Steel surfaces have been coated with Co-based tungsten carbide (WC) in an additive printing process. This process leads to compact and extremely mechanically stable surfaces. We performed tribological measurements using WC counter bodies under dry conditions and severe mechanical load. Low coefficients of friction, even for rough surfaces, were found and the resulting wear rates were extraordinarily small, even when compared to high-quality PVD film with a similar composition. These findings suggest a wide field of application for this novel preparation process for wear-resistive surfaces.

Laser-Powder Bed Fusion brings new possibilities for the design of parts, e.g., cutter shafts with integrated cooling channels close to the contour. However, there are new challenges to dimensional accuracy in the production of thin-walled components, e.g., heat exchangers. High degrees of dimensional accuracy are necessary for the production of functional components. The aim is to already achieve these during the process, to reduce post-processing costs and time. In this work, thin-walled ring specimens of H13 tool steel are produced and used for the analysis of dimensional accuracy and residual stresses. Two different scanning strategies were evaluated. One is a stripe scan strategy, which was automatically generated and provided by the machine manufacturer, and a (manually designed) sectional scan strategy. The ring segment strategy is designed by manually segmenting the geometry, which results in a longer preparation time. The samples were printed in different diameters and analyzed with respect to the degree of accuracy and residual stresses. The dimensional accuracy of ring specimens could be improved by up to 81% with the introduced sectional strategy compared to the standard approach.

Most material removal in modern manufacturing is currently performed using tools with indexable inserts. Additive manufacturing allows for the creation of new, experimental insert shapes and, more importantly, internal structures, such as channels for coolant. This study deals with developing a process for efficiently manufacturing WC-Co specimens with internal coolant channels with a focus on obtaining a suitable microstructure and surface finish, especially inside the channels. The first part of this study covers the development of process parameters to achieve a microstructure without cracks and with minimal porosity. The next stage focuses solely on improving the surface quality of the parts. Special attention is given to the internal channels, where true surface area and surface quality are evaluated, as these characteristics greatly influence coolant flow. To conclude, WC-Co specimens were successfully manufactured and a microstructure with low porosity and no cracks was achieved and an effective parameter set was found. We have developed a process that produces parts with a surface roughness comparable to those of standard SLS manufacturing of steel parts, while still providing a high-quality internal microstructure. The most suitable parameter set resulted in a profile surface roughness of Ra 4 μm and Rz 31 μm and areal surface roughness of Sa 7 µm and Sz 125 µm.

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Invar alloys are used for high‐precision applications due to their invariance of the coefficient of thermal expansion over a temperature range up to about 250 °C. The present study determines the mechanical and corrosive properties of Invar 36 (64 % Iron – 36 % Nickel) specimens produced by laser powder bed fusion. Tensile specimens were fabricated to investigate the mechanical properties. The influence of a horizontal and vertical building orientation is considered. An apparent mechanical anisotropy depending on the respective building is observed. Based on this, further tensile specimens were stored in a hydrochloric acid pickling solution, a sulphate buffer solution and a sodium chloride solution to analyse the corrosion behaviour. The findings after eight weeks in the individual media show that outsourcing the Invar 36 specimens in a sulphate buffer solution results in significant changes in the mechanical properties, especially fracture elongation.