This diploma thesis deals with development and design modifications of tire mould segment which will be batch produced by additive technology Selective Laser Melting. Material for its production is maraging steel 1.2709. Lattice structure was used inside the segment construction. The geometry of the lattice cell was chose based on two main factors – eliminating production costs and providing sufficient stiffness. Strength of the segment was calculated by FEM. The functional sample was made and its distortion was analyzed by optical digitalization.

The diploma thesis deals with the study of the influence of process parameters of AlSi7Mg0.6 aluminum alloy processing using the additive technology Selective Laser Melting. The main objective is to clarify the influence of the individual process parameters on the resulting porosity of the material and its mechanical properties. The thesis deals with the current state of aluminum alloy processing in this way. The actual material research of the work is carried out in successive experiments from the welding test to the volume test with subsequent verification of the mechanical properties of the material. Material evaluation in the whole work is material porosity, stability of individual welds, hardness of the material and its mechanical properties. The results are compared with the literature.

The master's diploma thesis deals with the mechanical and structural characteristics of aluminium-base alloy 2000 series, produced by selective laser melting (SLM). The experimental part of the thesis deal with selection of SLM processing parameters, influence of scanning strategy and evaluation of mechanical and structural characteristics of fabricated materials. Mechanical characteristics were evaluated based on results of tensile tests and microhardness measurement. Structural characteristics of materials produced by SLM were evaluated using metallographic analysis.

Selective laser melting (SLM) is a powder-based additive manufacturing technique consisting of the exact reproduction of a three dimensional computer model (generally a computer-aided design CAD file or a computer tomography CT scan) through an additive layer-by-layer strategy. Because of the high degree of freedom offered by the additive manufacturing, parts having almost any possible geometry can be produced by SLM. More specifically, with this process it is possible to build parts with extremely complex shapes and geometries that would otherwise be difficult or impossible to produce using conventional subtractive manufacturing processes. Another major advantage of SLM compared to conventional techniques is the fast cooling rate during the process. This permits the production of bulk materials with very fine microstructures and improved mechanical properties or even bulk metallic glasses. In addition, this technology gives the opportunity to produce ready-to-use parts with minimized need for post-processing (only surface polishing might be required). Recently, significant research activity has been focused on SLM processing of different metallic materials, including steels, Ti-, Ni- and Al-based alloys. However, most of the research is devoted to the parameters optimization or to feasibility studies on the production of complex structures with no detailed investigations of the structure-property correlation. Accordingly, this thesis focuses on the production and structure-property correlation of Al-12Si samples produced by SLM from gas atomized powders. The microstructure of the as-prepared SLM samples consists of supersaturated primary Al with an extremely fine cellular structure along with the residual free Si situated at the cellular boundaries. This microstructure leads to a remarkable mechanical behavior: the yield and tensile strengths of the SLM samples are respectively four and two times higher than their cast counterparts. However, the ductility is significantly reduced compared with the cast samples. The effect of annealing at different temperatures on the microstructure and resulting mechanical properties of the SLM parts has been systematically studied by analyzing the size, morphology and distribution of the phases. In addition, the mechanical properties of the SLM samples have been modeled using micro- structural features, such as the crystallite and matrix ligament sizes. The results demonstrate that the mechanical behavior of the Al-12Si SLM samples can be tuned within a wide range of strength and ductility through the use of the proper annealing treatment. The Al-Si alloys are generally used as pistons or cylinder liners in automotive applications. This requires good wear resistance and sufficient strength at the operating temperature, which ranges between 373 – 473 K. Accordingly, the tensile properties of the SLM samples were also tested at these temperatures. Changing the hatch style during SLM processing vary the texture in the material. Hence, samples with different hatch styles were produced and the effect of texture on their mechanical behavior was evaluated. The results show that the hatch style strongly influences both the mechanical properties and the texture of the samples; however no direct correlation was observed between texture and mechanical properties. The wear properties of the Al-12Si material was evaluated using pin-on-disc and fretting wear experiments. These experiments show that the as-prepared SLM samples exhibit better wear resistance than their cast counterparts and the SLM heat-treated samples. Finally, the corrosion investigations reveal that the SLM samples have similar corrosion behavior as the cast specimens under acidic conditions. A major drawback for the wide application of SLM as an industrial processing route is the limited size of the products. This is a direct consequence of the limited dimensions of the available building chambers, which allow for the production of samples with volumes of about 0.02 m3. A possible way to overcome this problem would be the use of the welding processes to join the small SLM objects to form parts with no dimensional limitations. In order to verify this possibility, friction welding was employed to join Al-12Si SLM parts. The results indicate that friction welding not only successfully permits the join materials manufactured by SLM, but also helps to significantly improve their ductility. This work clearly demonstrates that SLM can be successfully used for the production of Al-12Si parts with an overall superior performance of the mechanical and physical properties with respect to the conventional cast samples. Moreover, the mechanical properties of the SLM samples can be widely tuned in-situ by employing suitable hatch styles or ex-situ by the proper heat treatment. This might help the development of SLM for the production of innovative high-performance Al-based materials and structures with controlled properties for automotive and aerospace applications.

Das selektive Laserschmelzen (SLM) erlaubt komplexe Geometrien zu fertigen, die, z. B. in Form von integrierten Kühlkanälen, bei Werkzeugen von großer Bedeutung sind. Aktuell werden in der Industrie hauptsächlich Aluminium-, Stahl-, Titan-, Nickel- und Kobaltchromlegierungen mit SLM verarbeitet. Für die additive Fertigung sind Stähle interessant, die besondere Eigenschaften aufweisen. So wird für Konstruktionsbauteile größtenteils korrosionsbeständiger Stahl verwendet. Ein weiteres Anwendungsfeld ist die Herstellung von Werkzeugen. Die besonderen Ansprüche an die mechanischen Eigenschaften, die für Werkzeuge benötigt werden, erfüllen die Werkzeugstähle. Durch die Neigung zu Rissbildung und Verzug resultiert eine herausfordernde Verarbeitbarkeit im SLM-Prozess. Werkzeugstähle wurden bisher auf Grund dieser Herausforderungen selten mit SLM prozessiert. Es besteht daher ein großer Bedarf die Zusammenhänge zwischen dem Prozess, der Verarbeitbarkeit, dem entstehenden Gefüge und den resultierenden Eigenschaften aufzuklären. In dieser Arbeit werden die Mikrostruktur und die mechanischen Eigenschaften dreier hochfester Stahllegierungen, verarbeitet im SLM-Prozess, untersucht. Eine Legierungsentwicklung, speziell auf die Anforderungen des SLM-Prozesses zugeschnitten, ermöglicht, das volle Potenzial des SLM-Prozesses auszuschöpfen. Die Verarbeitbarkeit der neu entwickelten Legierung im SLM-Prozess konnte erfolgreich gegenüber den Ausgangslegierungen verbessert werden.

Additive Manufacturing, and specifically powder bed fusion processes, have advanced rapidly in recent years. Selective Laser Melting in particular has been adopted in a variety of industries from biomedical to aerospace because of its capability to produce complex components with numerous alloys, including stainless steels, nickel superalloys, and titanium alloys. Post-processing is required to treat or solve metallurgical issues such as porosity, residual stresses, and surface roughness. Because of the geometric complexity of SLM produced parts, the reduction of surface roughness with conventional processing has proven especially challenging. In this Thesis, two processes, abrasive flow machining and ultrasonic shot peening, are evaluated as surface finishing processes for selective laser melted 316L. Results of these experiments indicate that AFM can reliably polish as-built internal passages to 1 µm Ra or better but is unsuitable for passages with rapidly expanding or contracting cross-sections. AFM can also polish relatively small passages, but lattice components may prove too complex for effective processing. USP cannot achieve such low surface roughness, but it is a versatile process with multiple advantages. Exterior surfaces were consistently processed to 1.7 to 2.5 µm Ra. Interior surfaces experienced only partial processing and demonstrated high geometric dependence. USP significantly hardened the surface, but steel media hardened the surface better than ceramic media did. Both AFM and USP are recommended processes for the surface finishing of SLM manufactured parts. Good engineering judgement is necessary to determine when to use these processes and how to design for post-processing.

Selective laser melting (SLM), is a type of additive manufacturing, which selectively melts a pre-spread layer of metal powders and produce a part by a layer-on-layer manner. SLM has demonstrated a great potential to reduce size and weight in hydraulic manifolds. However, a theoretical base is lacking since friction loss is unclear in a SLMed fluid passage. In this study, various fluid passages without supports, from diameters from 4 mm to 16 mm, were produced horizontally using SLM. The profile was measured using a 3D scanner and surface roughness was measured using a confocal laser scanning microscope. Friction factor was studied using simulation, experiments, and classical theory. The hydraulic diameter of the SLMed passages is smaller than the design diameter. Surface roughness is extremely high on the top part of the inner wall while the rest part is around 10 μm. Such trends are irrelevant of passage diameters. Friction factors in SLMed passage is much larger than those predicted using Moody theory, particularly in laminar flow. The transition from laminar flow to turbulent flow appears at a smaller Reynolds number with increased passage diameter. The influence of the profile overweighs that of the surface roughness on friction factor.

Selective laser melting (SLM), one type of metal additive manufacturing (AM) technology, uses a highintensity laser to selectively melt pre-spread metal powders by a layer-on-layer manner. The technology does not only provide a new way of manufacturing but also innovates product design methodology. In this study, a hydraulic block manifold is designed and manufactured using SLM. In this paper, we present an AM-driven design approach of hydraulic manifolds based on a case study. The target is not only to reduce weight but also to enhance fluid flow by optimizing fluid path to reduce pressure drop. The novelty of the research includes developing a design approach of hydraulic manifolds using SLM with a particular focus on fluid flow. Compared to the traditional hydraulic manifold, the weight of the new SLMed hydraulic manifold was reduced by more than 80%, size by half. Pressure loss of the main functional oil circuit was reduced by 31%, illustrating that the new hydraulic manifold design simultaneously achieves lightweight and high performance. This study contributes to providing theoretical guidance to the design of additively manufactured hydraulic components with high performance.

Selective laser melting (SLM) is an additive manufacturing technology. In this thesis, a heat-treatable Al-3.5Cu-1.5Mg-1Si alloy and related materials (composites and hybrid materials) have been successfully fabricated by selective laser melting and characterized in terms of densification, microstructure, heat treatment, mechanical properties as well as tribological and corrosion behavior. Firstly, the fully dense SLM Al-Cu-Mg-Si alloy was fabricated by SLM successfully. The alloy shows a higher yield strength than SLM Al-12Si alloy, and lower wear resistance and corrosion rate than commercial 2024 alloy before and after T6 heat treatment. Secondly, with the aim of designing new alloy compositions and to examine the phases and microstructures of SLM Al-Cu alloys and to correlate their microstructures with the observed mechanical properties, Al-xCu (x = 4.5, 6, 20, 33 and 40 wt. %) alloys have been synthesized in-situ by SLM from mixtures of Al-4.5Cu and Cu powders. The results indicate that the insufficient Cu solute diffusion during the layer-by-layer processing results in an inhomogeneous microstructure around the introduced Cu powders. With increasing Cu content, the Al2Cu phase in the alloys increases improving the strength of the material. These results show that powder mixtures can be used for the synthesis of SLM composites but the reaction between the matrix and the second-phase should be considered carefully. Thirdly, the TiB2/Al-Cu-Mg-Si composite was also designed and fabricated successfully by SLM and it shows a higher strength than the unreinforced SLM alloy before and after T6 heat treatment. Finally, an Al-12Si/Al-3.5Cu-1.5Mg-1Si hybrid with a good interface was fabricated successfully. This hybrid alloy shows a good yield strength and elongation at room temperature, indicating an effective potential of selective laser melting in the field of hybrid manufacturing.

Additiv tillverkning (AM) är en växande tillverkningsteknologi som har många lovande tekniska, ekologiska och ekonomiska aspekter. Selektiv lasersmältning (SLM) är den AM-metod som står i framkanten av den utveckling som sker inom teknologin. SLM har kapabiliteten att tillverka detaljer med jämförbart goda mekaniska egenskaper gentemot konventionella tillverkningsmetoder men drabbas av vanligt förekommande defekter som hämmar dess möjligheter att bli en mer använd bearbetningsmetod i tillverkningsindustrin. I detta arbete, som tar an formen av en State of the Art Rapport, presenteras SLM-metoden på en teknisk nivå, den jämförs med andra AM-metoder samt med konventionell tillverkning, flera metaller och legeringar som finns tillgängliga för bearbetning presenteras och dess senaste utvecklingar samt framtid presenteras och diskuteras. / Additive manufacturing (AM) is a growing manufacturing technology which has many promising technical, ecological, and economical aspects. Selective Laser Melting (SLM) is the AM-method which stands on the forefront of the development which is taking place in this technology. SLM has the capability to produce components with relatively good mechanical characteristics as compared to conventional manufacturing methods. However, the method is suffering from common defects which inhibits its chances to become a more widely-used method in the manufacturing industry. In this work, which takes on the form of a State of the Art Report, the SLM-method is presented on a technical level. It is then put in comparison to other AM-methods and conventional manufacturing as a whole. Some of the metals and alloys available for SLM are listed. The latest developments in SLM are presented and lastly, the future developments of SLM is discussed.