Journal of Materials Processing Technology, Feb 1, 2021
Abstract Poor powder catchment efficiency, is a limiting factor in the adoption of Directed Energ... more Abstract Poor powder catchment efficiency, is a limiting factor in the adoption of Directed Energy Deposition for the processing of expensive materials, complex shapes and for the sake of energy efficiency. This study demonstrates a novel approach to improve powder catchment efficiency using a magnetic field to direct ferritic steel powder during deposition. Powder catchment efficiency increased to a value of 56% on a flat plane, compared to 26% under the same conditions without magnetic assistance. The mild steel substrate, being ferromagnetic, permitted greater magnetic manipulation of powder and higher powder catchment, compared to the austenitic stainless steel, which is essentially non-magnetic. It is proposed that the increase in powder catchment comes about by both the increased concentration of powder directly beneath the nozzle when passing over a magnet, as well as pre-loading of powder over the positions of magnets, due to rebounding particles, prior to the laser beam reaching them. Magnetic assistance was also shown to significantly improve catchment efficiency at substrate inclination angles of up to 45°. In addition, evidence of compression of deposited tracks was also seen on mild steel when magnets were used. Magnetic assistance therefore has significant potential as a process augmentation for improving material and energy efficiency in directed energy deposition, with the benefit of being able to be retrofitted to existing setups.
International Congress on Applications of Lasers & Electro-Optics, 2007
Direct metal deposition using a wire fed high power diode laser is a feasible process to form mul... more Direct metal deposition using a wire fed high power diode laser is a feasible process to form multiple layers of Waspaloy deposit at excellent deposition rates. In conjunction with a manipulation system, a complex three-dimensional structure could be fabricated offering promising applications for repair, feature addition and new component manufacture. Understanding the microstructure and mechanical properties of the material, especially one such as Waspaloy which is used in aerospace engines, is crucial to ensure its performance. Building parts layer-by-layer causes dynamic changes in the underlying substrate and the previously deposited layers due to the thermal cycling experienced. The heating and cooling rates during the deposition process affect the microstructure of the alloy which has an important impact on the mechanical properties of the material.The objective of this study is to evaluate the microstructural evolution during deposition, the changes in microhardness when multiple layers are deposited and to relate these to the thermal cycles arising from layer deposition.Direct metal deposition using a wire fed high power diode laser is a feasible process to form multiple layers of Waspaloy deposit at excellent deposition rates. In conjunction with a manipulation system, a complex three-dimensional structure could be fabricated offering promising applications for repair, feature addition and new component manufacture. Understanding the microstructure and mechanical properties of the material, especially one such as Waspaloy which is used in aerospace engines, is crucial to ensure its performance. Building parts layer-by-layer causes dynamic changes in the underlying substrate and the previously deposited layers due to the thermal cycling experienced. The heating and cooling rates during the deposition process affect the microstructure of the alloy which has an important impact on the mechanical properties of the material.The objective of this study is to evaluate the microstructural evolution during deposition, the changes in microhardness when multiple layers are deposit...
Journal of Materials Processing Technology, Feb 1, 2021
Abstract Poor powder catchment efficiency, is a limiting factor in the adoption of Directed Energ... more Abstract Poor powder catchment efficiency, is a limiting factor in the adoption of Directed Energy Deposition for the processing of expensive materials, complex shapes and for the sake of energy efficiency. This study demonstrates a novel approach to improve powder catchment efficiency using a magnetic field to direct ferritic steel powder during deposition. Powder catchment efficiency increased to a value of 56% on a flat plane, compared to 26% under the same conditions without magnetic assistance. The mild steel substrate, being ferromagnetic, permitted greater magnetic manipulation of powder and higher powder catchment, compared to the austenitic stainless steel, which is essentially non-magnetic. It is proposed that the increase in powder catchment comes about by both the increased concentration of powder directly beneath the nozzle when passing over a magnet, as well as pre-loading of powder over the positions of magnets, due to rebounding particles, prior to the laser beam reaching them. Magnetic assistance was also shown to significantly improve catchment efficiency at substrate inclination angles of up to 45°. In addition, evidence of compression of deposited tracks was also seen on mild steel when magnets were used. Magnetic assistance therefore has significant potential as a process augmentation for improving material and energy efficiency in directed energy deposition, with the benefit of being able to be retrofitted to existing setups.
International Congress on Applications of Lasers & Electro-Optics, 2007
Direct metal deposition using a wire fed high power diode laser is a feasible process to form mul... more Direct metal deposition using a wire fed high power diode laser is a feasible process to form multiple layers of Waspaloy deposit at excellent deposition rates. In conjunction with a manipulation system, a complex three-dimensional structure could be fabricated offering promising applications for repair, feature addition and new component manufacture. Understanding the microstructure and mechanical properties of the material, especially one such as Waspaloy which is used in aerospace engines, is crucial to ensure its performance. Building parts layer-by-layer causes dynamic changes in the underlying substrate and the previously deposited layers due to the thermal cycling experienced. The heating and cooling rates during the deposition process affect the microstructure of the alloy which has an important impact on the mechanical properties of the material.The objective of this study is to evaluate the microstructural evolution during deposition, the changes in microhardness when multiple layers are deposited and to relate these to the thermal cycles arising from layer deposition.Direct metal deposition using a wire fed high power diode laser is a feasible process to form multiple layers of Waspaloy deposit at excellent deposition rates. In conjunction with a manipulation system, a complex three-dimensional structure could be fabricated offering promising applications for repair, feature addition and new component manufacture. Understanding the microstructure and mechanical properties of the material, especially one such as Waspaloy which is used in aerospace engines, is crucial to ensure its performance. Building parts layer-by-layer causes dynamic changes in the underlying substrate and the previously deposited layers due to the thermal cycling experienced. The heating and cooling rates during the deposition process affect the microstructure of the alloy which has an important impact on the mechanical properties of the material.The objective of this study is to evaluate the microstructural evolution during deposition, the changes in microhardness when multiple layers are deposit...
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Papers by Joel Segal