Direct measurements of temperature-dependent laser absorptivity of metal powders

Rubenchik, Alexander M.; Wu, Shuai; Mitchell, Scott C.; Golosker, Ilya V.; LeBlanc, M.M.; Peterson, N.

doi:10.1364/ao.54.007230

Cited by 78 publications

(21 citation statements)

References 8 publications

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“…This value demonstrates reasonable agreement with reported experimental results in the literature [69,70]. However, considering the difficulties associated with experimentally measuring absorptivity due to its dependence on multiple parameters (i.e., wavelength, temperature, oxidation, powder size, powder distribution, powder porosity), these experimental results might involve high uncertainty.…”

Section: Prediction Using the Calibrated Modelsupporting

confidence: 91%

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

Mahmoudi

Tapia

Karayagiz

et al. 2018

Integr Mater Manuf Innov

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Metal additive manufacturing (AM) typically suffers from high degree of variability in the properties/performance of the fabricated parts, particularly due to the lack of understanding and control over the physical mechanisms that govern microstructure formation during fabrication. This paper directly addresses an important problem in AM: the determination of the thermal history of the deposited material. Any attempts to link process to microstructure in AM would need to consider the thermal history of the material. In-situ monitoring only provides partial information and simulations may be necessary to have a comprehensive understanding of the thermo-physical conditions to which the deposited material is subjected. We address this in the present work through linking thermal models to experiments via a computationally efficient surrogate modeling approach based on multivariate Gaussian processes (MVGPs). The MVGPs are then used to calibrate the free parameters of the multi-physics models against experiments, sidestepping the use of prohibitively expensive Monte Carlo-based calibration. This framework thus makes it possible to efficiently evaluate the impact of varying process parameter inputs on the characteristics of the melt pool during AM. We demonstrate the framework on the calibration of a thermal model for Laser-Powder Bed Fusion AM of Ti-6Al-4V against experiments carried out over a wide window in the process parameter space. While this work deals with problems related to AM, its applicability is wider as the proposed framework could potentially be used in many other ICME-based problems where it is essential to link expensive computational materials science models to available experimental data.

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Section: Prediction Using the Calibrated Modelsupporting

confidence: 91%

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

Mahmoudi

Tapia

Karayagiz

et al. 2018

Integr Mater Manuf Innov

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“…Meanwhile, laser absorption simulations such as the Ray tracing model may help to predict the absorption behaviour of various powders processed under SLM but were still unable to provide accurate measurements for powder materials with high particle surface roughness and oxidised skins [123][124][125]. For validation purposes, a simple calorimetry method was recently proposed by [126] to carry out direct absorptivity measurements on powder deposited in a similar manner to SLM systems with the consideration of other heat transfer effects. Powder thermal absorptivity was determined based on temperature changes over a powder-coated disk with known dimensions, under a uniform exposure of 1µm laser irradiation (Refer to Figure 24).…”

Section: Powder Thermal Propertiesmentioning

confidence: 99%

An overview of powder granulometry on feedstock and part performance in the selective laser melting process

Tan

Wong

Dalgarno

2017

Additive Manufacturing

207

154

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“…Indeed, the solidification of the exposed powder bed is influenced by the heat input. As highlighted by the work of Rubenchik et al, [13] the absorptivity of 316L stainless steel powder is about 60 pct; thus, a large fraction of the energy is being reflected. The absorbed energy is then transferred through radiation from the top surface, convection to the atmosphere, conduction to the powder bed, the solidified material, and the baseplate.…”

Section: Introductionmentioning

confidence: 97%

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

Pauzon

Leicht

Klement

et al. 2020

Metall Mater Trans A

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The development of the laser powder bed fusion (L-PBF) process to increase its robustness and productivity is challenged by ambitious design optimizations, such as thin wall structures. In this study, in addition to the effect of commonly used gases as Ar and N2, increased laser scanning speed and new process gases, such as helium, were successfully implemented. This implementation allowed to build 316L stainless steel components with thin walls of 1 mm thickness with an enhanced build rate of 37 pct. The sample size effect and the surface roughness were held responsible for the reduction in strength (YS > 430 MPa) and elongation (EAB > 30 pct) for the 1 mm samples studied. Similar strength was achieved for all process gases. The increased scanning speed was accompanied by a more random texture, smaller cell size, and grain size factor along the building direction when compared to the material built with the standard laser parameters. Stronger preferential orientation 〈101〉 along the building direction was observed for material built with standard parameters. Finally, the use of helium as a process gas was successful and resulted in reduced cell size. This finding is promising for the future development of high strength 316L stainless steel built with high build rates.

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Direct measurements of temperature-dependent laser absorptivity of metal powders

Cited by 78 publications

References 8 publications

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

Multivariate Calibration and Experimental Validation of a 3D Finite Element Thermal Model for Laser Powder Bed Fusion Metal Additive Manufacturing

An overview of powder granulometry on feedstock and part performance in the selective laser melting process

Effect of the Process Gas and Scan Speed on the Properties and Productivity of Thin 316L Structures Produced by Laser-Powder Bed Fusion

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