Transient dynamics of powder spattering in laser powder bed fusion additive manufacturing process revealed by in-situ high-speed high-energy x-ray imaging

Guo, Qilin; Zhao, Cang; Escano, Luis I.; Young, Zachary A.; Xiong, Lianghua; Fezzaa, Kamel; Everhart, Wes; Brown, Ben; Sun, Tao; Chen, Lianyi

doi:10.1016/j.actamat.2018.03.036

Cited by 331 publications

(158 citation statements)

References 31 publications

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“…Over the last few decades, the research community, through its endeavors, has been expanding our knowledge of the formation, development, and controls of laser spattering [13,14]. A few mechanisms were proposed to explain the laser-spattering phenomenon, which are mostly concerned with the local laser energy absorption, vapor plume dynamics, and melt flow [15,16]. The complex interplays among recoil pressure, vapor plume impact, and the surface tension of the molten metal are believed to be the cause of spattering.…”

Section: Introductionmentioning

confidence: 99%

Bulk-Explosion-Induced Metal Spattering During Laser Processing

Zhao

Guo

et al. 2019

Phys. Rev. X

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Spattering has been a problem in metal processing involving high-power lasers, like laser welding, machining, and recently, additive manufacturing. Limited by the capabilities of in situ diagnostic techniques, typically imaging with visible light or laboratory x-ray sources, a comprehensive understanding of the laser-spattering phenomenon, particularly the extremely fast spatters, has not been achieved yet. Here, using MHz single-pulse synchrotron-x-ray imaging, we probe the spattering behavior of Ti-6Al-4V with micrometer spatial resolution and subnanosecond temporal resolution. Combining direct experimental observations, quantitative image analysis, as well as numerical simulations, our study unravels a novel mechanism of laser spattering: The bulk explosion of a tonguelike protrusion forming on the front keyhole wall leads to the ligamentation of molten metal at the keyhole rims and the subsequent spattering. Our study confirms the critical role of melt and vapor flow in the laser-spattering process and opens a door to manufacturing spatter-and defect-free metal parts via precise control of keyhole dynamics.

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Section: Introductionmentioning

confidence: 99%

Bulk-Explosion-Induced Metal Spattering During Laser Processing

Zhao

Guo

et al. 2019

Phys. Rev. X

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“…[37] As AM is best suited for small part runs and reduced lead time, the precise control is more crucial than traditional manufacturing processes. Several studies even used high speed X-ray imaging to monitor the powder splattering dynamics [86] and the liquid/metal interactions in the melt pool. Several studies even used high speed X-ray imaging to monitor the powder splattering dynamics [86] and the liquid/metal interactions in the melt pool.…”

Section: Process Monitoring and Controlmentioning

confidence: 99%

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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“…Since the pump-probe delay should be scanned to map the temporal dynamics, it is necessary to irradiate multiple pump pulses for generating identical stimulations in the sample. Therefore, the conventional pump-probe methods are not fully compatible with non-repeating phenomena such as fluid dynamics 4 and explosion dynamics 5,6 . The demand has grown steadily for recording the entire sequence of dynamics induced by a single pump pulse 7,8 .…”

Section: Introductionmentioning

confidence: 99%

Single-shot imaging of microscopic dynamic scenes at 5 THz frame rates by time and spatial frequency multiplexing

Moon¹,

Yoon²,

Lim

et al. 2020

Opt. Express

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Femtosecond-scale ultrafast imaging is an essential tool for visualizing ultrafast dynamics in molecular biology, physical chemistry, atomic physics, and fluid dynamics. Pump-probe imaging and a streak camera are the most widely used techniques, but they are either demanding the repetitions of the same scene or sacrificing the number of imaging dimensions. Many interesting single-shot ultrafast imaging techniques have been developed in recent years for recording non-repetitive dynamic scenes. Nevertheless, there are still weaknesses in the number of frames, the number of image pixels, or spatial/temporal resolution. Here, we present a single-shot ultrafast microscopy that can capture more than a dozen frames at a time with the frame rate of 5 THz. We combine a spatial light modulator and a custom-made echelon for efficiently generating a large number of reference pulses with designed time delays and propagation angles. The single-shot recording of the interference image between these reference pulses with a sample pulse allows us to retrieve the stroboscopic images of the dynamic scene at the timing of the reference pulses. We demonstrated the recording of 14 temporal snapshots at a time, which is the largest to date, with the optimal temporal resolution set by the laser output pulse. Our ultrafast microscopy is highly scalable in the number of frames and temporal resolutions, and this will have profound impacts on uncovering the interesting spatio-temporal dynamics yet to be explored.

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Transient dynamics of powder spattering in laser powder bed fusion additive manufacturing process revealed by in-situ high-speed high-energy x-ray imaging

Cited by 331 publications

References 31 publications

Bulk-Explosion-Induced Metal Spattering During Laser Processing

Bulk-Explosion-Induced Metal Spattering During Laser Processing

Laser‐Based Additive Manufacturing Technologies for Aerospace Applications

Single-shot imaging of microscopic dynamic scenes at 5 THz frame rates by time and spatial frequency multiplexing

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