Thermo-Fluid-Dynamic Modeling of the Melt Pool during Selective Laser Melting for AZ91D Magnesium Alloy

Shen, Hongyao; Yan, Jinwen; Niu, Xiaomiao

doi:10.3390/ma13184157

Cited by 27 publications

(18 citation statements)

References 46 publications

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“…In the application aspect, Zhu et al [ 26 ] put forward two optimization-based methodologies to calibrate material parameters for the application of AM60B magnesium alloy material model to structure component crush analysis. A three-dimensional finite element model (FEM) was established by Shen et al [ 27 ] to simulate the temperature distribution, flow activity, and deformation of the melt pool of selective laser melting (SLM) AZ91D magnesium alloy powder. Samuha et al [ 28 ] improved formability for the commercial magnesium AZ80 alloy through the application of the high-rate electromagnetic forming (EMF) technique.…”

Section: Introductionmentioning

confidence: 99%

Material Model Development of Magnesium Alloy and Its Strength Evaluation

Huang

et al. 2021

Materials

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A new material model of magnesium alloys, combining both Hill’48 yield function and Cazacu’06 yield function, was developed and programmed into LS-DYNA using user subroutine, in which both slip dominant and twinning/untwinning dominant hardening phenomena were included. First, a cyclic load test was performed, and its finite element analysis was carried out to verify the new material model. Then, the deformation behaviors of the magnesium crash box subjected to the compressive impact loading were investigated using the developed material model. Compared with the experimental results, the new material model accurately predicted the deformation characteristics of magnesium alloy parts. Additionally, the effect of the thickness distribution, initial deflection and contact friction coefficient in simulation models on deformation behaviors were investigated using this validated material model.

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Section: Introductionmentioning

confidence: 99%

Material Model Development of Magnesium Alloy and Its Strength Evaluation

Huang

et al. 2021

Materials

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“…We compare cooling rate estimates from our simulations with the cooling rates estimated from experimental data of the LPBF process that were obtained from Bertsch et al [57]. Further, we also compare our simulation results with the corresponding material temperature distribution and meltpool velocity values obtained from numerical modeling data in Shen et al [58].…”

Section: Experimental and Numerical Validationmentioning

confidence: 77%

A Numerical Investigation of Dimensionless Numbers Characterizing Meltpool Morphology of the Laser Powder Bed Fusion Process

Bhagat¹,

Rudraraju²

2022

Preprint

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Microstructure evolution in metal additive manufacturing (AM) is a complex multi-physics and multi-scale problem. Understanding the impact of AM process conditions on microstructure evolution and the resulting mechanical properties of the printed part is an area of active research. In this context, high-fidelity numerical modeling of the AM process at various relevant length-scales has been finding favor. At the meltpool scale, the thermo-fluidic governing equations have been extensively modeled to understand the meltpool conditions and thermal gradients. In many phenomena governed by partial differential equations, dimensional analysis and identification of important dimensionless numbers can provide significant insights into the process dynamics. Hence, the use of dimensionless numbers to understand the complex multiphysics interactions active during metal AM is also gaining traction. In this context, we present a novel strategy using dimensional analysis and the least-squares regression approach, in conjunction with physics-based insights, to investigate the thermo-fluidic governing equations of the Laser Powder Bed Fusion AM process. Through this approach, we identify important dimensionless quantities influencing meltpool morphology. The governing equations are solved using the Finite Element Method, and the model predictions are validated by comparing with experimentally estimated cooling rates, and with numerical results from the literature. We then present our dimensional analysis and define an important dimensionless quantity - interpreted as a measure of heat absorbed by the powdered material and the resulting meltpool. We then use this dimensionless measure of heat absorbed, along with classical dimensionless quantities relevant to the thermo-fluidic governing equations, to investigate advective transport in the meltpool for different metal alloys. This understanding helps us characterize the meltpool aspect ratio and volume in terms of the Marangoni, and Stefan numbers. Further, we study the variations of thermal gradients and the solidification cooling rate using this framework and examine the effect of the Peclet number on the microstructure of the solidified meltpool region.

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“…The keyhole effect can also be used to explain the relative density difference between Group A and Group B at a high energy density input. Zhao et al (2020) and Shen et al (2020) analyzed the influence of different laser powers and scanning speeds on the melt flow rate under the same energy density through simulation, and they concluded that the laser power has a greater influence. That is, under the same energy density, a higher laser power can cause a stronger melt flow and cause the keyhole wall to collapse more easily and produce more pores.…”

Section: Discussionmentioning

confidence: 99%

“…At the same time, the melt in the molten pool flows because of the Marangoni effect, which may cause some keyhole walls to collapse and form pores. The Marangoni effect is a phenomenon in which the melt flows because of the surface tension gradient caused by the temperature gradient on the surface of the molten pool (Shen et al , 2020). On the other hand, with the increase in the energy input, the flow of the melt caused by the Marangoni effect is strengthened, resulting in a rugged build surface on the component.…”

Section: Discussionmentioning

confidence: 99%

Effects of the process parameters on the formability and properties of Ni54(at.%) Ti alloys prepared by laser powder bed fusion

Shen

2022

RPJ

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Purpose The purpose of this paper is to supplement and upgrade existing research on LPBF of NiTi alloys. Laser powder bed fusion (LPBF) is a promising method for fabricating nickel–titanium (Ni–Ti) alloys. It is well known that the energy density is mainly adjusted through the scanning speed and laser power. Nevertheless, there is lack in research on the effects of separately adjusting the scanning speed and laser power on the properties of the final Ni–Ti components. On the other hand, although Ni-rich Ni–Ti alloys [such as Ni54(at.%)Ti] have great potential in structural applications because of their high hardness and good shape stability, at present, there are few studies focusing on this grade of Ni–Ti alloy. Design/methodology/approach In this work, the energy density was adjusted by changing the laser power and scanning speed separately, and the corresponding process parameters were used to fabricate Ni54(at.%)Ti alloys. The formability (including the relative density, impurity content, etc.) and tensile properties of the LPBF Ni54(at.%)Ti alloys fabricated with different combinations of process parameters were analyzed. Findings The effects of increasing the laser power and reducing the scanning speed on the properties of the LPBF Ni54(at.%)Ti alloys and the property differences between components manufactured with different combinations of laser power and scanning speed under the same energy density were analyzed. The optimal process parameters were selected to fabricate the components that achieved the highest ultimate tensile strength of 537 MPa, a high relative density of 98.23%, a relatively low impurity content (0.073 Wt.% of carbon and 0.06 Wt.% of oxygen) and an ideal pseudoelasticity (95% recovery rate loaded at 300 MPa). Originality/value The effects of increasing the laser power and reducing the scanning speed on the properties of LPBF Ni54(at.%)Ti alloys were studied in this paper. This work is an upgrade and supplement to the existing research on fabricating Ni-rich Ni–Ti alloys by the LPBF method.

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Thermo-Fluid-Dynamic Modeling of the Melt Pool during Selective Laser Melting for AZ91D Magnesium Alloy

Cited by 27 publications

References 46 publications

Material Model Development of Magnesium Alloy and Its Strength Evaluation

Material Model Development of Magnesium Alloy and Its Strength Evaluation

A Numerical Investigation of Dimensionless Numbers Characterizing Meltpool Morphology of the Laser Powder Bed Fusion Process

Effects of the process parameters on the formability and properties of Ni54(at.%) Ti alloys prepared by laser powder bed fusion

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