Preliminary Testing of Temperature Measurements in Selective Laser Melting

2017 ◽  
Author(s):  
Bo Cheng ◽  
Stephen Cooke ◽  
Y. Kevin Chou
Keyword(s):  
Selective Laser Melting ◽  
Full Density ◽  
Beam Power ◽  
True Temperature ◽  
Width Ratio ◽  
Process Conditions ◽  
Thermal Imager ◽  
Laser Melting ◽  
Melt Pool ◽  
Length Width

Selective laser melting (SLM) based on added-material manufacturing method is one of the Additive Manufacturing (AM) technologies that can build full density metallic components. In this study, a thermal imager with about 670 nm wavelength was employed to collect build surface process temperature information during SLM fabrication using Monel K500 powder. The major findings are as follows. (1) At nominal process conditions of 600 mm/s beam speed and 180 W beam power, the melt pool has a length of about 0.6 mm and a width of about 0.36 mm. (2) The obtained melt pool length/width ratio is about 1.5 for different build height. With the increase of build height, no clear trend was observed for melt pool length/width ratio and melt pool length value. (3) It is difficult to obtain true temperature in this study but it is possible to estimate melt pool dimension with the identified radiant liquidus temperature.

A Comparative Study Between Selective Laser Melting and Electron Beam Additive Manufacturing Based on Thermal Modeling

2018 ◽  
Author(s):  
M. Shafiqur Rahman ◽  
Paul J. Schilling ◽  
Paul D. Herrington ◽  
Uttam K. Chakravarty
Keyword(s):  
Electron Beam ◽  
Additive Manufacturing ◽  
Heat Source ◽  
Selective Laser Melting ◽  
Thermal Modeling ◽  
Maximum Temperature ◽  
Full Density ◽  
Rate Variation ◽  
Laser Melting ◽  
Melt Pool

Selective Laser Melting (SLM) and Electron Beam Additive Manufacturing (EBAM) are two of the most promising additive manufacturing technologies that can make full density metallic components using layer-by-layer fabrication methods. In this study, three-dimensional computational fluid dynamics models with Ti-6Al-4V powder were developed to conduct numerical simulations of both the SLM and EBAM processes. A moving conical volumetric heat source with Gaussian distribution and temperature-dependent thermal properties were incorporated in the thermal modeling of both processes. The melt-pool geometry and its thermal behavior were investigated numerically and results for temperature profile, cooling rate, variation in specific heat, density, thermal conductivity, and enthalpy were obtained with similar heat source specifications. Results obtained from the two models at the same maximum temperature of the melt pool were then compared to describe their deterministic features to be considered for industrial applications. Validation of the modeling was performed by comparing the EBAM simulation results with the EBAM experimental results for melt pool geometry.

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.

Model of Radiation and Heat Transfer in Laser-Powder Interaction Zone at Selective Laser Melting

2009 ◽  
Vol 131 (7) ◽  
Author(s):  
A. V. Gusarov ◽  
I. Yadroitsev ◽  
Ph. Bertrand ◽  
I. Smurov
Keyword(s):  
Laser Beam ◽  
Selective Laser Melting ◽  
Metallic Powder ◽  
Single Line ◽  
Powder Layer ◽  
Width Ratio ◽  
Beam Diameter ◽  
Laser Melting ◽  
Scanning Velocity ◽  
Melt Pool

A model for coupled radiation transfer and thermal diffusion is proposed, which provides a local temperature field. Single-line scanning of a laser beam over a thin layer of metallic powder placed on a dense substrate of the same material is studied. Both the laser beam diameter and the layer thickness are about 50 μm. The typical scanning velocity is in the range of 10–20 cm/s. An effective volumetric heat source is estimated from laser radiation scattering and absorption in a powder layer. A strong difference in thermal conductivity between the powder bed and dense material is taken into account. The above conditions correspond to the technology of selective laser melting that is applied to build objects of complicated shape from metallic powder. Complete remelting of the powder in the scanned zone and its good adhesion to the substrate ensure fabrication of functional parts with mechanical properties close to the ones of the wrought material. Experiments with single-line melting indicate that an interval of scanning velocities exists, where the remelted tracks are uniform. The tracks become “broken” if the scanning velocity is outside this interval. This is extremely undesirable and referred to as the “balling” effect. The size and the shape of the melt pool and the surface of the metallurgical contact of the remelted material to the substrate are analyzed in relation to the scanning velocity. The modeling results are compared with experimental observation of laser tracks. The experimentally found balling effect at scanning velocities above ∼20 cm/s can be explained by the Plateau–Rayleigh capillary instability of the melt pool. Two factors destabilize the process with increasing the scanning velocity: increasing the length-to-width ratio of the melt pool and decreasing the width of its contact with the substrate.

In-situ capture of melt pool signature in selective laser melting using U-Net-based convolutional neural network

2021 ◽  
Vol 68 ◽  
pp. 347-355
Author(s):  
Qihang Fang ◽  
Zhenbiao Tan ◽  
Hui Li ◽  
Shengnan Shen ◽  
Sheng Liu ◽  
...  
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Selective Laser Melting ◽  
Laser Melting ◽  
Melt Pool

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 Prediction of lack of fusion porosity in selective laser melting based on melt pool monitoring data

2019 ◽  
Vol 25 ◽  
pp. 347-356 ◽  
Author(s):  
Sam Coeck ◽  
Manisha Bisht ◽  
Jan Plas ◽  
Frederik Verbist
Keyword(s):  
Selective Laser Melting ◽  
Monitoring Data ◽  
Laser Melting ◽  
Lack Of Fusion ◽  
Melt Pool

scholarly journals Influence of the Manufacturing Parameters in Selective Laser Melting on Properties of Aluminum Alloy AlSi7Mg0.6 (A357)

2021 ◽  
Vol 45 (1) ◽  
pp. 1-10
Author(s):  
Arnold Mauduit ◽  
Hervé Gransac ◽  
Sébastien Pillot
Keyword(s):  
Aluminum Alloy ◽  
Theoretical Model ◽  
Selective Laser Melting ◽  
Chemical Elements ◽  
Laser Melting ◽  
Operating Modes ◽  
Melt Pool ◽  
Section Area ◽  
Maximum Temperatures ◽  
Conduction Mode

Various selective laser melting (SLM) configurations (8 in all) were tested on aluminum alloy AlSi7Mg0.6 by making single tracks on parallelepipeds specimens. We used an energy balance as a means of connecting the machine parameters (power, speed, etc.) of the 8 configurations to the morphology (geometry) of the single tracks. On this basis, we correlated the width, depth and especially the section area of the melt pool (single track) to the linear energy density. We were also able to assess the absorption coefficient of the aluminum alloy AlSi7Mg0.6 as a function of the temperature. The study was then focused on the microstructure and the possible impacts on the material properties including on the mechanical characteristics and the anisotropy observed in literature based on the build direction. Evidence suggests that the Hall-Petch relation can be used to explain this anisotropy. The thermal analysis highlighted two laser operating modes: the keyhole mode and the conduction mode. These modes have also been described via the morphology of the single tracks. Finally, a comparison between Rosenthal’s theoretical model (in the case of the conduction mode) and actual conditions was proposed by the obtained geometry of the single tracks as well as the cooling speeds calculated and measured using the dendrite arm spacing (DAS). The maximum temperatures achieved were also assessed by Rosenthal’s theoretical model which made it possible to explain the evaporation of some chemical elements during the manufacturing of the aluminum alloy through SLM.

scholarly journals Texture control of 316L parts by modulation of the melt pool morphology in selective laser melting

2019 ◽  
Vol 264 ◽  
pp. 21-31 ◽  
Author(s):  
Olivier Andreau ◽  
Imade Koutiri ◽  
Patrice Peyre ◽  
Jean-Daniel Penot ◽  
Nicolas Saintier ◽  
...  
Keyword(s):  
Selective Laser Melting ◽  
Laser Melting ◽  
Melt Pool
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