innan svetsning. I detta master exsamensarbete användes laserablation, eller laserblästring, av aluminiumplåt innan svetsning för att rengöra och ta bort ytoxiden. Olika väntetider från slutförande av laserablation till påbörjande av svetsning användes och utvärderades också. Förutom laserablation användes rengöring med endast etanol eller borstning och sedan rengöring med etanol som referens att jämföra med. Dessutom användes två tillsatstrådar i samma material med skillnaden att den ena var ny och oöppnad innan användning och den andra hade förvarats i en öppnad förpackning de senaste två åren. Till en av svetsarna på de laserablerade plåtarna användes en gammal tillsatstråd som hade laserablerats. Resultatet visade att den nya tillsatstråden gav minst antal porer i den färdiga svetsen, oberoende av vilken rengöringsmetod som hade använts. Svetsar gjorda med den gamla tillsatstråden hade större spridning i resultaten jämfört med den nya tråden och här spelade också rengöringsmetoden större roll. Resultaten från svetsar gjorda med den gamla tillsatstråden hade färre porer i svetsarna på de laserablerade plåtarna med väntetiderna sex minuter, en timme och ett dygn jämfört med de som var rengjorda med etanol och de som var borstade. Gemensamt för bägge trådarnas svetsar var att de svetsar som var gjorda på laserablerade plåtar med väntetid på en vecka hade flest antal porer. Slutsatserna är att det är bra att använda tillsatstråden så nära som möjligt från när den öppnades, och inte att förvara den under lång tid för att senare användas igen. Laserablation är ett bra alternativ till rengöring, men laserableringsmaskiner är dyra. Därför passar laserablering bäst för rengöring innan svetsning när det ställs höga krav på svetsen och slutprodukten. Laserablering kan också vara användbart om det är väldigt smutsiga plåtar eller om ytoxiden är tjock.

This research work proposes a new methodology for implementing Value Stream Mapping, in processes that feature a High-Mix, Low-Volume product base.   The opportunity for adapting the methodology singularly for these types of environments was identified because implementing Value Stream Mapping as proposed in Learning to See features several drawbacks when implemented in High-Mix, Low-Volume.  Although Value Stream Mapping has been proven to enhance many types of processes, its advantages are shrunk if they are implemented in High-Mix, Low-Volume processes.   High-Mix, Low-Volume processes are types of processes in which a high variety of finished goods are produced in relatively low amounts.  The high variety of finished goods causes several complications for the implementation of flow.  The difficulties that prevent the flow are the following: The variance in the products: With hundreds, or sometimes thousands of possible finished goods, the number of products causes a non-repetitive process. The variance in the routings:  All of the products that are produced can have completely different process routings, or order of stations it has to visit.  This makes the application of production lines quite difficult. The variance in the cycle times for each process.  Each of the different products can have completely different capacity requirements at a specific machine, which limits the predictability of the process.   This purpose of the thesis is to gather the best practices for controlling and improving High-Mix, Low-Volume processes and merge them with some innovative ideas to create an inclusive Value Stream Mapping methodology which is better fitted with the types of complications in High-Mix, Low-Volume environments.  In parallel, the methodology is tested with the company: Boston Scientific, in their Ureteral Stents manufacturing process.   The real-life experimentation will allow for the fine-tuning of the methodology, in order to truly create impact in the process.

Wissenschaftliche Schriftenreihe, die Dissertationen der Professur Schweißtechnik beinhaltet.

A welding procedure specification is the document describing how a weld joint should be constructed. Arc weld processes are characterized by transient thermal behavior, leading to rapid changes in material properties and dynamic interaction between weld and base material. The objective of the project is to explore how the use of an improved CWM-platform affects representative stress and strain fields in order to assess welding procedure qualification records. Forthis project, the accumulated thermal and mechanical influences from the first run to the final run are brought forward, in one and the same meshed geometrical model. Both the thermal and mechanical material model of the platform are designed to be used for modelling of the base- and weld material,promoting the simulation of the intricate combination of the thermal, elastic,and plastic strains on the plastic strain hardening and the formation of residual stress fields. The output of the simulation is mainly weld cooling times, residual stresses, and deformations. This analysis is taken further by examining how residual stresses influence crack driving force under elastic and plastic loading. In addition, the output from the simulations can be used to assess the realism of the proposed welding parameters. The main experimental welding procedure examined comes from the IIW RSDP Round Robin Phase II benchmark project, where the main aim was to benchmark residual stress simulations. This work was found to contain many applicable challenges of a CWM-analysis project.

Cutting forces and vibrations are essential parameters in the assessment of a cutting process. As the energy consumption in the machining process is directly affected by the magnitude of the cutting forces it is of vital importance to design cutting edges and select process conditions that will maintain high tool performance through reduced energy consumption. The vibrations are often the cause of poor results in terms of accuracy, low reliability due to sudden failures and bad environmental conditions caused by noise. The goal of this work is to find out how the cutting edge and cutting conditions affect the entry conditions of the machining operation. This is done utilizing experimental methods and appropriate theoretical approaches applied to the cutting forces and vibrations. The research was carried out through three main studies beginning with a force build-up analysis of the cutting edge entry into the workpiece in intermittent turning. This was followed by a second study, concentrated on modelling of the entry phase which has been explored through experiments and theory developed in the first study. The third part was focused on the influence of the radial depth of cut upon the entry of cutting edge into the workpiece in a face milling application. The methodology for the identification of unfavourable cutting conditions is also explained herein. Important insights into the force build-up process help addressing the correlation between the cutting geometries and the rise time of the cutting force. The influence of the nose radius for a given cutting tool and workpiece configuration during the initial entry is revealed. The critical angle i.e. the position of the face milling cutter that results in unfavourable entry conditions has been explained emphasizing the importance of the selection of cutting conditions. Finally, the theoretical methods utilized for the evaluation of the role of cutting edge geometry within entry phase dynamics has been explored. This has revealed the trends that are of interest for selection of cutting conditions and cutting edge design.

Vid pulverbågssvetsning med växelströms inställning kan man ändra växelströmmens våg så att den är på den negativa strömsidan större delen av tiden. Det man inte vet när vågformen ändras är vilken påverkan det har på materialets mekaniska egenskaper. Påverkan på materialets mekaniska egenskaper testades genom att ett prov svetsades som referens med likström och tre prov svetsades med växelström med olika vågformer. Testerna som tas på de svetsade provbitarna är slag- och dragprov samt hårdhetsprovning och frametsnig av macroprov för verifiering av svetsfogen. Tre serier med fem slagprov samt två dragprov tas ut och testas på varje bit. Det som resultaten visar är att den värmepåverkade zonen (SAW) inte har påverkats av de olika vågformer, offset och balans utan att slagsegheten och den statiska hållfastheten varit samma som de resultat som referensproven har haft.

Anforderungen an Verbindungen, Verbindungstechnik, Fügen, Modellierungspraxis, Beispiel Verschraubung, Beispiel Klebverbindung, Beispiel Schweißung, Thesen zu Simulationen in der Verbindungstechnik

Schriftenreihe, die Tagungsbände und Beiträge der Professuren Fügetechnik und Montagetechnik beinhaltet.