Melting and Resolidification of a Two-Component Metal Powder Layer Heated by a Moving Gaussian Heat Source

2003 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Steady State ◽  
Heat Source ◽  
Coordinate System ◽  
Metal Powder ◽  
Powder Layer ◽  
Moving Heat Source ◽  
Metal Powders ◽  
Melting Points ◽  
Scanning Velocity ◽  
Two Component

Melting and resolidification of a subcooled mixed metal powder layer that contains a mixture of two metal powders with significantly different melting points heated by a moving Gaussian heat source is investigated numerically. The phase change is modeled using a temperature-transforming model and shrinkage induced by melting is also taken into account. The problem appears to be steady-state since it is formulated in a coordinate system moving with the Gaussian heat source and the size of the powder is much larger than that of the heat source. The results show that the powder layer thickness, moving heat source intensity and scanning velocity have significant effects on the sintering depth.

Three-Dimensional Modeling of Laser Sintering of a Two-Component Metal Powder Layer on Top of Sintered Layers

2006 ◽  
Vol 129 (3) ◽  
pp. 575-582 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Metal Powder ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Three Dimensional Model ◽  
Scanning Velocity ◽  
Laser Beam Intensity ◽  
Two Component

A three-dimensional model of selective laser sintering of a two-component loose metal powder layer on top of previously sintered layers by a single-line laser scanning is presented. A temperature-transforming model is employed to model melting and resolidification accompanied by partial shrinkage during laser sintering. The heat losses at the top surface due to natural convection and radiation are taken into account. The liquid flow of the molten low-melting-point metal powders, which is driven by capillary and gravity forces, is also considered and formulated by using Darcy’s law. The effects of the dominant processing parameters, such as laser-beam intensity, scanning velocity, and number of the existing sintered layers underneath, are investigated.

Three-Dimensional Modeling of Selective Laser Sintering of Two-Component Metal Powder Layers

2005 ◽  
Vol 128 (1) ◽  
pp. 299-306 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Metal Powder ◽  
Continuous Wave ◽  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Three Dimensional Modeling

Laser sintering of a metal powder mixture that contains two kinds of metal powders with significantly different melting points under a moving Gaussian laser beam is investigated numerically. The continuous-wave laser-induced melting accompanied by shrinkage and resolidification of the metal powder layer are modeled using a temperature-transforming model. The liquid flow of the melted low-melting-point metal driven by capillary and gravity forces is also included in the physical model. The numerical results are validated by experimental results, and a detailed parametric study is performed. The effects of the moving heat source intensity, the scanning velocity, and the thickness of the powder layer on the sintering depth, the configuration of the heat affected zone, and the temperature distribution are discussed.

Melting and Resolidification of a Subcooled Mixed Powder Bed With Moving Gaussian Heat Source

1998 ◽  
Vol 120 (4) ◽  
pp. 883-891 ◽  
Author(s):  
Yuwen Zhang ◽  
A. Faghri
Keyword(s):  
Heat Source ◽  
Melting Process ◽  
Liquid Pool ◽  
Surface Heat ◽  
Moving Heat Source ◽  
Melting Points ◽  
Mixed Powder ◽  
Scanning Velocity ◽  
Powder Bed ◽  
Effect Of Surface

Melting of a subcooled powder bed that contains a mixture of two powders with significantly different melting points under a moving Gaussian heat source was investigated numerically. Shrinkage induced by the density change on the melting process was taken into account in the physical model. The problem is formulated using a temperature transforming model and solved by the finite difference method. The results show that the effect of surface heat loss due to convection and radiation is not negligible regardless of whether the shrinkage phenomena is considered. The decrease of moving heat source intensity will result in decrease of the sintering depth and the volume of the liquid pool. The increase of the scanning velocity will decrease the sintering depth and the location and shape of the liquid pool is affected significantly.

Three-Dimensional Simulation of Multiple-Line Laser Sintering of a Two-Component Metal Powder Layer on Top of Sintered Layers

2005 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Laser Beam ◽  
Metal Powder ◽  
Scanning Speed ◽  
Processing Parameters ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Laser Beam Intensity ◽  
Multiple Line ◽  
Two Component

Multiple line laser scan sintering of a two-component metal powder layer on top of the sintered layers with a moving circular Gaussian laser beam is modeled numerically. The overlap between the adjacent scan lines to achieve enhanced bonding is taken into account. The binding between the newly sintered layer and existing sintered layers underneath through melting is also considered. The governing equation is formulated by a temperature-transforming model with partial shrinkage induced by melting considered. The liquid flow of the molten low melting point metal powders, which is driven by capillary and gravity forces, is formulated by Darcy’s law. The effects of the dominant processing parameters, including the moving laser beam intensity, scanning speed and number of the existing sintered layers underneath, on the shape of the heat affected zone (HAZ) are investigated. A parametric study is performed and the best combination of the processing parameters is recommended.

Analysis and modeling of direct selective laser sintering of two-component metal powders

2005 ◽  
Author(s):  
◽  
Tiebing Chen
Keyword(s):  
Laser Beam ◽  
Selective Laser Sintering ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Gaussian Laser Beam ◽  
Scanning Velocity ◽  
Two Component

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] Direct Selective Laser Sintering (SLS) is an emerging technology of Solid Freeform Fabrication (SFF) that 3-D parts are built from the metal-based powder bed with CAD data. A one-dimensional analytical model of melting in a two-component powder layer with finite thickness subjected to a constant heat flux heating and a two-dimensional numerical model of SLS of a two-component powder layer with a moving laser beam scanning were developed consecutively. Three-dimensional modeling of laser sintering of a two-component metal powder mixture under a moving Gaussian laser beam was investigated numerically at last. The effects of the moving heat source intensity, the scanning velocity, the thickness of the powder layer and the number of existing sintered layers underneath on the sintering depth, the configuration of the heat affected zone (HAZ) and the temperature distribution are discussed.

scholarly journals Heat Source Modeling in Selective Laser Melting

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2052 ◽  
Author(s):  
Elham Mirkoohi ◽  
Daniel E. Seivers ◽  
Hamid Garmestani ◽  
Steven Y. Liang
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Heat Source ◽  
Material Properties ◽  
Physical Phenomenon ◽  
Three Dimensional ◽  
Moving Heat Source ◽  
Point Heat Source ◽  
Laser Melting ◽  
Source Models

Selective laser melting (SLM) is an emerging additive manufacturing (AM) technology for metals. Intricate three-dimensional parts can be generated from the powder bed by selectively melting the desired location of the powders. The process is repeated for each layer until the part is built. The necessary heat is provided by a laser. Temperature magnitude and history during SLM directly determine the molten pool dimensions, thermal stress, residual stress, balling effect, and dimensional accuracy. Laser-matter interaction is a crucial physical phenomenon in the SLM process. In this paper, five different heat source models are introduced to predict the three-dimensional temperature field analytically. These models are known as steady state moving point heat source, transient moving point heat source, semi-elliptical moving heat source, double elliptical moving heat source, and uniform moving heat source. The analytical temperature model for all of the heat source models is solved using three-dimensional differential equations of heat conduction with different approaches. The steady state and transient moving heat source are solved using a separation of variables approach. However, the rest of the models are solved by employing Green’s functions. Due to the high temperature in the presence of the laser, the temperature gradient is usually high which has a substantial impact on thermal material properties. Consequently, the temperature field is predicted by considering the temperature sensitivity thermal material properties. Moreover, due to the repeated heating and cooling, the part usually undergoes several melting and solidification cycles, and this physical phenomenon is considered by modifying the heat capacity using latent heat of melting. Furthermore, the multi-layer aspect of the metal AM process is considered by incorporating the temperature history from the previous layer since the interaction of the layers have an impact on heat transfer mechanisms. The proposed temperature field models based on different heat source approaches are validated using experimental measurement of melt pool geometry from independent experimentations. A detailed explanation of the comparison of models is also provided. Moreover, the effect of process parameters on the balling effect is also discussed.

Partial Melting and Resolidification of Single-Component Metal Powder With a Moving Laser Beam

2005 ◽  
Author(s):  
Bin Xiao ◽  
Yuwen Zhang
Keyword(s):  
Melting Point ◽  
Laser Beam ◽  
Partial Melting ◽  
Metal Powder ◽  
Liquid Pool ◽  
Single Component ◽  
Solid Core ◽  
Metal Powders ◽  
Scanning Velocity ◽  
Laser Beam Intensity

Partial melting and resolidification of single-component metal powders with a moving laser beam is investigated numerically. Since laser processing of metal powder is a very rapid process, the liquid layer and solid core of a partially molten powder particle may not at thermal equilibrium and have different temperatures: the temperature of the liquid part is higher than the melting point, and the temperature of the solid core is below the melting point. Therefore, the local temperature of regions with partial molten particles is within a range of temperature adjacent to the melting point, instead of at the melting point. The partial melting of the metal powder is also accompanied by shrinkage that drives out the gas in the powder bed and the powder structure is supported by the solid core of the partially melted powder particles. Melting with shrinkage and resolidification are described using a temperature transforming model. The convection driven by capillary and gravity forces in the melting liquid pool is formulated by using Darcy’s law. The effects of laser beam intensity and scanning velocity on the shape and size of the heat affected zone and molten pool are investigated.

scholarly journals Heat Source Modeling in Selective Laser Melting

2019 ◽  
Author(s):  
Elham Mirkoohi ◽  
Daniel E. Seivers ◽  
Hamid Garmestani ◽  
Steven Y. Liang
Keyword(s):  
Temperature Field ◽  
Steady State ◽  
Heat Source ◽  
Material Properties ◽  
Physical Phenomenon ◽  
Three Dimensional ◽  
Moving Heat Source ◽  
Point Heat Source ◽  
Laser Melting ◽  
Source Models

Selective laser melting is an emerging Additive Manufacturing (AM) technology for metals. Intricate three-dimensional parts can be generated from the powder bed by selectively melting the desired location of the powders. The process is repeated for each layer until the part is built. The necessary heat is provided by a laser. Temperature magnitude and history during SLM directly determine the molten pool dimensions, thermal stress, residual stress, balling effect, and dimensional accuracy. Laser-matter interaction is a crucial physical phenomenon in the SLM process. In this paper, five different heat source models are introduced to predict the three-dimensional temperature field analytically. These models are known as steady state moving point heat source, transient moving point heat source, semi-elliptical moving heat source, double elliptical moving heat source, and uniform moving heat source. The analytical temperature model for all of the heat source models are solved using three-dimensional differential equation of heat conduction with different approaches. The Steady state and transient moving heat source are solved using separation of variables approach. However, the rest of models are solved by employing the Green’s functions. Due to the high magnitude of the temperature in the presence of the laser, the temperature gradient is usually high which has a substantial impact on thermal material properties. Consequently, the temperature field is predicted by considering the temperature sensitivity thermal material properties. Moreover, due to the repeated heating and cooling, the part usually undergoes several melting and solidification cycles, this physical phenomenon is considered by modifying the heat capacity using latent heat of melting. Furthermore, the multi-layer aspect of metal AM process is considered by incorporating the temperature history from the previous layer since the interaction of the layers have an impact on heat transfer mechanisms. The proposed temperature field models based on different heat source approaches are validated using experimental measurement of melt pool geometry from independent experimentations. The detailed explanation of the comparison of models is also provided. Moreover, the effect of process parameters on the balling effect is also discussed.

Sign in / Sign up

Export Citation Format

Share Document