Analysis of Scattering and Absorption Characteristics of Metal Powder Layer for Selective Laser Sintering

Tran, Hong-Chuong; Lo, Yu-Lung; Huang, Min-Hao

doi:10.1109/tmech.2017.2705090

Cited by 46 publications

(27 citation statements)

References 20 publications

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“…The model considers both the temperature-dependent properties of IN713LC and the powder bed melting process. The volumetric heat source for the transient 3D heat transfer FE model can be formulated as (Tran and Lo, 2018;Tran et al, 2017)…”

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

“…The term A(z) in equation ( 1) describes the distribution of absorbed laser energy through the depth of metal powder layer. Notably, the details of the process of constructing the absorption profile A(z) can be found in our previous studies (Tran and Lo, 2018;Tran et al, 2017). The single scan-track simulations were implemented in COMSOL Multi-physics software version 5.3.…”

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

“…where t machine is the distance by which the build plate drops between each layer; p is the packing density of the powder bed; and t real is the actual powder layer thickness in the L-PBF process. In the experiment, the drop-down distance of build plate is set as 20 m m and the packing density of the powder bed is calculated as 0.5 [notably, the simulation model of the present group in previous study (Tran and Lo, 2018;Tran et al, 2017) was used to calculate the packing density]. Thus, from equation ( 3), the real powder layer thickness is equal to 40 mm.…”

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

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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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Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

Section: Heat Transfer and Powder Bed Modelingmentioning

confidence: 99%

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

Wang

Tran

et al. 2021

RPJ

Self Cite

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“…Density of the additively manufactured part built via L-PBF has a crucial impact on mechanical properties of the fabricated component. An approach to identify processing parameters for producing high-density parts was employed to select the processing conditions, as described in the previous studies [31][32][33][34]. Tong Tai AM250 selective laser melting (SLM) machine (Kaohsiung, Taiwan), equipped with a 50-400 W YAG laser with the laser spot size of D4sigma = 54 µm, was used to fabricate rectangular bar shape samples with dimensions of 10 × 5 × 5 mm 3 .…”

Section: Build Processmentioning

confidence: 99%

Analytical Modeling of Residual Stress in Laser Powder Bed Fusion Considering Part’s Boundary Condition

Mirkoohi

Tran

et al. 2020

Crystals

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Rapid and accurate prediction of residual stress in metal additive manufacturing processes is of great importance to guarantee the quality of the fabricated part to be used in a mission-critical application in the aerospace, automotive, and medical industries. Experimentations and numerical modeling of residual stress however are valuable but expensive and time-consuming. Thus, a fully coupled thermomechanical analytical model is proposed to predict residual stress of the additively manufactured parts rapidly and accurately. A moving point heat source approach is used to predict the temperature field by considering the effects of scan strategies, heat loss at part’s boundaries, and energy needed for solid-state phase transformation. Due to the high-temperature gradient in this process, the part experiences a high amount of thermal stress which may exceed the yield strength of the material. The thermal stress is obtained using Green’s function of stresses due to the point body load. The Johnson–Cook flow stress model is used to predict the yield surface of the part under repeated heating and cooling. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is precited using incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. Experimental measurement of residual stress was conducted using X-ray diffraction on the fabricated IN718 built via laser powder bed fusion to validate the proposed model.

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“…Density of the additively manufactured part built via L-PBF has a crucial impact on mechanical properties of the fabricated component. An approach to identify processing parameters for producing high-density parts is employed to select the processing conditions as described in the previous studies [33][34][35][36]. The processing conditions used to fabricate high-density samples for measuring the residual stress are listed in Table 2.…”

Section: Prediction Of Johnson-cook (J-c) Parametersmentioning

confidence: 99%

Analytical Modeling of Residual Stress in Laser Powder Bed Fusion

Mirkoohi¹,

Ning²,

Liang³

2020

Preprint

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Rapid and accurate prediction of residual stress in metal additive manufacturing processes is of great importance to guarantee the quality of the fabricated part to be used in a mission-critical application in the aerospace and automotive industries. Experimentation and numerical modeling are valuable tools for measuring and predicting the residual stress; however, to-date conducting experimentation and numerical modeling is expensive and time-consuming. Thus, herein, a physics-based thermomechanical analytical model is proposed to predict the residual stress of the additively manufactured part rapidly and accurately. A moving point heat source approach is used to predict the temperature field by considering the effects of scan strategies, heat loss, and energy needed for solid-state phase transformation. Due to the high temperature gradient in this process, part experiences a high amount of thermal stress following solidification which may exceed the yield strength of the material. The thermal stress is obtained using Green’s function of stresses due to the point body load. The Johnson-Cook flow stress model is used to predict the yield surface of the part under repeated heating and cooling. As a result of the cyclic heating and cooling and the fact that the material is yielded, the residual stress build-up is predicted based on incremental plasticity and kinematic hardening behavior of the metal according to the property of volume invariance in plastic deformation in coupling with the equilibrium and compatibility conditions. The computational methodology is realized with the laser powder fusion of maraging steel 350 as a material of example. The validation of the predictive models has been presented in terms of the comparison of predicted and measured scan-direction and build-direction residual stress distributions along depth of build under various process parameter combinations. Moreover, for the first time, the Jonson-Cook parameters of maraging steel 350 are predicted using analytical modeling of machining forces and non-linear optimization techniques.

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Analysis of Scattering and Absorption Characteristics of Metal Powder Layer for Selective Laser Sintering

Cited by 46 publications

References 20 publications

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

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

Analytical Modeling of Residual Stress in Laser Powder Bed Fusion Considering Part’s Boundary Condition

Analytical Modeling of Residual Stress in Laser Powder Bed Fusion

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