The Marangoni Convection Effect on Melt Pool Formation during Selective Laser Melting Process

2021 ◽  
Vol 412 ◽  
pp. 107-114
Author(s):  
Samia Aggoune ◽  
Farida Hamadi ◽  
Karim Kheloufi ◽  
Toufik Tamsaout ◽  
El-Hachemi Amara ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Molten Pool ◽  
Marangoni Convection ◽  
Flow Behavior ◽  
Internal Flow ◽  
Melting Process ◽  
Heat Diffusion ◽  
Maximum Temperature ◽  
Laser Melting ◽  
Pool Shape

In order to predict the effect of the Marangoni convection and the morphology of melted stainless steel powder, during the selective laser melting (SLM) process, a transient three-dimensional numerical model is developed at the mesoscale. The evolution of the temperature and velocity fields’ is then studied. The initial powder bed distribution is obtained by the discrete element method (DEM) calculation, and the temperature distribution and the molten pool shape deformation are calculated and analyzed by the Ansys-Fluent commercial code. The molten pool shape is obtained by considering the influence of Marangoni convection on the internal flow behavior. The recoil force was not considered in our calculation. As main results, a slight deviation between the position of the maximum temperature of the molten pool and the center of the laser spot is observed. The direction of the heat diffusion is more likely to be horizontal and the flow centrifugal, which causes the melt track to be wide. Finally, the Marangoni convection is the main driver of the flow.

scholarly journals Numerical Simulation of Moving Heat Flux during Selective Laser Melting of AlSi25 Alloy Powder

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 877
Author(s):  
Cong Ma ◽  
Xianshun Wei ◽  
Biao Yan ◽  
Pengfei Yan
Keyword(s):  
Numerical Simulation ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Molten Pool ◽  
Laser Power ◽  
Scanning Speed ◽  
Powder Layer ◽  
Maximum Temperature ◽  
Three Dimensional Model ◽  
Laser Melting

A single-layer three-dimensional model was created to simulate multi-channel scanning of AlSi25 powder in selective laser melting (SLM) by the finite element method. Thermal behaviors of laser power and scanning speed in the procedure of SLM AlSi25 powder were studied. With the increase of laser power, the maximum temperature, size and cooling rate of the molten pool increase, while the scanning speed decreases. For an expected SLM process, a perfect molten pool can be generated using process parameters of laser power of 180 W and a scanning speed of 200 mm/s. The pool is greater than the width of the scanning interval, the depth of the molten pool is close to scan powder layer thickness, the temperature of the molten pool is higher than the melting point temperature of the powder and the parameters of the width and depth are the highest. To confirm the accuracy of the simulation results of forecasting excellent process parameters, the SLM experiment of forming AlSi25 powder was carried out. The surface morphology of the printed sample is intact without holes and defects, and a satisfactory metallurgical bond between adjacent scanning channels and adjacent scanning layers was achieved. Therefore, the development of numerical simulation in this paper provides an effective method to obtain the best process parameters, which can be used as a choice to further improve SLM process parameters. In the future, metallographic technology can also be implemented to obtain the width-to-depth ratio of the SLM sample molten pool, enhancing the connection between experiment and theory.

Microstructure Characterization of AlSi10Mg Fabricated by Selective Laser Melting Process

2018 ◽  
Vol 941 ◽  
pp. 1437-1442
Author(s):  
Takashi Maeshima ◽  
Keiichiro Oh-Ishi ◽  
Hiroaki Kadoura ◽  
Masashi Hara
Keyword(s):  
Selective Laser Melting ◽  
Molten Pool ◽  
Three Dimensional ◽  
Melting Process ◽  
Powder Layer ◽  
Base Temperature ◽  
Fish Scale ◽  
Laser Melting ◽  
Microstructure Observation ◽  
Three Dimensional Finite Element

Multi-scale microstructure observation and three dimensional finite element thermal analysis of AlSi10Mg alloy fabricated by selective laser melting (SLM) process were demonstrated in order to understand the microstructure formation process during SLM fabrication. The unique hierarchically microstructures were observed: (1) the “fish scale” microstructure corresponding to a part of molten pool consists of columnar and equiaxed grains and (2) these grains contain a substructure of α-Al surrounded by Si particles. It is revealed that a supersaturated Si concentration due to the predicted rapid cooling rate on the order of 106 oC/s. In addition, the base temperature during the fabrication increases gradually with some peak temperature of each laser path as the laser scan has proceeded on a powder layer. Although the thermal changes cause no melting of the AlSi10Mg except directly fused region by selective laser so called molten pool, those are capable of causing precipitation and/or clustering.

scholarly journals Effect of Selective Laser Melting Process Parameters on Microstructure and Properties of Co-Cr Alloy

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1546 ◽  
Author(s):  
Jian-Hong Wang ◽  
Jie Ren ◽  
Wei Liu ◽  
Xiao-Yu Wu ◽  
Ming-Xiang Gao ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Process Parameters ◽  
Molten Pool ◽  
Laser Energy ◽  
Melting Process ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
The Relationship ◽  
Cobalt Chromium Alloy

Due to the rapid melting and solidification mechanisms involved in selective laser melting (SLM), CoCrMo alloys fabricated by SLM differ from the cast form of the same alloy. In this study, the relationship between process parameters and the morphology and macromechanical properties of cobalt-chromium alloy micro-melting pools is discussed. By measuring the width and depth of the molten pool, a theoretical model of the molten pool is established, and the relationship between the laser power, the scanning speed, the scanning line spacing, and the morphology of the molten pool is determined. At the same time, this study discusses the relationship between laser energy and molding rate. Based on the above research, the optimal process for the laser melting of cobalt-chromium alloy in the selected area is obtained. These results will contribute to the development of biomedical CoCr alloys manufactured by SLM.

Thermal and molten pool model in selective laser melting process of Inconel 625

2018 ◽  
Vol 95 (9-12) ◽  
pp. 3977-3984 ◽  
Author(s):  
Erdem Kundakcıoğlu ◽  
Ismail Lazoglu ◽  
Özgür Poyraz ◽  
Evren Yasa ◽  
Nuri Cizicioğlu
Keyword(s):  
Selective Laser Melting ◽  
Molten Pool ◽  
Melting Process ◽  
Inconel 625 ◽  
Laser Melting ◽  
Selective Laser Melting Process ◽  
Pool Model

Three-Dimensional Temperature Gradient Mechanism in Selective Laser Melting of Ti-6Al-4V

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
C. H. Fu ◽  
Y. B. Guo
Keyword(s):  
Temperature Gradient ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Three Dimensional ◽  
Melting Process ◽  
Layer By Layer ◽  
Laser Melting ◽  
Transient Nature ◽  
Melting Pool ◽  
Three Dimensional Finite Element

Selective laser melting (SLM) is widely used in making three-dimensional functional parts layer by layer. Temperature magnitude and history during SLM directly determine the molten pool dimensions and surface integrity. However, due to the transient nature and small size of the molten pool, the temperature gradient and the molten pool size are challenging to measure and control. A three-dimensional finite element (FE) simulation model has been developed to simulate multilayer deposition of Ti-6Al-4 V in SLM. A physics-based layer buildup approach coupled with a surface moving heat flux was incorporated into the modeling process. The melting pool shape and dimensions were predicted and experimentally validated. Temperature gradient and thermal history in the multilayer buildup process was also obtained. Furthermore, the influences of process parameters and materials on the melting process were evaluated.

scholarly journals Improving surface quality in selective laser melting based tool making

2021 ◽  
Author(s):  
Filippo Simoni ◽  
Andrea Huxol ◽  
Franz-Josef Villmer
Keyword(s):  
Surface Roughness ◽  
Additive Manufacturing ◽  
Surface Quality ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Laser Remelting ◽  
Laser Melting ◽  
Great Cost ◽  
Starting Point ◽  
Processing Techniques

AbstractIn the last years, Additive Manufacturing, thanks to its capability of continuous improvements in performance and cost-efficiency, was able to partly replace and redefine well-established manufacturing processes. This research is based on the idea to achieve great cost and operational benefits especially in the field of tool making for injection molding by combining traditional and additive manufacturing in one process chain. Special attention is given to the surface quality in terms of surface roughness and its optimization directly in the Selective Laser Melting process. This article presents the possibility for a remelting process of the SLM parts as a way to optimize the surfaces of the produced parts. The influence of laser remelting on the surface roughness of the parts is analyzed while varying machine parameters like laser power and scan settings. Laser remelting with optimized parameter settings considerably improves the surface quality of SLM parts and is a great starting point for further post-processing techniques, which require a low initial value of surface roughness.

scholarly journals Fabrication of Mesh Patterns Using a Selective Laser-Melting Process

2019 ◽  
Vol 9 (9) ◽  
pp. 1922 ◽  
Author(s):  
Tae Woo Hwang ◽  
Young Yun Woo ◽  
Sang Wook Han ◽  
Young Hoon Moon
Keyword(s):  
Selective Laser Melting ◽  
Laser Scanning ◽  
Dimensional Accuracy ◽  
Base Plate ◽  
Steel Powder ◽  
Melting Process ◽  
304 Stainless Steel ◽  
Process Conditions ◽  
Laser Melting ◽  
Metal Mesh

The selective laser-melting (SLM) process can be applied to the additive building of complex metal parts using melting metal powder with laser scanning. A metal mesh is a common type of metal screen consisting of parallel rows and intersecting columns. It is widely used in the agricultural, industrial, transportation, and machine protection sectors. This study investigated the fabrication of parts containing a mesh pattern from the SLM of AISI 304 stainless steel powder. The formation of a mesh pattern has a strong potential to increase the functionality and cost-effectiveness of the SLM process. To fabricate a single-layered thin mesh pattern, laser layering has been conducted on a copper base plate. The high thermal conductivity of copper allows heat to pass through it quickly, and prevents the adhesion of a thin laser-melted layer. The effects of the process conditions such as the laser scan speed and scanning path on the size and dimensional accuracy of the fabricated mesh patterns were characterized. As the analysis results indicate, a part with a mesh pattern was successfully obtained, and the application of the proposed method was shown to be feasible with a high degree of reliability.

scholarly journals Selective Laser Melting Process of Al–Based Pyramidal Horns for the W-Band: Fabrication and Testing

2021 ◽  
Author(s):  
L. Lamagna ◽  
A. Paiella ◽  
S. Masi ◽  
L. Bottini ◽  
A. Boschetto ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
High Surface ◽  
Melting Process ◽  
Horn Antenna ◽  
Post Processing ◽  
Laser Melting ◽  
Performance Impact ◽  
Horn Antennas ◽  
Sand Blasting ◽  
W Band

AbstractIn the context of exploring the possibility of using Al-powder Selective Laser Melting to fabricate horn antennas for astronomical applications at millimeter wavelengths, we describe the design, the fabrication, the mechanical characterization, and the electromagnetic performance of additive manufactured horn antennas for the W-band. Our aim, in particular, is to evaluate the performance impact of two basic kinds of surface post-processing (manual grinding and sand-blasting) to deal with the well-known issue of high surface roughness in 3D printed devices. We performed comparative tests of co-polar and cross-polar angular response across the whole W-band, assuming a commercially available rectangular horn antenna as a reference. Based on gain and directivity measurements of the manufactured samples, we find decibel-level detectable deviations from the behavior of the reference horn antenna, and marginal evidence of performance degradation at the top edge of the W-band. We conclude that both kinds of post-processing allow achieving good performance for the W-band, but the higher reliability and uniformity of the sand-blasting post-process encourage exploring similar techniques for further development of aluminum devices at these frequencies.

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