Three-Dimensional Sintering of Two-Component Metal Powders With Stationary and Moving Laser Beams

1999 ◽  
Vol 122 (1) ◽  
pp. 150-158 ◽  
Author(s):  
Yuwen Zhang ◽  
A. Faghri ◽  
C. W. Buckley ◽  
T. L. Bergman
Keyword(s):  
Energy Equation ◽  
Three Dimensional ◽  
Steel Powder ◽  
Metal Powders ◽  
Sintering Process ◽  
Gaussian Laser Beam ◽  
Cross Sectional ◽  
Scanning Velocity ◽  
Powder Bed ◽  
Gravity Forces

Melting and resolidification of a mixture of two metal powders with significantly different melting points under irradiation of a stationary or a moving Gaussian laser beam were investigated numerically and experimentally. The liquid motion driven by capillary and gravity forces as well as the shrinkage of the powder bed caused by the overall density change were taken into account in the physical model. The liquid flow was formulated by using Darcy’s law, and the energy equation was given using a temperature transforming model. Prediction were compared with experimental results obtained with nickel braze and AISI 1018 steel powder. The effects of laser properties and the scanning velocity on the laser sintering process were also investigated. An empirical correlation that can be used to predict the cross-sectional area of the heat affected zone is proposed. [S0022-1481(00)70201-5]

3-D Sintering of Two-Component Metal Powders With Stationary and Moving Laser Beams

1999 ◽  
Author(s):  
Yuwen Zhang ◽  
A. Faghri ◽  
C. W. Buckley ◽  
T. L. Bergman
Keyword(s):  
Energy Equation ◽  
Steel Powder ◽  
Metal Powders ◽  
Sintering Process ◽  
Gaussian Laser Beam ◽  
Cross Sectional ◽  
Scanning Velocity ◽  
Powder Bed ◽  
Gravity Forces ◽  
Model Predictions

Abstract Melting and resolidification of a mixture of two metal powders with significantly different melting points under irradiation of a stationary or a moving Gaussian laser beam were investigated numerically and experimentally. The liquid motion driven by capillary and gravity forces as well as the shrinkage of the powder bed caused by the overall density change were taken into account in the physical model. The liquid flow was formulated by using Darcy’s law, and the energy equation was given using a temperature transforming model. Predictions were compared with experimental results obtained with nickel braze and AISI 1018 steel powder. The effects of laser properties and the scanning velocity on the laser sintering process were also investigated. An empirical correlation that can be used to predict the of cross sectional area of the heat affected zone is proposed.

Numerical Simulation of Direct Metal Laser Sintering of Single-Component Powder on Top of Sintered Layers

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
Bin Xiao ◽  
Yuwen Zhang
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Laser Sintering ◽  
Liquid Pool ◽  
Sintering Process ◽  
Direct Metal Laser Sintering ◽  
Three Dimensional Model ◽  
Gaussian Laser Beam ◽  
Scanning Velocity

A three-dimensional model describing melting and resolidification of direct metal laser sintering of loose powders on top of sintered layers with a moving Gaussian laser beam is developed. Natural convection in the liquid pool driven by buoyancy and Marangoni effects is taken into account. A temperature transforming model is employed to model melting and resolidification in the laser sintering process. The continuity, momentum, and energy equations are solved using a finite volume method. The effects of dominant processing parameters including number of the existing sintered layers underneath, laser scanning velocity, and initial porosity on the sintering process 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.

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.

Numerical Simulation of Direct Metal Laser Sintering of Single-Component Powder on Top of Sintered Layers

2006 ◽  
Author(s):  
Bin Xiao ◽  
Yuwen Zhang
Keyword(s):  
Laser Scanning ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Laser Sintering ◽  
Liquid Pool ◽  
Sintering Process ◽  
Direct Metal Laser Sintering ◽  
Three Dimensional Model ◽  
Gaussian Laser Beam ◽  
Scanning Velocity

A three dimensional model describing melting and resolidification of direct metal laser sintering of loose powders on top of sintered layers with a moving Gaussian laser beam is developed. Natural convection in the liquid pool driven by buoyancy and Marangoni effects is taken into account. A temperature transforming model is employed to model melting and resolidification in the laser sintering process. The continuity, momentum, and energy equations are solved using a finite volume method. Effects of dominant processing parameters including number of the existing sintered layers underneath, laser scanning velocity and initial porosity on the sintering process are investigated.

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

2005 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Three Dimensional ◽  
Processing Parameters ◽  
Laser Sintering ◽  
Powder Layer ◽  
Metal Powders ◽  
Scanning Velocity ◽  
Three Dimensional Modeling ◽  
Sintered Metal ◽  
Gravity Forces

A three-dimensional numerical model of Selective Laser Sintering (SLS) of the metal powders for a single scan line induced by a moving laser beam interacted with a loose powder layer on top of the sintered metal layers is presented. The problem is modeled using a temperature-transforming model and the partial shrinkage induced by melting is accounted for. The heat losses at the top surface due to the 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 the moving heat source intensity, scanning velocity and number of the existing sintered layers underneath are investigated. A parametric study is performed and the best combination of the processing parameters is recommended.

Analysis of Melting in a Mixed Metal Powder Bed With Finite Thickness Subjected to Constant Heat Flux Heating

2003 ◽  
Author(s):  
Tiebing Chen ◽  
Yuwen Zhang
Keyword(s):  
Selective Laser Sintering ◽  
Finite Thickness ◽  
Three Dimensional ◽  
Constant Heat Flux ◽  
Metal Powders ◽  
Powder Bed ◽  
Solid Foundation ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Liquid And Solid Phases

Melting of a subcooled powder bed with the finite thickness that contains a mixture of two metal powders with significantly different melting points is investigated analytically. Shrinkage induced by melting is taken into account in the physical model. The temperature distributions in the liquid and solid phases were obtained using an exact solution and an integral approximate solution, respectively. The effects of porosity, Stefan number, and subcooling on the surface temperature and solid-liquid interface are also investigated. The present work built solid foundation to investigate the complex three-dimensional selective laser sintering (SLS) process.

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.

Study on New Ceramic Coated Metal Powders: Microstructure and Properties

2005 ◽  
Vol 290 ◽  
pp. 284-287 ◽  
Author(s):  
Marco Actis Grande ◽  
Roxana M. Piticescu ◽  
C. Bogdanescu ◽  
Mario Rosso ◽  
Daniele Ugues
Keyword(s):  
Steel Powder ◽  
Metal Powders ◽  
Sintering Process ◽  
Bending Tests ◽  
Hard Particles ◽  
Coated Metal ◽  
Uniform Dispersion ◽  
Near Net Shape ◽  
New Generation ◽  
Metal Sintering

Metal/ceramic composite materials were produced with core/shell structure by traditional pressing and the influence of the compacting parameters on the material properties has been studied. Different quantities of ceramic have been introduced to coat the base stainless steel powder. The use of a new generation of coated powders gives the opportunity to achieve near net shape massive composite exhibiting a composite microstructure, with a uniform dispersion of ceramic hard particles embedded in the metal matrix. Sintering was carried out in vacuum and at temperatures typical of metal sintering process (1250 °C). Microstructures of produced samples have been investigated through the use of LOM and SEM. Hardness as well as tensile and bending tests have been performed.

Keyhole threshold and morphology in laser melting revealed by ultrahigh-speed x-ray imaging

Science ◽  
2019 ◽  
Vol 363 (6429) ◽  
pp. 849-852 ◽  
Author(s):  
Ross Cunningham ◽  
Cang Zhao ◽  
Niranjan Parab ◽  
Christopher Kantzos ◽  
Joseph Pauza ◽  
...  
Keyword(s):  
Cross Sections ◽  
Three Dimensional ◽  
High Energy ◽  
X Rays ◽  
Laser Melting ◽  
Scanning Velocity ◽  
Powder Bed ◽  
Three Dimensional Printing ◽  
X Ray ◽  
X Ray Imaging

We used ultrahigh-speed synchrotron x-ray imaging to quantify the phenomenon of vapor depressions (also known as keyholes) during laser melting of metals as practiced in additive manufacturing. Although expected from welding and inferred from postmortem cross sections of fusion zones, the direct visualization of the keyhole morphology and dynamics with high-energy x-rays shows that (i) keyholes are present across the range of power and scanning velocity used in laser powder bed fusion; (ii) there is a well-defined threshold from conduction mode to keyhole based on laser power density; and (iii) the transition follows the sequence of vaporization, depression of the liquid surface, instability, and then deep keyhole formation. These and other aspects provide a physical basis for three-dimensional printing in laser powder bed machines.

Sign in / Sign up

Export Citation Format

Share Document