Variation of laser energy transfer efficiency with weld pool depth

Fuerschbach, P.W.; MacCallum, Danny O’Neill

doi:10.2351/1.5058947

Cited by 8 publications

(4 citation statements)

References 4 publications

(3 reference statements)

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“…The thermal boundary conditions used in the model also need validation. Effective laser absorptivity levels used in this effort are typical of those used by other authors (Fuerschbach and MacCallum 1995;Ki, Mohanty et al 2001), but should be experimentally verified. Several simplifying assumptions for non-keyholeing processes were also incorporated in this model.…”

Section: Comparison Of Predictions and Experimentsmentioning

confidence: 83%

Solidification Diagnostics for Joining and Microstructural Simulations

Robino¹,

Hall²,

Brooks³

et al. 2003

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Solidification is an important aspect of welding, brazing, soldering, LENS fabrication, and casting. The current trend toward utilizing large-scale process simulations and materials response models for simulation-based engineering is driving the development of new modeling techniques. However, the effective utilization of these models is, in many cases, limited by a lack of fundamental understanding of the physical processes and interactions involved. In addition, experimental validation of model predictions is required. We have developed new and expanded experimental techniques, particularly those needed for insitu measurement of the morphological and kinetic features of the solidification process. The new high-speed, high-resolution video techniques and data extraction methods developed in this work have been used to identify several unexpected features of the solidification process, including the observation that the solidification front is often far more dynamic than previously thought. In order to demonstrate the utility of the video techniques, correlations have been made between the in-situ observations and the final solidification microstructure. Experimental methods for determination of the solidification velocity in highly dynamic pulsed laser welds have been developed, implemented, and used to validate and refine laser welding models. Using post solidification metallographic techniques, we have discovered a previously unreported orientation relationship between ferrite and austenite in the Fe-Cr-Ni alloy system, and have characterized the conditions under which this new relationship develops. Taken together, the work has expanded both our understanding of, and our ability to characterize, solidification phenomena in complex alloy systems and processes.

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Section: Comparison Of Predictions and Experimentsmentioning

confidence: 83%

Solidification Diagnostics for Joining and Microstructural Simulations

Robino¹,

Hall²,

Brooks³

et al. 2003

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show abstract

“…This absorption mechanism yields high a because laser light is effectively absorbed by the vapor column and weld pool cavity, which minimizes laser beam reflective losses because of the occurrence of multiple internal reflections within the cavity. [9] Laser deposition under these conditions would prove to be detrimental to part buildup during the LENS process, because previously deposited layers will be destroyed and part tolerance will subsequently be degraded. Laser beam irradiance, or power density (W/mm 2 ), is defined as laser output power over the laser beam spot size.…”

Section: A Laser Energy Transfer Efficiencymentioning

confidence: 99%

“…Equations [9] and [10] are thus semiempirical equations that can be used to estimate deposition efficiency as a function of ⌫, which in turn is a function of process efficiencies and processing parameters such as laser power and travel speed. …”

Section: Deposition Efficiencymentioning

confidence: 99%

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Process efficiency measurements in the laser engineered net shaping process

Unocic

DuPont

2004

Metall Mater Trans B

122

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A study of laser energy transfer efficiency, melting efficiency, and deposition efficiency has been conducted for the laser-engineered net-shaping process (LENS) for H-13 tool steel and copper powder deposits on H-13 tool steel substrates. This study focused on the effects of laser deposition processing parameters (laser power, travel speed, and powder mass flow rate) on laser beam absorption by the substrate material. Measurements revealed that laser energy transfer efficiency ranged from 30 to 50 pct. Laser beam coupling was found to be relatively insensitive to the range of processing parameters tested. Melting efficiency was found to increase with increasing laser input power, travel speed, and powder mass flow rate. A dimensionless parameter model that has been used to predict melting efficiency for laser beam welding processing was investigated for the LENS process. From these results, a semiempirical model was developed specifically for the LENS processing window. Deposition efficiency was also investigated and results show that under optimum processing conditions, the maximum deposition efficiency was approximately 14 pct. A semiempirical relation was developed to estimate deposition efficiency as a function of process efficiencies and LENS processing parameters. Knowledge of LENS process efficiencies measured in this study is useful to develop accurate heat flow and solidification models for the LENS process.

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Parametric study of melt pool geometry in hybrid plasma arc-laser melting process for additive manufacturing application

et al. 2023

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Wire-based hybrid arc-laser additive manufacturing is suitable for producing large metallic parts (metres in scale) with high deposition rates and near-net-shape. In this process, the surface quality and dimensional accuracy of the deposited parts are determined by the melt pool geometry. However, how to control the melt pool in the hybrid process is complex due to the multiple parameters that can be used. In this study, control of melt pool geometry by investigating different process parameters, including laser power, travel direction, arc-laser separation distance, laser beam size, and arc current in the hybrid plasma transferred arc (PTA)-laser process, was studied systematically. It was found that a larger melt pool was achieved with the PTA-leading configuration compared to that with the laser-leading configuration due to a higher laser absorption occurred with the former configuration. The melt pool was enlarged by either increasing the laser power or arc current due to the increased energy input. However, if the laser power density is high enough to determine the melt pool depth, the increasing arc current has very little effect on melt pool depth but only increases the melt pool width. In addition, the melt pool became shallower and wider when using a larger laser beam. The arc-laser separation distance had a minor effect on the melt pool geometry due to the fixed energy input used in the studied cases. The results of this study provide a reference for melt pool control in wire-based hybrid arc-laser additive manufacturing.

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Variation of laser energy transfer efficiency with weld pool depth

Cited by 8 publications

References 4 publications

Solidification Diagnostics for Joining and Microstructural Simulations

Solidification Diagnostics for Joining and Microstructural Simulations

Process efficiency measurements in the laser engineered net shaping process

Parametric study of melt pool geometry in hybrid plasma arc-laser melting process for additive manufacturing application

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