scholarly journals A Computational Model of Melt Pool Morphology for Selective Laser Melting Process

2021 ◽  
Author(s):  
Kai Guo ◽  
Lihong Qiao ◽  
Zhicheng Huang ◽  
Nabil Anwer ◽  
Yuda Cao
Keyword(s):  
Computational Model ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Melting Process ◽  
Laser Melting ◽  
Synthetic Process ◽  
Part Geometry ◽  
Melt Pool ◽  
Proposed Model ◽  
High Consistency

Abstract Selective laser melting (SLM) is a promising metal additive manufacturing technology, which holds widespread applications in numerous fields. Unfortunately, it is arduous to predict the real SLM part geometry, which impedes its further development. While the morphology of melt pool, influenced and determined by process parameters, poses a crucial influence on the overall part geometry. Nonetheless, the association between process parameters and melt pool morphology is still unclear. Hence it is indispensable to explore relevant solution to address this issue. For this purpose, this paper proposes a new model to directly establish the mathematical relationship between process parameters and melt pool structure for SLM process. In this model, the status of melt pool is first qualitatively analyzed via the defined synthetic process index, and three types of melting states are differentiated including low melting, intermediate melting and high melting, which could cover different melt pool modes. Then, the computational model involving more physical mechanisms integrating mass conversion, heat exchange and temperature field is constructed. Melt pool critical geometries including the height, width, depth and length could be computed through the model. In order to validate the correctness of the proposed model, published experimental observations and existing models are compared. Calculation results from the proposed model show high consistency with the experimental samples and better accuracy than existing empirical models. Its applicability in melt pool classification and prediction is also verified, laying foundation for geometric simulation of SLM object which is successively shaped melt-pool by melt-pool.

Effect of selective laser melting process parameters on microstructural and mechanical properties of TiC–NiCr cermet

2020 ◽  
Vol 46 (18) ◽  
pp. 28749-28757 ◽  
Author(s):  
Atefeh Aramian ◽  
Zohreh Sadeghian ◽  
Seyed Mohammad Javad Razavi ◽  
Konda Gokuldoss Prashanth ◽  
Filippo Berto
Keyword(s):  
Mechanical Properties ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Melting Process ◽  
Laser Melting ◽  
Selective Laser Melting Process

scholarly journals The Analytical Prediction of Thermal Distribution and Defect Generation of Inconel 718 by Selective Laser Melting

2020 ◽  
Vol 10 (20) ◽  
pp. 7300 ◽  
Author(s):  
Huadong Yang ◽  
Zhen Li ◽  
Siqi Wang
Keyword(s):  
Selective Laser Melting ◽  
Process Parameters ◽  
Analytical Method ◽  
Inconel 718 ◽  
Analytical Prediction ◽  
Generation Process ◽  
Laser Melting ◽  
Internal Defects ◽  
Defect Generation ◽  
Melt Pool

In selective laser melting, the rapid change of the temperature field caused by the rapid movement of the laser causes the instability of the melt pool flow, resulting in a generation of defects, such as lack of fusion, keyholing and balling effect, which greatly affect the performance of parts. In order to fully understand the temperature distribution and defect generation process of selective laser melting (SLM), experimental research, numerical simulation and analytical methods are mainly applied. The analytical method is suitable for the determination of the optimal process parameters because it is simple and consumes fewer resources. In a simulation, the absorptivity of the material is usually regarded as a constant, but experimental studies have shown that absorptivity is related to temperature, laser power, scanning speed, layer thickness and other process parameters. Considering the dynamics of thermal physical properties of Inconel 718, an improved analytical method was proposed and successfully applied to thermal analysis and the prediction of melt pool size. By comparing with the results of finite element simulation, experiment and other analytical solutions, the ease of use and effectiveness of the method are verified. Based on the prediction of the melt pool and the criterion of internal defects, the combination of process parameters that produce internal defects is calculated, which will make it possible to quickly obtain ideal process parameters.

Numerical Investigation of Selective Laser Melting Process for 904L Stainless Steel

2012 ◽  
Author(s):  
Miranda Fateri ◽  
Andreas Gebhardt ◽  
Maziar Khosravi
Keyword(s):  
Heat Flux ◽  
Stainless Steel ◽  
Selective Laser Melting ◽  
Melting Process ◽  
Full Density ◽  
Laser Melting ◽  
Scanning Velocity ◽  
Selective Laser Melting Process ◽  
Fine Mesh ◽  
Melt Pool

Selective Laser Melting process (SLM) is an important manufacturing method for producing complex geometries which allows for creation of full density parts with similar properties as the bulk material without extensive post processing. In SLM process, laser power, beam focus diameter, and scanning velocity must be precisely set based on the material properties in order to produce dense parts. In this study, Finite Element Analysis (FEA) method is employed in order to simulate and analyze a single layer of 904L Stainless Steel. A three-dimensional transient thermal model of the SLM process based on phase change enthalpy, irradiation scattering, and heat conductivity of powder is developed. The laser beam is modeled as a moving heat flux on the surface of the layer using a fine mesh which allows for a variation of the shape and distribution of the beam. In this manner, various Gaussian distributions are investigated and compared against single and multi-element heat flux sources. The melt pool and temperature distribution in the part are numerically investigated in order to determine the effects of varying laser intensity, scanning velocity as well as preheating temperature. The results of the simulation are verified by comparing the melt pool width as a function of power and velocity against the experimentally obtained results. Lastly, 3D objects are fabricated with a SLM 50 Desktop machine using the acquired optimized process parameters.

Finite Element Thermal Analysis of Melt Pool in Selective Laser Melting Process

2018 ◽  
Author(s):  
Zhibo Luo ◽  
Yaoyao Fiona Zhao
Keyword(s):  
Heat Source ◽  
Selective Laser Melting ◽  
Computational Cost ◽  
Melting Process ◽  
Point Heat Source ◽  
Laser Melting ◽  
Line Heat Source ◽  
Powder Bed ◽  
Melt Pool ◽  
Gaussian Point

Selective laser melting is one of the powder bed fusion processes which fabricates a part through layer-wised method. Due to the ability to build a customized and complex part, selective laser melting process has been broadly studied in academic and applied in industry. However, rapidly changed thermal cycles and extremely high-temperature gradients among the melt pool induce a periodically changed thermal stress in solidified layers and finally result in a distorted part. Therefore, the temperature distribution in the melt pool and the size and shape of the melt pool directly determine the mechanical and geometrical property of final part. As experimental trial-and-error method takes a huge amount of cost, different numerical methods have been adopted to estimate the transient temperature and thermal stress distribution in the melt pool and powder bed. The most existing research utilizes the moving Gaussian point heat source to model the profile of the melt pool, which consumes a significant amount of computational cost and cannot be used to implement the part-level simulation. This research proposes a new line heat source to replace the moving point heat source. Some efforts are applied to reduce the computational cost. Specifically, a relatively large step size is used for the line heat source to reduce the number of time steps. In addition, a mesh refinement scheme is adopted to reduce the number of cells in each time step by refining the mesh close to the heat source and coarsening the mesh far away from it. On the other hand, efforts are implemented to increase the accuracy of the simulation result. Temperature-dependent material properties are considered in this FE framework. In addition, material transition among powder, liquid, and solid are incorporated in the developed FE framework. In this study, temperature simulation of one scanning track based on self-developed FE code is applied for Stainless Steel 316L. The simulation results show that the temperature distribution and history of melt pool within line heat source are comparable to that of the moving Gaussian point heat source. While the simulation time is reduced by more than two times depending on the length of line heat input. Therefore, this FE model can be used to numerically investigate the process parameters and help to control the quality of the final part.

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