A concept for a hydrodynamic model of keyhole formation and support during laser welding

Semak, V. V.; Hopkins, John A.; McCay, Mary Helen; McCay, T. D.

doi:10.2351/1.5058848

Cited by 34 publications

(38 citation statements)

References 9 publications

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“…LST created patterns by vaporization and recoil pressure mechanisms [33]. A melted layer with~1 μm thickness can be observed in the bottom of the pattern in addition to resolidified matter on the edges (Fig.…”

Section: Time To Spallation Of the Top-coat Under High Temperature Oxmentioning

confidence: 99%

High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

Kromer

Cormier

Costil

et al. 2018

Surface and Coatings Technology

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Thermal barrier coating systems are usually build-up with bond coats to ensure a good adhesion of the ceramic top coat and to protect the substrate against oxidation and corrosion. Such system is often subjected to complex thermo-mechanical loading. Because of the very different damage processes encountered during service operations, a simplified system was investigated by removing the bond-coat. Recently adhesion bond strength was enhanced using laser surface texturing of the substrate in thermal spraying processes. Atmospheric plasma spray yttria-stabilized-zirconia thermal barrier coating system was deposited on the Ni-based AM1 single crystalline superalloy without bond coat. Adhesion bond strength was already increased compared to conventional processing method. Top coat durability was evaluated at high temperature and damage mechanisms were studied. Isothermal and cyclic oxidation tests showed durability of 1000 h and 400 cycles at 1100°C. The oxidation mechanisms at the substrate/top coat interface changed due to fast solidification during the laser texturing process. Then, TBC system was studied under high temperature mechanical solicitation in tension creep. The textured interfaces were not damaged after 1% creep strain while top-coat/substrate interfacial cracking was observed for grit-blasted specimens. Moreover, no preferential crack development in the substrate was observed. Patterns provided an enhanced adhesion by changing the stress distribution near the interface.

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Section: Time To Spallation Of the Top-coat Under High Temperature Oxmentioning

confidence: 99%

High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

Kromer

Cormier

Costil

et al. 2018

Surface and Coatings Technology

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show abstract

“…Because of the nonuniform Fresnel absorption and various attenuation factors (i.e., plume, plasma, etc.) [26,41], the effective laser energy absorbed by the sample fluctuates considerably over time and location. A higher laser absorption tends to generate a higher vapor flux and thus a higher vapor dynamic pressure, which then supports a shorter formation time of the tonguelike protrusion.…”

Section: Internal Adaptive Mechanism For the Tonguelike Protrusionmentioning

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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“…Additionally, obtaining the keyhole geometry is more difficult than describing the conduction and convection in the melt pool. Since the keyhole is mainly generated by the recoil pressure of the laser, which ejects molten material from the area [246], most keyhole models utilize hydrodynamic equations, coupled with equations that track the dynamic change of the keyhole wall. This allows simulations to track the interaction between the keyhole and the molten pool [247].…”

Section: Fluid Dynamics Methodsmentioning

confidence: 99%

Survey of Modeling and Simulation Techniques for Advanced Manufacturing Technologies Volume I – Predicting Initial Microstructures

Nicolas

Chakraborty

Paulson

et al. 2020

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This report summarizes the current state of modeling and simulation methods for predicting the initial structure and properties of material in components assembled using advanced manufacturing technologies (AMTs). The report is the first volume in a two-volume series. This first volume focuses on predicting initial microstructures of AM material. The second volume discusses predicting material properties given the initial microstructure. The focus is on technologies of particular relevance to the design and manufacture of nuclear reactor components. The purpose of the report is to help develop the technical knowledge base to support regulatory decisions that will be needed to assess nuclear components manufactured with AMTs as these components are installed at nuclear power plants (NPPs). The report develops a list of AMTs of particular interest to the NRC and summarizes the key microstructural features and corresponding processing parameters relevant to each technology. Further sections describe available physically-based and data-driven prediction methods and survey widely available software tools. The report concludes with a summary of gaps that may be of particular interest to the NRC when evaluating modeling and simulation methods for AMTs. v

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A concept for a hydrodynamic model of keyhole formation and support during laser welding

Cited by 34 publications

References 9 publications

High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

High temperature durability of a bond-coatless plasma-sprayed thermal barrier coating system with laser textured Ni-based single crystal substrate

Bulk-Explosion-Induced Metal Spattering During Laser Processing

Survey of Modeling and Simulation Techniques for Advanced Manufacturing Technologies Volume I – Predicting Initial Microstructures

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