@inproceedings{KeimTetzlaffElger2020, author = {Keim, Simon and Tetzlaff, Ulrich and Elger, Gordon}, title = {The influence of different-sized Ni micro- and nanopowders on the processing and microstructural properties of Sn-Ag-Cu-solder with low Ag content}, booktitle = {Proceedings : IEEE 70th Electronic Components and Technology Conference : ECTC 2020}, publisher = {IEEE}, address = {Piscataway}, isbn = {978-1-7281-6180-8}, issn = {2377-5726}, doi = {https://doi.org/10.1109/ECTC32862.2020.00312}, pages = {2005 -- 2012}, year = {2020}, language = {en} } @article{GottwaltKubaschinskiWaltzetal.2023, author = {Gottwalt, Albin and Kubaschinski, Paul and Waltz, Manuela and Tetzlaff, Ulrich}, title = {Influence of the cutting method on the fatigue life and crack initiation of non-oriented electrical steel sheets}, volume = {2024}, pages = {108073}, journal = {International Journal of Fatigue}, number = {180}, publisher = {Elsevier}, address = {Oxford}, issn = {1879-3452}, doi = {https://doi.org/10.1016/j.ijfatigue.2023.108073}, year = {2023}, abstract = {The fatigue behavior of thin electrical steel sheets under cyclic loading is investigated in dependence on the edge surface. Therefore, four different edge conditions are compared, whereas the edge is either laser cut, shear cut, wire cut, or polished. Strain- and stress-controlled fatigue tests are performed to determine S-N curves in the low cycle regime as well as in the high cycle regime. Microstructural data is collected by non-contacting (optical) Profilometry, Nanoindentation, X-Ray Diffraction, and Electron Backscatter Diffraction to understand the differences in fatigue life by considering surface roughness, residual stresses, hardness, and microstructure. Shear cut specimens achieve the lowest fatigue life, while the other edge conditions reach relatively similar values in the LCF regime. Crack initiation is mainly intergranular in the case of defect-free edges. This tendency has a considerable influence on the observed fatigue behavior.}, language = {en} } @article{GottwaltKubaschinskiWaltzetal.2023, author = {Gottwalt, Albin and Kubaschinski, Paul and Waltz, Manuela and V{\"o}lkl, Rainer and Glatzel, Uwe and Tetzlaff, Ulrich}, title = {Cyclic deformation behavior of non-oriented electrical steel sheets}, volume = {2023}, pages = {145684}, journal = {Materials Science and Engineering: A}, number = {886}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0921-5093}, doi = {https://doi.org/10.1016/j.msea.2023.145684}, year = {2023}, language = {en} } @article{SchmittGottwaltWinkleretal.2021, author = {Schmitt, Matthias and Gottwalt, Albin and Winkler, Jakob and Tobie, Thomas and Schlick, Georg and Stahl, Karsten and Tetzlaff, Ulrich and Schlip, Johannes and Reinhart, Gunther}, title = {Carbon Particle In-Situ Alloying of the Case-Hardening Steel 16MnCr5 in Laser Powder Bed Fusion}, volume = {11}, pages = {11060896}, journal = {Metals}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2075-4701}, doi = {https://doi.org/10.3390/met11060896}, year = {2021}, abstract = {The carbon content of steel affects many of its essential properties, e.g., hardness and mechanical strength. In the powder bed fusion process of metals using a laser beam (PBF-LB/M), usually, pre-alloyed metal powder is solidified layer-by-layer using a laser beam to create parts. A reduction of the carbon content in steels is observed during this process. This study examines adding carbon particles to the metal powder and in situ alloying in the PBF-LB/M process as a countermeasure. Suitable carbon particles are selected and their effect on the particle size distribution and homogeneity of the mixtures is analysed. The workability in PBF-LB is then shown. This is followed by an evaluation of the resulting mechanical properties (hardness and mechanical strength) and microstructure in the as-built state and the state after heat treatment. Furthermore, potential use cases like multi-material or functionally graded parts are discussed.}, language = {en} } @article{KiehlScheidGrafetal.2022, author = {Kiehl, Maximilian and Scheid, Adriano and Graf, Karin and Ernst, Benedikt and Tetzlaff, Ulrich}, title = {Coaxial Laser Cladding of Cobalt-Base Alloy Stellite™ 6 on Grey Cast Iron Analysis of the Microstructural and Mechanical Properties Depending on the Laser Power}, volume = {32}, journal = {Journal of Materials Engineering and Performance}, number = {8}, publisher = {Springer}, address = {New York}, issn = {1544-1024}, doi = {https://doi.org/10.1007/s11665-022-07358-3}, pages = {3821 -- 3838}, year = {2022}, abstract = {A high-power diode laser was used to generate single- and multi-bead coatings of Stellite™ 6 by coaxial laser cladding over flat grey cast iron (EN-GJLP-200) as a preliminary study to develop a wear and corrosion resistant coating for brake disks on a cost-effective substrate. In this article, we have focused on a detailed quantitative analysis of the effect of different laser powers (1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 kW) on the bead geometry, dilution, microstructure, and hardness. Coatings dilution or composition depends directly on the laser power as well as bead geometry. The typical microstructure of the coatings comprises a solid solution of α (hcp)- and β (fcc)-Co with a dendritic structure as a metal matrix and an interdendritic lamellar eutectic, which contains predominantly β-Co, chromium carbides Cr7C3 and Cr23C6 as well as blocky tungsten carbide W2C. Coating hardness depends on the chemical composition and microstructure that is modified by the deposition parameters. Low laser power results in high carbide fraction and most refined microstructures, accounting for harder coatings.}, language = {en} } @article{KubaschinskiGottwaltTetzlaffetal.2023, author = {Kubaschinski, Paul and Gottwalt, Albin and Tetzlaff, Ulrich and Altenbach, Holm and Waltz, Manuela}, title = {Modelling and simulation of the hardness profile and its effect on the stress-strain behaviour of punched electrical steel sheets}, volume = {54}, journal = {Materials Science \& Engineering Technology}, number = {4}, publisher = {Wiley}, address = {Weinheim}, issn = {0933-5137}, doi = {https://doi.org/10.1002/mawe.202200283}, pages = {512 -- 526}, year = {2023}, abstract = {The shear cutting of electrical steel sheets has a significant influence on the magnetic and mechanical material properties. Due to plastic deformation and strain hardening in the area of the punched edge, the electrical steel sheets exhibit a characteristic hardness profile. This study deals with the modelling of the resulting hardness profile by means of finite-element simulations. Elastic-plastic material properties are obtained from spherical nanoindentation testing as a function of the local hardness. In particular, representative stress-strain values are determined by applying Tabor's concept of indentation stress-strain curves. The choice of the appropriate stress- and strain-constraint factors is discussed with respect to the nanoindentation test setup used. Following this, the representative stress-strain values are analytically described to determine true stress-strain curves for the local assignment of different material models depending on the hardness. The implementation of the modelling approach in a finite-element simulation is presented for a punched electrical steel sheet specimen under monotonic loading. The simulation results are basically in good agreement with experimental data and confirm the expected influence on the mechanical material behaviour due to the shear cutting process.}, language = {en} } @article{HandwerkerKesslerMarzbanietal.2022, author = {Handwerker, Michael and Kessler, J{\"o}rg and Marzbani, Hormoz and Tetzlaff, Ulrich}, title = {Pressure and heat treatment of continuous fibre reinforced thermoplastics produced by fused filament fabrication}, volume = {8}, journal = {Progress in Additive Manufacturing}, number = {2}, publisher = {Springer}, address = {Cham}, issn = {2363-9520}, doi = {https://doi.org/10.1007/s40964-022-00315-5}, pages = {99 -- 116}, year = {2022}, abstract = {Fused filament fabrication allows for the additive manufacturing of complex geometries without requiring moulds. However, due to large air voids and poor layer adhesion, the mechanical properties of parts manufactured using fused filament fabrication lag behind those of parts manufactured using conventional techniques. A previous study found that the tensile strength and Young's modulus of such parts could be increased by a heat-treatment process. However, large air voids were still present after annealing. This study, therefore, investigates the influence of a post-pressure-treatment process on the mechanical performance and the air void ratio of continuous glass fibre-reinforced polyamide 6 in the directions perpendicular to the fibres. Without the treatment, Young's modulus on the plane parallel to the printing bed is eight times higher than Young's modulus perpendicular to it. Annealing at 1 MPa homogenises the material and leads to a significant increase of both the tensile strength (55 MPa) and Young's modulus (5 GPa). Increasing the pressure to 3 MPa only slightly increases the mechanical performance, whereas a further increase to 6 MPa causes no significant changes.}, language = {en} } @article{LemosFredelPyczaketal.2022, author = {Lemos, Georges and Fredel, M{\´a}rcio Celso and Pyczak, Florian and Tetzlaff, Ulrich}, title = {Creep resistance improvement of a polycrystalline Ni-based superalloy via TiC particles reinforcement}, volume = {2022}, pages = {143821}, journal = {Materials Science and Engineering: A}, number = {854}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4936}, doi = {https://doi.org/10.1016/j.msea.2022.143821}, year = {2022}, language = {en} } @article{ErnstKeimTetzlaff2022, author = {Ernst, Benedikt and Keim, Simon and Tetzlaff, Ulrich}, title = {On the anisotropic indentation modulus and anisotropic creep behavior of β-Sn characterized by nanoindentation methods}, volume = {2022}, pages = {143392}, journal = {Materials Science and Engineering: A}, number = {848}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-4936}, doi = {https://doi.org/10.1016/j.msea.2022.143392}, year = {2022}, language = {en} } @article{deSouzaPintoPereiraGutjahrPereiraetal.2023, author = {de Souza Pinto Pereira, Adriano and Gutjahr, Jhonattan and Pereira, Milton and Tetzlaff, Ulrich and Fredel, M{\´a}rcio Celso}, title = {Processability of thin-powdered Inconel X750 and TiC metal matrix composite by laser-directed energy deposition}, volume = {35}, pages = {042040}, journal = {Journal of Laser Applications}, number = {4}, publisher = {LIA}, address = {Orlando}, issn = {1042-346X}, doi = {https://doi.org/10.2351/7.0001134}, year = {2023}, language = {en} }