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.

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.

Inverse Thermal Analysis of Melting Pool in Selective Laser Melting Process

2015 ◽  
Vol 651-653 ◽  
pp. 1519-1524 ◽  
Author(s):  
Laurent van Belle ◽  
Alban Agazzi
Keyword(s):  
Heat Source ◽  
Residual Stresses ◽  
Selective Laser Melting ◽  
Selective Laser Sintering ◽  
Solid Material ◽  
Melting Process ◽  
Layer By Layer ◽  
Laser Melting ◽  
Mechanical Modelling ◽  
Melting Pool

The Selective Laser Melting (SLM) process of metallic powder is an additive technology. It allows the production of complex-shaped parts which are difficult to obtain by conventional methods. The principle is similar to Selective Laser Sintering (SLS) process: it consists, from an initial CAD model, to create the desired part layer by layer. The laser scans a powder bed of 40 μm thick. The irradiated powder is instantly melted and becomes a solid material when the laser moves away. A new layer of powder is left and the laser starts a new cycle of scanning. The sudden and intense phase changing involves high thermal gradients which induce contraction and expansion cycles in the part. These cycles results in irreversible plastic strains. The presence of residual stresses in the manufactured part can damage the mechanical properties, such as the fatigue life. This study focuses on the thermal and mechanical modelling of the SLM process. One of the key points of the mechanical modelling is the determination of the heat source generated by the laser in order to predict residual stresses. This work is divided in three parts. In a first part, an experimental protocol is established in order to measure the temperature variation during the process. In the second part, a thermal model of the process is proposed. Finally, an inverse method to determine the power and the shape of the heat source is developed. Experimental and computational results are fitted. The influence of several geometries of the heat source is investigated.

scholarly journals Analytical Modeling of Three-Dimensional Temperature Distribution of Selective Laser Melting of Ti-6Al-4V

2018 ◽  
Author(s):  
Jinqiang Ning ◽  
Steven Y. Liang
Keyword(s):  
Temperature Distribution ◽  
Selective Laser Melting ◽  
Molten Pool ◽  
Three Dimensional ◽  
Analytical Models ◽  
Process Conditions ◽  
Metallic Materials ◽  
Laser Melting ◽  
Metallic Additive ◽  
Complex Parts

Selective laser melting (SLM) is one of the widely used techniques in metallic additive manufacturing, in which high-density laser powder is utilized to selectively melting layers of powders to create geometrically complex parts. Temperature distribution and molten pool geometry directly determine the balling effect, and concentrated balling phenomenon significantly deteriorates surface integrity and mechanical properties of the part. Finite element models have been developed to predict temperature distribution and molten pool geometry, but they were computationally expensive. In this paper, the three-dimensional temperature distributions are predicted by analytical models using point moving heat source and semi-ellipsoidal moving source respectively. The molten pool dimensions under various process conditions are obtained from the three-dimensional temperature predictions and experimentally validated. Ti-6Al-4V alloy is chosen for the investigation. Good agreements between the predictions and the measurements are observed. The presented models are also suitable for other metallic materials in the SLM process.

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.

scholarly journals Visualization of the process of selective laser melting

2019 ◽  
Author(s):  
Андрей Молотков ◽  
Andrey Molotkov ◽  
Ольга Третьякова ◽  
Ol'ga Tret'yakova
Keyword(s):  
Selective Laser Melting ◽  
New Technology ◽  
Three Dimensional ◽  
Melting Process ◽  
Laser Fusion ◽  
Technological Parameters ◽  
Laser Melting ◽  
Advantages And Disadvantages ◽  
Big Picture ◽  
Level Of Training

This paper deals with the visualization of the previously simulated by the authors selective laser melting process in order to simplify the analysis of the results and the selection of technological parameters of the additive production unit. The article presents two possible approaches for visualization of the selective laser fusion process and supported functions which simplify the work and research in the framework of the new technology. The implemented approaches will reduce the requirements for the level of training of specialists working on Russian-made equipment. In the two-dimensional visualization mode, the emphasis is on the possibility of a more detailed study of the process. In a three-dimensional there is the ability of the broader scope and to see the big picture. Several implemented principles of geometry simplification for visual representation are considered. The advantages and disadvantages of the work done and the results obtained are presented.

Modelling of Turbulent Transport in Laser Melt Pools

2003 ◽  
Author(s):  
Nilanjan Chakraborty ◽  
Suman Chakraborty
Keyword(s):  
Phase Change ◽  
Thermal History ◽  
Molten Pool ◽  
Turbulent Transport ◽  
Three Dimensional ◽  
Melting Process ◽  
Work Piece ◽  
Laser Melting ◽  
History Of ◽  
Solid Liquid Interface

In this paper, we present a modified k-ε model capable of addressing turbulent molten metal-pool convection in the presence of a continuously evolving phase-change interface during a laser melting process. The phase change aspects of the present problem are addressed using a modified enthalpy-porosity technique. The k-ε model is suitably modified to account for the morphology of the solid-liquid interface. A three-dimensional mathematical model is subsequently utilised to simulate a typical laser melting process with high power, where effects of turbulent transport can actually be realised. In order to investigate these effects on laser molten pool convection, simulations with laminar transport and turbulent transport are carried out for same problem parameters. Finally, results of the simulation using the present turbulence model are compared with the results of laminar simulation with same problem parameters. Significant effects of turbulent transport on penetration and the geometrical features of the molten pool are observed which is an outcome of the thermal history of the pool. The thermal history in turn determines the microstructure of the work piece, which finally governs the mechanical properties of the work piece.

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
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