Development of 3D Finite Element Model for Predicting Process-Induced Defects in Additive Manufacturing by Selective Laser Melting (SLM)

2016 ◽  
Author(s):  
Bilal Hussain ◽  
A. Sherif El-Gizawy
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Thermal Stresses ◽  
Cost Effective ◽  
Element Model ◽  
Laser Melting ◽  
Two Phase ◽  
Free Process ◽  
Manufacturing Techniques

Selective Laser Melting (SLM) is one of the important Additive Manufacturing techniques for building functional products. Nevertheless, the absence of accurate models for predicting the SLM process behavior, delays development of cost effective and defects free process. This work presents a coupled thermo-mechanical numerical model to capture the two phase (solid-liquid) solidification melting phenomena that occur in the process. The proposed model will also predict the evolvement of process-induced properties and defects particularly residual stresses caused by temperature gradient and thermal stresses. CO2 or Nd:YAG laser beam can be used as a heat source with a Gaussian distribution for the laser beam energy.

Properties of Aluminium Alloys Produced by Selective Laser Melting

2016 ◽  
Vol 710 ◽  
pp. 83-88 ◽  
Author(s):  
Paola Bassani ◽  
Carlo Alberto Biffi ◽  
Riccardo Casati ◽  
Adrianni Zanatta Alarcon ◽  
Ausonio Tuissi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Aluminium Alloys ◽  
Al Alloys ◽  
Laser Melting ◽  
Microstructural Refinement ◽  
Manufacturing Techniques

Analysis of peculiar properties offered by Al alloys produced according to additive manufacturing techniques, specifically by Selective Laser Melting (SLM), is carried out. Two alloys are considered, derived by casting (AlSi10Mg) and by wrought (ENAW 2618) applications. The SLM processed samples are investigated considering their microstructural and mechanical properties after SLM and compared to cast and wrought counterparts. A strong microstructural refinement induced by SLM processing is observed for both alloys, resulting in excellent hardness properties. Investigation on integrity of samples revealed that small-size microvoids and unmelted regions could be present in SLM parts.

scholarly journals Selective Laser Melting process simulation of open lattice cellular materials

2018 ◽  
Vol 188 ◽  
pp. 03019
Author(s):  
George Lampeas
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Process Simulation ◽  
Melting Process ◽  
Element Model ◽  
Cellular Materials ◽  
Laser Melting ◽  
Simulation Methodology ◽  
Efficient Simulation ◽  
Present Simulation

In the present paper an efficient simulation of an Additive Manufacturing process is presented. The analysis is aiming to quantify the relations between process parameters and material characteristics. The methodology is demonstrated in the fabrication of an open-lattice Body- Centred-Cubic (BCC) cellular core, produced by means of the Additive Manufacturing Selective Laser Melting method. The results of the developed finite element model are compared to experimental results demonstrating a successful validation of the simulation methodology. The results of the present simulation can be used as input for the prediction of the mechanical properties of the cellular materials under investigation.

scholarly journals Power Density Distribution for Laser Additive Manufacturing (SLM): Potential, Fundamentals and Advanced Applications

Technologies ◽  
2018 ◽  
Vol 7 (1) ◽  
pp. 5 ◽  
Author(s):  
Alexander Metel ◽  
Michael Stebulyanin ◽  
Sergey Fedorov ◽  
Anna Okunkova
Keyword(s):  
Additive Manufacturing ◽  
Laser Beam ◽  
Density Distribution ◽  
Power Density ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Laser Additive Manufacturing ◽  
Power Density Distribution ◽  
Advanced Applications

Problems with the laser additive manufacturing of metal parts related to its low efficiency are known to hamper its development and application. The method of selective laser melting of metallic powders can be improved by the installation of an additional laser beam modulator. This allows one to control the power density distribution optically in the laser beam, which can influence the character of heat and mass transfer in a molten pool during processing. The modulator contributes alternative modes of laser beam: Gaussian, flat top (top hat), and donut (bagel). The study of its influence includes a mathematical description and theoretical characterization of the modes, high-speed video monitoring and optical diagnostics, characterization of processing and the physical phenomena of selective laser melting, geometric characterization of single tracks, optical microscopy, and a discussion of the obtained dependences of the main selective laser melting (SLM) parameters and the field of its optimization. The single tracks were produced using the advanced technique of porosity lowering. The parameters of the obtained samples are presented in the form of 3D graphs. The further outlook and advanced applications are discussed.

scholarly journals An Experimental Study on Micro-Milling of a Medical Grade Co-Cr-Mo Alloy Produced by Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2208 ◽  
Author(s):  
Gabriele Allegri ◽  
Alessandro Colpani ◽  
Paola Serena Ginestra ◽  
Aldo Attanasio
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Chip Thickness ◽  
Material Behavior ◽  
Micro Milling ◽  
Cobalt Chromium ◽  
Laser Melting ◽  
Chip Formation Mechanism ◽  
Manufacturing Techniques ◽  
Cobalt Chromium Molybdenum

Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys are very promising materials, in particular, in the biomedical field where their unique properties of biocompatibility and wear resistance can be exploited for surgery applications, prostheses, and many other medical devices. While Additive Manufacturing is a key technology in this field, micro-milling can be used for the creation of micro-scale details on the printed parts, not obtainable with Additive Manufacturing techniques. In particular, there is a lack of scientific research in the field of the fundamental material removal mechanisms involving micro-milling of Co-Cr-Mo alloys. Therefore, this paper presents a micro-milling characterization of Co-Cr-Mo samples produced by Additive Manufacturing with the Selective Laser Melting (SLM) technique. In particular, microchannels with different depths were made in order to evaluate the material behavior, including the chip formation mechanism, in micro-milling. In addition, the resulting surface roughness (Ra and Sa) and hardness were analyzed. Finally, the cutting forces were acquired and analyzed in order to ascertain the minimum uncut chip thickness for the material. The results of the characterization studies can be used as a basis for the identification of a machining window for micro-milling of biomedical grade cobalt-chromium-molybdenum (Co-Cr-Mo) alloys.

Processing of Ti Alloys by Additive Manufacturing: A Comparison of the Microstructures Obtained by Laser Cladding, Selective Laser Melting and Electron Beam Melting

2013 ◽  
Vol 765 ◽  
pp. 413-417 ◽  
Author(s):  
Sylvie Reginster ◽  
Anne Mertens ◽  
Hakan Paydas ◽  
Jerome Tchoufang Tchuindjang ◽  
Quentin Contrepois ◽  
...  
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Heat Flow ◽  
Selective Laser Melting ◽  
Electron Beam Melting ◽  
Laser Melting ◽  
Ti Alloys ◽  
Manufacturing Techniques ◽  
Microstructural Anisotropy ◽  
Ultrafast Cooling

In this study, samples of alloy Ti-6Al-4V have been processed by different additive manufacturing techniques in order to compare the resulting microstructure. In all three processes, ultrafast cooling gives rise to strongly out-of-equilibrium microstructures. However, the specific of the heat flow in each process lead to significant differences as far as the grains orientation and the resulting microstructural anisotropy are concerned.

scholarly journals Uncertainty assessment for measurement and simulation in selective laser melting: a case study of an aerospace part

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 96
Author(s):  
Giulio D'Emilia ◽  
Antoniomaria Di Ilio ◽  
Antonella Gaspari ◽  
Emanuela Natale ◽  
Antonios G. Stamopoulos
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Manufacturing Process ◽  
Thermal Stresses ◽  
Hybrid Approach ◽  
Coordinate Measuring Machine ◽  
Thermal Treatments ◽  
Laser Melting ◽  
Measuring Machine ◽  
Simulation Results

<p class="Abstract"><span lang="EN-US">In this work, the additive manufacturing process selective laser melting is analysed with the aim of realising a complex piece for aerospace applications. In particular, the effect of the manufacturing process and of the following thermal treatments on the dimensions of the workpiece is evaluated. The study is based on a hybrid approach including a simulation of the whole manufacturing process by advanced software packages and the dimensional measurements of the realised pieces taken by a coordinate measuring machine (CMM). The integrated use of simulation and measurements is carried out with the aim of validating the simulation results and of identifying the operational limits of both approaches; this analysis is based on metrological evaluation of the results of both the simulation and the tests, taking into account the uncertainty of the data. In addition, the main causes of uncertainty for the simulation activity and the experimental data have been identified, and the effects of some of them have also been experimentally evaluated. Based on the experimental validation, the simulation seems to predict the absolute displacement of the supports of the piece in a satisfactory way, while it is unable, in the actual configuration, to assess the conformity of the surface to its very tight shape tolerances. Conformity assessment of the surface should be carried out by CMM measurement. Integrated use of simulation and experimental results is expected to strongly improve the accuracy of simulation results for the effective and accurate design and control of the additive manufacturing process, including dimensional control and thermal treatments to mitigate induced thermal stresses.</span></p>

scholarly journals Selective Laser Melting: Materials and Applications

2020 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Konda Gokuldoss Prashanth
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
The Future ◽  
Manufacturing Techniques

Additive manufacturing (AM) is one of the emerging manufacturing techniques of immense engineering and scientific importance and is regarded as the technique of the future [...]

Optimization and analysis of porosity and roughness in selective laser melting 316L parts

2018 ◽  
Vol 1 (90) ◽  
pp. 5-15 ◽  
Author(s):  
M. Król ◽  
J. Mazurkiewicz ◽  
S. Żołnierczyk
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Laser Beam ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
316L Stainless Steel ◽  
Selective Laser Sintering ◽  
Technological Parameters ◽  
Laser Melting ◽  
Research Issues

Purpose: The investigations have been carried out on 316L stainless steel parts fabricated by Selective Laser Melting (SLM) technique. The study aimed to determine the effect of SLM parameters on porosity, hardness, and structure of 316L stainless steel. Design/methodology/approach: The analyses were conducted on 316L stainless steel parts by using AM125 SLM machine by Renishaw. The effects of the different manufacturing process parameters as power output, laser distance between the point’s melted metal powder during additive manufacturing as well as the orientation of the model relative to the laser beam and substrate on porosity, hardness, microstructure and roughness were analysed and optimised. Findings: The surface quality parts using 316L steel with the assumed parameters of the experiment depends on the process parameters used during the SLM technique as well as the orientation of formed walls of the model relative to the substrate and thus the laser beam. The lowest roughness of 316L SLM parts oriented perpendicularly to the substrate was found when 100 W and 20 μm the distance point was utilised. The lowest roughness for part oriented at 60° relatives to the substrate was observed when 125 W and the point distance 50 μm was employed. Practical implications: Stainless steel is one of the most popular materials used for selective laser sintering (SLM) processing to produce nearly fully dense components from 3D CAD models. Reduction of porosity is one of the critical research issues within the additive manufacturing technique SLM, since one of the major cost factors is the post-processing. Originality/value: This manuscript can serve as an aid in understanding the importance of technological parameters on quality and porosity of manufactured AM parts made by SLM technique.

scholarly journals Study of the Microstructure and Mechanical Properties Obtained by Laser Boost in SLM Process for the Ti-64 Alloy

2021 ◽  
Vol 1016 ◽  
pp. 1611-1617
Author(s):  
Caroline Widomski ◽  
Denis Solas ◽  
François Brisset ◽  
Anne Laure Helbert ◽  
Thierry Baudin ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Maximum Strength ◽  
Post Processing ◽  
Laser Melting ◽  
Melting Area ◽  
Microstructure And Mechanical Properties ◽  
Manufacturing Techniques ◽  
Complex Parts

Selective laser melting (SLM) is one of the new additive manufacturing techniques in which complex parts can be created directly by selectively melting layers of powder. If the productivity of the process is too fast, defects (porosity, partially melted powder, spatters …) are generated inside the fabricated parts and can deteriorate the mechanical properties of the product. A new Laser Boost strategy with a larger melting area and a productivity of 43.20 cm3/h has been compared to a Linear Classic strategy. Ti-64 alloy samples were elaborated with both strategies to study their influence on microstructure and mechanical properties. Laser Boost strategy leads to the formation of Ti-64 prior β grains that are larger than the Linear Classic strategy. Mechanical properties obtains are similar with both strategies with a maximum strength average around 1250MPa and an elongation at failure between 3 and 9%. A thermal post-processing by Hot Isostatic Pressure have been carried out on samples made by Laser Boost to increase the ductility of the material up to 15%.

Additive Manufacturing of Horizontal and 3D Functionally Graded 316L/Cu10Sn Components via Multiple Material Selective Laser Melting

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Chao Wei ◽  
Zhe Sun ◽  
Qian Chen ◽  
Zhu Liu ◽  
Lin Li
Keyword(s):  
Additive Manufacturing ◽  
Selective Laser Melting ◽  
Rapid Development ◽  
Functionally Graded ◽  
Smooth Transition ◽  
Gradual Transition ◽  
Laser Melting ◽  
Interesting Phenomenon ◽  
Graded Materials ◽  
Manufacturing Techniques

Production of functionally graded materials (FGMs, i.e., a gradual transition from one material to another) and components is challenging using conventional manufacturing techniques. Additive manufacturing (AM) provides a new opportunity for producing FGMs. However, current metal AM technologies including powder-bed fusion are limited to producing single material components or vertical FGM parts, i.e., a different material composition in different layers but not within the same layer, and in situ changing materials is challenging. In this paper, we demonstrate the fabrication of horizontal and 3D 316L/Cu10Sn components with FGM within the same layer and in different layers, via a proprietary multiple selective powder delivery array device incorporated into a selective laser melting system that allowed the deposition of up to six different materials point by point. The manufactured component macrostructure, microstructure, microhardness, and phases were examined. Smooth transition from one material to the other was realized. Also, an interesting phenomenon was found that the maximum hardness was at 50% 316L and 50% Cu10Sn. The work would open up a new opportunity for the manufacturing of true 3D functionally graded components using additive manufacturing and for the rapid development of new metal alloy systems.

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