Powder incorporation and spatter formation in high deposition rate blown powder directed energy deposition

Abstract The effects of Ti-6Al-4V part size on its temperature distribution during the blown-powder directed energy deposition (DED) process was investigated through dual-thermographic monitoring and a unique modeling technique. Results demonstrate that the duration of dwell times presented to be a significant contributing factor affecting the rate at which a steady-state temperature field is achieved. As a result, the longer wall took significantly more layers/time to achieve a uniform temperature profile within the wall. Maximum and average melt pool temperatures appear to be near independent of part size at a steady state. Finite element simulation results showed that a quasi-steady melt pool temperature may be unique to a layer, especially during earlier cladding process near the substrate and that the layer-wise steady melt pool was achieved within the first few seconds of track scanning. A proposed fin modeling-based temperature distribution was found to predict the thermal profile in a ‘substrate affected zone’ (SAZ) along the scan direction within 5%. A method to predict the onset of the SAZ has also been proposed. Process parameters used for the DED of component volumes are not necessarily optimal for thin-walled structures due to significantly less thermal capacity.

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Thermal Monitoring and Modeling of Ti-6Al-4V Thin Wall Temperature Distribution During Blown Powder Laser Directed Energy Deposition

Volume 1: Additive Manufacturing; Advanced Materials Manufacturing; Biomanufacturing; Life Cycle Engineering; Manufacturing Equipment and Automation ◽

10.1115/msec2021-63263 ◽

2021 ◽

Author(s):

Basil J. Paudel ◽

Garrett J. Marshall ◽

Scott M. Thompson

Keyword(s):

Steady State ◽

Temperature Distribution ◽

Energy Deposition ◽

Thermal Capacity ◽

Thin Wall ◽

Thin Walled Structures ◽

Melt Pool ◽

Directed Energy Deposition ◽

Directed Energy ◽

Blown Powder

Abstract The effects of Ti-6Al-4V part size on its temperature distribution during the blown-powder directed energy deposition-laser (DED-L) process was investigated through dual-thermographic monitoring and a unique modeling technique. Results demonstrate that the duration of dwell times are a significant contributing factor affecting the rate at which a steady-state temperature field is achieved. Longer walls took significantly more layers/time to achieve a uniform temperature profile. Maximum and average melt pool temperatures appear to be near independent of part size at a steady state. Finite element simulation results show that a quasi-steady melt pool temperature may be unique to a layer, especially for layers near the substrate. Layer-wise steady melt pool temperatures were achieved within the first few seconds of track scanning. A proposed fin modeling-based temperature distribution was found to predict the thermal profile in a ‘substrate affected zone’ (SAZ) along the scan direction within 5%. A method to predict the onset of the SAZ has also been proposed. Process parameters used for the DED-L of component volumes are not necessarily optimal for thin-walled structures due to their significantly lower thermal capacity.

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Structural Integrity Assessments for Validating Directed Energy Deposition Repairs of Integrally Bladed Rotor

Volume 10B: Structures and Dynamics ◽

10.1115/gt2020-14361 ◽

2020 ◽

Author(s):

Onome Scott-Emuakpor ◽

Brian Runyon ◽

Tommy George ◽

Andrew Goldin ◽

Casey Holycross ◽

...

Keyword(s):

Energy Deposition ◽

Structural Integrity ◽

Low Cycle Fatigue ◽

Cycle Fatigue ◽

Component Level ◽

Integrity Assessment ◽

Repair Processes ◽

Directed Energy Deposition ◽

Directed Energy ◽

Blown Powder

Abstract Considerable steps to assess the structural capability of laser directed energy deposition (DED) aim to determine the viability of repair processes for integrally bladed rotors (IBRs). Two laser DED processes are under investigation in this study: wire fed and blown powder feedstock. Using a small subsonic Titanium 6Al-4V fan as the component of interest, a series of tests and associated models for laboratory specimens, subcomponents, and components are necessary for proper assessment of material structural properties pertaining to the intended mission of the IBR. Experimentation on laboratory specimens acquire properties such as tensile strength, elongation, low cycle fatigue (LCF), high cycle fatigue (HCF), crack growth rate, and fracture toughness. Subcomponent test articles fabrication occurs by sectioning an operational IBR into individual blades for vibration HCF assessment. Component level testing focuses on LCF and overspeed strength acquired from spin rig testing. Even though the full IBR repair validation of laboratory specimen, subcomponent, and component testing has yet to be completed, the results to-date for laser DED repairs are promising. Furthermore, this plan for structural integrity assessment can serve as a reference for validation of future IBR repair processes.

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