Bohlen, Annika
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Bohlen, Annika
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Bohlen, Annika
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Item type:Publication, High-speed laser melt injection for wear protection of skin-pass rolls(BIAS Verlag, 2022-11); ; ; ; Laser melt injection (LMI) is a technology for producing metal matrix composite (MMC) layers on tools such as skin-pass rolls by injecting hard particles into a laser-induced weld pool. However, low process speeds prevent the application of laser melt injection on a large scale. To overcome this drawback, a new approach is presented: High-speed laser melt injection (HSLMI) is a promising method for generating highly wear-resistant MMC-layers on tools with high productivity. For the first time, high process speeds of up to 100 m/min were reached with HSLMI of spherical fused tungsten carbide (SFTC) particles into the steel 1.2362 that is used for skin-pass rolls. It was found that both the crack susceptibility and the SFTC dissolution can be reduced significantly by increasing the process speed. The wear behavior of the MMC layers was studied in a pin-on-plate test. It was found that the SFTC reinforcement leads to a significant improvement in wear resistance over the non-reinforced steel substrate. The wear volume was reduced from 3.6 mm³ to 0.1 mm³ to 0.3 mm³ by an SFTC particle-reinforcement.journal article288 226 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, 515 nm wavelength laser for laser melt injection of high-quality MMC in Cu-ETP(BIAS Verlag, 2022-11); ; ; ; Laser melt injection (LMI) is used to improve abrasive wear resistance by building a metal matrix composite (MMC) layer in highly loaded tool surfaces. But LMI for highly conductive and highly reflective materials like copper can be very challenging. Nowadays high-power laser beam sources with visible wavelengths are available enabling LMI in these materials. This paper shows a suitable process window for LMI with 515 nm wavelength laser in pure copper with spherical fused tungsten carbide as reinforcing phase. High-quality MMC can be manufactured by using laser power intensities in the range of 104 W/cm² and conduction heating of the matrix mate-rial between 300 °C and 400 °C. The microstructure exhibits only a few imperfections and has a high particle content of 44 %.journal article288 231 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Influence of powder feed parameters on the powder stream in laser metal deposition (LMD) by high-speed and high-resolution imaging(BIAS Verlag, 2022-11); ; ; ; Laser metal deposition (LMD) is a blown powder process used for the additive manufacturing of large components or the generation of functional geometries on semi-finished parts. In LMD laser intensity and powder mass flow distribution within the process zone must be precisely matched for a welding bead of predefined shape and a consistent layer quality. Therefore, the present work analyses the powder stream of a single injector that is commonly used for discrete coaxial nozzles in LMD. Several powder size classes are investigated in a range of 45 μm and 106 μm. The influence of carrier gas flow rate and powder mass flow rate variations on powder stream characteristics like particle velocity and propagation were determined up to a distance of 10 mm from the nozzle by high-speed imaging at a frequency of 30 kHz with a high spatial resolution. It was found that particle velocity depends mainly on carrier gas flow rate and particle size. Additionally, the measurement shows that the divergence increases for higher distances and higher particle sizes.journal article370 364 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Ausbreitung des Pulverstrahls für das Laser-Pulver-Auftragschweißen(2025-07-08); ; 112 119