Ultrafast dynamics of laser-metal interactions in additive manufacturing alloys captured by in situ X-ray imaging

Martin, Aiden A.; Calta, Nicholas P.; Hammons, Joshua A.; Khairallah, Saad A.; Nielsen, Michael H.; Shuttlesworth, R.; Sinclair, Nicholas; Matthews, Manyalibo J.; Jeffries, J. R.; Willey, Trevor M.; Lee, Jonathan R. I.

doi:10.1016/j.mtadv.2019.01.001

Cited by 133 publications

(79 citation statements)

References 38 publications

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“…Now for 1 < R < 2-3, the reflected beam from the KH front is not very strongly deflected downwards [29]; it is quite horizontal and it irradiates the KH rear wall, the height of which is equivalent to that of the KH front. (See for example, numerical simulations of Martin et al [33]). But the effect of this interaction on the KH rear wall depends of the location of this wall, which is defined by the length of the KH aperture itself controlled by the welding speed.…”

Section: Kh Absorptivity Variationsmentioning

confidence: 99%

“…Therefore, when R begins to be greater than one, the interaction of the reflected beam on this rather close KH rear wall increases the overall absorptivity of the incoming laser beam. Typically, for these conditions, after this second interaction of the incoming beam, if one considers that the reflected beam exits from this KH aperture (because of some inclination of the KH rear wall towards the rear melt pool due to the melt flow [33]), the total absorptivity after these two reflections would be 1 − (1 − A0) 2 , where A0 is a characteristic absorptivity of the melted KH surface. Then from there, if R continues to increase, the KH absorptivity increases further due to the increasing number of multi-reflections.…”

Section: Kh Absorptivity Variationsmentioning

confidence: 99%

“…The multi-physics simulations of Martin et al [33] that take into account ray-tracing of the laser beam propagation inside the KH, show that due to this multi-reflections process, the rear KH wall can be directly irradiated by the reflected beam from the KH front wall when its inclination is about 45 • . The resulting recoil pressure on this rear wall of the KH prevents the KH from closing due to surface tension and controls the position of the rear wall.…”

Section: Welding Experimentsmentioning

confidence: 99%

“…Figure 11. (a) Example of multi-physics simulations of the multi-reflections mechanism inside the KH [33]. Sequence of events leading to melt pool perturbation: (b) A low aspect ratio KH is first generated.…”

Section: Welding Experimentsmentioning

confidence: 99%

“…One can understand that for these threshold conditions, the intensity distribution at the bottom of the depression that controls the recoil pressure, which roughly equilibrates the local surface tension pressure, can be easily perturbed by the unavoidable fluctuations of the KH surface. [33]. Sequence of events leading to melt pool perturbation: (b) A low aspect ratio KH is first generated.…”

Section: Spot-welding Experimentsmentioning

confidence: 99%

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Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

Fabbro

2020

Applied Sciences

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Depending of the laser operating parameters, several characteristic regimes of laser welding can be observed. At low welding speeds, the aspect ratio of the keyhole can be rather large with a rather vertical cylindrical shape, whereas at high welding speeds, low aspect ratios result, where only the keyhole front is mainly irradiated. For these different regimes, the dependence of the keyhole (KH) depth or the keyhole threshold, as a function of the operating parameters and material properties, is derived and their resulting scaling laws are surprisingly very similar. This approach allows us to analyze the keyhole behavior for these welding regimes, around their keyhole generation thresholds. Specific experiments confirm the occurrence and the behavior of these unstable keyholes for these conditions. Furthermore, recent experimental results can be analyzed using these approaches. Finally, this analysis allows us to define the aspect ratio range for the occurrence of this unstable behavior and to highlight the importance of laser absorptivity for this mechanism. Consequently, the use of a short wavelength laser for the reduction of these keyhole stability issues and the corresponding improvement of weld seam quality is emphasized.

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Section: Kh Absorptivity Variationsmentioning

confidence: 99%

Section: Kh Absorptivity Variationsmentioning

confidence: 99%

Section: Welding Experimentsmentioning

confidence: 99%

Section: Welding Experimentsmentioning

confidence: 99%

Section: Spot-welding Experimentsmentioning

confidence: 99%

See 3 more Smart Citations

Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

Fabbro

2020

Applied Sciences

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Overview of Metal Additive Manufacturing Technologies

2024

Metallic Powders for Additive Manufacturing

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Laser‐Based Additive Manufacturing Technologies for Aerospace Applications

2019

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Additive manufacturing (AM) is a transformative technology that has rapidly grown over the past decade. AM processes build parts layer by layer and have found applications in the aerospace, biomedical, and automotive fields. The technology holds particular promise for the aerospace industry due to the reduced process time, weight savings of parts, and opportunities for new material development. Herein, a review of laser-based AM processes, existing AM systems, and aerospace parts being fabricated is presented. It further explores the material properties and microstructure of printed samples with both powder bed fusion and direct energy deposition processes. The benefits and challenges associated with the widespread use of the technology are discussed with emphases on the aerospace sector. Finally, the steps required for parts produced by AM processes to become certified for use in aerospace applications are presented.

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Ultrafast dynamics of laser-metal interactions in additive manufacturing alloys captured by in situ X-ray imaging

Cited by 133 publications

References 38 publications

Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

Depth Dependence and Keyhole Stability at Threshold, for Different Laser Welding Regimes

Overview of Metal Additive Manufacturing Technologies

Laser‐Based Additive Manufacturing Technologies for Aerospace Applications

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