Numerical modeling of thermal anisotropy on a selective laser melting process

Trejos, Juan Daniel; Reyes, Luis A.; Garza, Carlos; Zambrano‐Robledo, Patricia del Carmen; López-Botello, Omar

doi:10.1108/rpj-02-2020-0032

Cited by 9 publications

(11 citation statements)

References 30 publications

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“…the powder bed was a homogeneous medium with equivalent effective thermal and optical properties; and the effects of Marangoni convection on the evolution of the melt pool were taken into account using a simple anisotropic thermal conductivity term (Safdar et al, 2013;Trejos et al, 2020).…”

Section: Heat Transfer Simulation Model For Melt Pool Dimensionsmentioning

confidence: 99%

“…As described in Section 2.2, the effects of Marangoni convection on the creation of the melt pool were approximated using the anisotropic thermal conductivity method proposed in (Trejos et al, 2020). Accordingly, the enhancement factors of the thermal conductivity in l xx , l yy and l zz were evaluated as follows:…”

Section: Heat Transfer Simulation Model For Melt Pool Dimensionsmentioning

confidence: 99%

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Multi-scale simulation approach for identifying optimal parameters for fabrication ofhigh-density Inconel 718 parts using selective laser melting

Tran

et al. 2021

RPJ

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Purpose Depending on an experimental approach to find optimal parameters for producing fully dense (relative density > 99%) Inconel 718 (IN718) components in the selective laser melting (SLM) process is expensive and offers no guarantee of success. Accordingly, this study aims to propose a multi-scale simulation framework to guide the choice of processing parameters in a more pragmatic manner. Design/methodology/approach In the proposed approach, a powder layer, ray tracing and heat transfer simulation models are used to calculate the melt pool dimensions and evaporation volume corresponding to a small number of laser power and scanning speed conditions within the input design space. A layer-heating model is then used to determine the inter-layer idle time required to maximize the temperature convergence rate of the solidified layer beneath the power bed. The simulation results are used to train surrogate models to construct SLM process maps for 3,600 pairs of the laser power and scanning speed within the input design space given three different values of the underlying solidified layer temperature (i.e., 353 K, 673 K and 873 K). The ideal selection of laser power and scanning speed of each process map is chosen based on four quality-related criteria listed as follows: without the appearance of key-hole melting; an evaporation volume less than the volume of the d90 powder particles; ensuring the stability of single scan tracks; and avoiding a weak contact between the melt pool and substrate. Finally, the optimal laser power and scanning speed parameters for the SLM process are determined by superimposing the optimal regions of the individual process maps. Findings The feasibility of the proposed approach is demonstrated by fabricating IN718 test specimens using the optimal processing conditions identified by the simulation framework. It is shown that the maximum density of the fabricated parts is 99.94%, while the average density is 99.88% and the standard deviation is less than 0.05%. Originality/value The present study proposed a multi-scale simulation model which can efficiently predict the optimal processing conditions for producing fully dense components in the SLM process. If the geometry of the three-dimensional printed part is changed or the machine and powder material is altered, users can use the proposed method for predicting the processing conditions that can produce the high-density part.

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Section: Heat Transfer Simulation Model For Melt Pool Dimensionsmentioning

confidence: 99%

Section: Heat Transfer Simulation Model For Melt Pool Dimensionsmentioning

confidence: 99%

Multi-scale simulation approach for identifying optimal parameters for fabrication ofhigh-density Inconel 718 parts using selective laser melting

Tran

et al. 2021

RPJ

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“…The single scan-track simulations were implemented in COMSOL Multi-physics software version 5.3. To simplify the simulation process (while preserving the accuracy), the following assumptions were made: the IN713LC powder bed was homogeneous, isotropic and continuous; the volume shrinkage of the powder layer during solidification was sufficiently small to be ignored; the moving laser heat source had a Gaussian distribution and irradiated the powder bed directly; the effect of Marangoni convection on the melt pool dimension is taken into account by using the anisotropic enhanced thermal conductivity approach proposed in Safdar et al (2013) and Trejos et al (2020); and the coefficient of convection between the powder bed and the environment was constant and the radiation effect was ignored. Given these assumptions, the governing equation for the 3D heat transfer within the powder bed was formulated as follows (Roberts et al, 2009):…”

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

Systematic approach for reducing micro-crack formation in Inconel 713LC components fabricated by laser powder bed fusion

Wang

Tran

et al. 2021

RPJ

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Purpose For high crack-susceptibility materials such as Inconel 713LC (IN713LC) nickel alloy, fabricating crack-free components using the laser powder bed fusion (LPBF) technique represents a significant challenge because of the complex interactions between the effects of the main processing parameters, namely, the laser power and scanning speed. Accordingly, this study aims to build up a methodology which combines simulation model and experimental approach to fabricate high-density (>99.9%) IN713LC components using LPBF process. Design/methodology/approach The present study commences by performing three-dimensional (3D) heat transfer finite element simulations to predict the LPBF outcome (e.g. melt pool depth, temperature and mushy zone extent) for 33 representative sample points chosen within the laser power and scanning speed design space. The simulation results are used to train a surrogate model to predict the LPBF result for any combination of the processing conditions within the design space. Then, experimental trials were performed to choose the proper hatching space and also to define the high crack susceptibility criterion. The process map is then filtered in accordance with five quality criteria, namely, avoiding the keyhole phenomenon, improving the adhesion between the melt pool and the substrate, ensuring single-scan-track stability, avoiding excessive melt pool evaporation and suppressing the formation of micro-cracks, to determine the region of the process map which improves the relative density of the IN713LC component and minimizes the micro-cracks. The optimal processing conditions are used to fabricate IN713LC specimens for tensile testing purposes. Findings The optimal processing conditions predicted by simulation model are used to fabricate IN713LC specimens for tensile testing purposes. Experimental results show that the tensile strength and elongation of 3D-printed IN713LC tensile bar is higher than those of tensile bar made by casting. The yield strength of 791 MPa, ultimate strength of 995 MPa, elongation of 12%, and relative density of 99.94% are achieved. Originality/value The present study proposed a systematic methodology to find the processing conditions that are able to minimize the formation of micro-crack and improve the density of the high crack susceptivity metal material in LPBF process.

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“…To minimize the number of experiments, the Taguchi DOE method was used. This method is typically used for designing the experiments and optimize the functional parameters of the experimental tests (Singh et al, 2019;Trejos et al, 2020;Camargo et al, 2019;Joguet et al, 2016;Saad et al, 2019). The application of this method can significantly reduce the cost of experiments in the 3D printing research field (Nomani et al, 2020).…”

Section: Design Of Experimentsmentioning

confidence: 99%

Experimental study on tensile strength of copper microparticles filled polymer composites printed by fused deposition modelling process

Adibi

Hashemi

2021

RPJ

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Purpose The purpose of this paper is to investigate the variables of the fused deposition modelling (FDM) process and improve their effect on the mechanical properties of acrylonitrile butadiene styrene (ABS) components reinforced with copper microparticles. Design/methodology/approach In the experimental approach, after drying the ABS granule, it was mixed with copper microparticles (at concentrations of 5%, 8% and 10%) in a single screw extruder to fabricate pure ABS and composite filaments. Then, by making the components by the FDM process, the tensile strength of the parts was determined through tensile strength tests. Taguchi DOE method was used to design the experiments in which nozzle temperature, filling pattern and layer thickness were the design variables. The analysis of variance (ANOVA) and signal-to-noise analysis were conducted to determine the effectiveness of each FDM process parameter on the ultimate tensile strength of printed samples. Following that, the main effect analysis was used to optimize each process parameter for pure ABS and its composite at different copper contents. Findings The study allows the layer thickness and filling pattern had the highest effects on the ultimate tensile strength of the printed materials (pure and composite) in the FDM process. Moreover, the results show that the ultimate tensile strength of the ABS composite containing 5% copper was nearly 12.3% higher than the pure ABS part. According to validation tests, the maximum error of experiments was about 0.96%. Originality/value In this paper, the effect of copper microparticles (as filling agent) was investigated on the ultimate tensile strength of printed ABS material during the FDM process.

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Numerical modeling of thermal anisotropy on a selective laser melting process

Cited by 9 publications

References 30 publications

Multi-scale simulation approach for identifying optimal parameters for fabrication ofhigh-density Inconel 718 parts using selective laser melting

Multi-scale simulation approach for identifying optimal parameters for fabrication ofhigh-density Inconel 718 parts using selective laser melting

Systematic approach for reducing micro-crack formation in Inconel 713LC components fabricated by laser powder bed fusion

Experimental study on tensile strength of copper microparticles filled polymer composites printed by fused deposition modelling process

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