Electron beam melting® (EBM) is one of the fastest growing additive manufacturing processes capable of building parts with complex geometries, made predominantly of Ti-alloys. Providing an understanding of the effects of process parameters on the heat distribution in a specimen built by EBM®, could be the preliminary step toward the microstructural and consequently mechanical properties control. Numerical modeling is a useful tool for the optimization of processing parameters, because it decreases the level of required experimentation and significantly saves on time and cost. So far, a few numerical models are developed to investigate the effects of EBM® process parameters on the heat distribution and molten pool geometry. All of the numerical models have ignored the material convection inside the molten pool that affects the real presentation of the temperature distribution and the geometry of molten pool. In this study, a moving electron beam heat source and temperature dependent properties of Ti-6Al-4V were used in order to provide a 3D thermal-fluid flow model of EBM®. The influence of process parameters including electron beam scanning speed, electron beam current, and the powder bed density were studied. Also, the effects of flow convection in temperature distribution and molten pool geometry were investigated by comparing a pure-thermal with the developed thermal-fluid flow model. According to the results, the negative temperature coefficient of surface tension in Ti-6Al-4V was responsible for the formation of an outward flow in the molten pool. Also, results showed that ignoring the material convection inside the molten pool resulted in the formation of a molten pool with narrower width and shorter length, while it had a deeper penetration and higher maximum temperature in the molten pool. Increasing the powder bed density was accompanied with an increase in the thermal conductivity of the powder bed that resulted in a reduction in the molten pool width on the powder bed top surface. Experimental measurements of molten pool width and depth are performed to validate the numerical model.

References

References
1.
Al-Bermani
,
S.
,
Blackmore
,
M.
,
Zhang
,
W.
, and
Todd
,
I.
,
2010
, “
The Origin of Microstructural Diversity, Texture, and Mechanical Properties in Electron Beam Melted Ti-6Al-4V
,”
Metall. Mater. Trans. A
,
41
(
13
), pp.
3422
3434
.10.1007/s11661-010-0397-x
2.
Brandl
,
E.
, and
Greitemeier
,
D.
,
2012
, “
Microstructure of Additive Layer Manufactured Ti-6Al-4V After Exceptional Post Heat Treatments
,”
Mater. Lett.
,
81
, pp.
84
87
.10.1016/j.matlet.2012.04.116
3.
Gil Mur
,
F. X.
,
Rodriguez
,
D.
, and
Planell
,
J. A.
,
1996
, “
Influence of Tempering Temperature and Time on the α′-Ti-6Al-4V Martensite
,”
J. Alloys Compd.
,
234
(
2
), pp.
287
289
.10.1016/0925-8388(95)02057-8
4.
Yamaguchi
,
M.
,
Johnson
,
D. R.
,
Lee
,
H. N.
, and
Inui
,
H.
,
2000
, “
Directional Solidification of TiAl-Base Alloys
,”
Intermetallics
,
8
(
5
), pp.
511
517
.10.1016/S0966-9795(99)00157-0
5.
Mok
,
S. H.
,
Bi
,
G.
,
Folkes
,
J.
,
Pashby
,
I.
, and
Segal
,
J.
,
2008
, “
Deposition of Ti–6Al–4V Using a High Power Diode Laser and Wire, Part II: Investigation on the Mechanical Properties
,”
Surf. Coat. Technol.
,
202
(
19
), pp.
4613
4619
.10.1016/j.surfcoat.2008.03.028
6.
Kobryn
,
P. A.
, and
Semiatin
,
S. L.
,
2003
, “
Microstructure and Texture Evolution During Solidification Processing of Ti–6Al–4V
,”
J. Mater. Process. Technol.
,
135
(
2
), pp.
330
339
.10.1016/S0924-0136(02)00865-8
7.
Gaytan
,
S. M.
,
Murr
,
L. E.
,
Medina
,
F.
,
Martinez
,
E.
,
Lopez
,
M. I.
, and
Wicker
,
R. B.
,
2009
, “
Advanced Metal Powder Based Manufacturing of Complex Components by Electron Beam Melting
,”
Mater. Technol.
,
24
(
3
), pp.
181
190
.10.1179/106678509X12475882446133
8.
Murr
,
L. E.
,
Quinones
,
S. A.
,
Gaytan
,
S. M.
,
Lopez
,
M. I.
,
Rodela
,
A.
,
Martinez
,
E. Y.
,
Hernandez
,
D. H.
,
Martinez
,
E.
,
Medina
,
F.
, and
Wicker.
,
R. B.
,
2009
, “
Microstructure and Mechanical Behavior of Ti–6Al–4V Produced by Rapid-Layer Manufacturing, for Biomedical Applications
,”
J. Mech. Behav. Biomed.
,
2
(
1
), pp.
20
32
.10.1016/j.jmbbm.2008.05.004
9.
Bontha
,
S.
,
Klingbeil
,
N. W.
,
Kobryn
,
P. A.
, and
Fraser
,
H. L.
,
2009
, “
Effects of Process Variables and Size-Scale on Solidification Microstructure in Beam-Based Fabrication of Bulky 3D Structures
,”
Mater. Sci. Eng., A
,
513
(
15
), pp.
311
318
.10.1016/j.msea.2009.02.019
10.
Antonysamy
,
A. A.
,
Prangnell
,
P. B.
, and
Meyer
,
J.
,
2012
, “
Effect of Wall Thickness Transitions on Texture and Grain Structure in Additive Layer Manufacture (ALM) of Ti-6Al-4V
,”
Mater. Sci. Forum
,
706
, pp.
205
210
.10.4028/www.scientific.net/MSF.706-709.205
11.
Murr
,
L. E.
,
Esquivel
,
E. V.
,
Quinones
,
S. A.
,
Gaytan
,
S. M.
,
Lopez
,
M. I.
,
Martinez
,
E. Y.
,
Medina
,
F.
,
Hernandez
,
D. H.
,
Martinez
,
E.
,
Martinez
,
J. L.
,
Brown
,
D. K.
,
Hoppe
,
T.
,
Meyers
,
W.
,
Lindhe
,
U.
, and
Wicker
,
R. B.
,
2009
, “
Microstructures and Mechanical Properties of Electron Beam-Rapid Manufactured Ti–6Al–4V Biomedical Prototypes Compared to Wrought Ti–6Al–4V
,”
Mater. Charact.
,
60
(
2
), pp.
96
105
.10.1016/j.matchar.2008.07.006
12.
Körner
,
C.
,
Attar
,
E.
, and
Heinl
,
P.
,
2011
, “
Mesoscopic Simulation of Selective Beam Melting Processes
,”
J. Mater. Process. Technol.
,
211
(
6
), pp.
978
987
.10.1016/j.jmatprotec.2010.12.016
13.
Mahale
,
T. R.
,
2009
, “
Electron Beam Melting of Advanced Materials and Structures
,” Ph.D. thesis,
North Carolina State University
,
Raleigh, NC
.
14.
Zäh
,
M. F.
, and
Lutzmann
,
S.
,
2010
, “
Modelling and Simulation of Electron Beam Melting
,”
Prod. Eng. Res. Dev.
,
4
(
1
), pp.
15
23
.10.1007/s11740-009-0197-6
15.
Shen
,
N.
, and
Chou
,
Y. K.
,
2012
, “
Thermal Modeling of Electron Beam Additive Manufacturing Process—Powder Sintering Effects
,”
Proceedings of the 7th ASME 2012 International Manufacturing Science and Engineering Conference
,
Notre Dame, IN
.
16.
Shen
,
N.
, and
Chou
,
Y. K.
,
2012
, “
Numerical Thermal Analysis in Electron Beam Additive Manufacturing With Preheating Effects
,”
Proceedings of the 23rd Solid Freeform Fabrication Symposium
,
Austin, TX
, pp.
774
784
.
17.
Scharowsky
,
T.
,
Bauereiß
,
A.
,
Singer
,
R. F.
, and
Körner
,
C.
,
2012
, “
Observation and Numerical Simulation of Molten Pool Dynamic and Beam Powder Interaction During Selective Electron Beam Melting
,”
Proceedings of the 23rd Solid Freeform Fabrication Symposium
,
Austin, TX
, pp.
815
820
.
18.
Rai
,
T. A.
,
Elmer
,
R.
,
Palmer
,
J. W.
, and
Debroy
,
T.
,
2007
, “
Heat Transfer and Fluid Flow During Keyhole Mode Laser Welding of Tantalum, Ti–6Al–4V, 304L Stainless Steel and Vanadium
,”
J. Phys. D
,
40
(
18
), pp.
5753
5766
.10.1088/0022-3727/40/18/037
19.
Li
,
J. F.
,
Li
,
L.
, and
Stott
,
F. H.
,
2004
, “
A Three-Dimensional Numerical Model for a Convection-Diffusion Phase Change Process During Laser Melting of Ceramic Materials
,”
Int. J. Heat Mass Transfer
,
47
(
25
), pp.
5523
5539
.10.1016/j.ijheatmasstransfer.2004.07.024
20.
Chahine
,
G.
,
2011
, “
Application of Digital Engineering in the Development of a Bio-Adaptable Dental Implant
,” Ph.D. thesis,
Southern Methodist University
,
Dallas, TX
.
22.
Jamshidinia
,
M.
,
Kong
,
F.
, and
Kovacevic
,
R.
,
2012
, “
Temperature Distribution and Fluid Flow Modeling of Electron Beam Melting® (EBM)
,”
Proceedings of the ASME International Mechanical Engineering Congress and Exposition, Part D, Fluid and Heat Transfer
, Vol.
7
,
Houston, TX
, IMECE2012-89440, pp.
3089
3102
.
23.
Wen
,
S.
, and
Shin
,
Y. C.
,
2010
, “
Modeling of Transport Phenomena During the Coaxial Laser Direct Deposition Process
,”
J. Appl. Phys.
,
108
(
4
), p.
044908
.10.1063/1.3474655
24.
Zhang
,
W.
,
Kim
,
C. H.
, and
DebRoy
,
T.
,
2004
, “
Heat and Fluid Flow in Complex Joints During Gas Metal Arc Welding—Part I: Numerical Model of Fillet Welding
,”
J. Appl. Phys.
,
95
(
9
), pp.
5210
5219
.10.1063/1.1699485
25.
Qin
,
Y.
,
Zou
,
J.
,
Dong
,
C.
,
Wang
,
X.
,
Wu
,
A.
,
Liu
,
Y.
,
Hao
,
S.
, and
Guan
,
Q.
,
2004
, “
Temperature–Stress Fields and Related Phenomena Induced by a High Current Pulsed Electron Beam
,”
Nucl. Instrum. Methods Phys. Res. B
,
225
(
4
), pp.
544
554
.10.1016/j.nimb.2004.06.008
26.
Mishra
,
S.
, and
DebRoy
,
T.
,
2005
, “
A Computational Procedure for Finding Multiple Solutions of Convective Heat Transfer Equations
,”
J. Phys. D: Appl. Phys.
,
38
(
16
), pp.
2977
2985
.10.1088/0022-3727/38/16/034
27.
Li
,
J. F.
,
Li
,
L.
, and
Stott
,
F. H.
,
2004
, “
Predictions of Flow Velocity and Velocity Boundary Layer Thickness at the Surface During Laser Melting of Ceramic Materials
,”
J. Phys. D: Appl. Phys.
,
37
(
12
), pp.
1710
1717
.10.1088/0022-3727/37/12/018
28.
Rai
,
R.
,
Burgardt
,
P.
,
Milewski
,
J. O.
,
Lienert
,
T. J.
, and
DebRoy
,
T.
,
2009
, “
Heat Transfer and Fluid Flow During Electron Beam Welding of 21Cr–6Ni–9Mn Steel and Ti–6Al–4V Alloy
,”
J. Phys. D: Appl. Phys.
,
42
(
2
), p.
025503
.10.1088/0022-3727/42/2/025503
29.
Rai
,
R.
,
Roy
,
G. G.
, and
DebRoy
,
T.
,
2007
, “
A Computationally Efficient Model of Convective Heat Transfer and Solidification Characteristics During Keyhole Mode Laser Welding
,”
J. Appl. Phys.
,
101
(
5
), p.
054909
.10.1063/1.2537587
30.
Ioannou
,
Y.
, and
Doumanidis
,
C.
,
2010
, “
Analytical Model for Geometrical Characteristics Control of Laser Sintered Surfaces
,”
Int. J. Nanomanuf.
,
6
(
1
), pp.
300
311
.10.1504/IJNM.2010.034792
31.
Mills
,
K. C.
,
2002
,
Recommended Values of Thermophysical Properties for Selected Commercial Alloys
,
Woodhead Publishing Limited
,
Cambridge, UK
, p.
217
.
32.
Verhaeghe
,
F.
,
Craeghs
,
T.
,
Heulens
,
J.
, and
Pandelaers
,
L.
,
2009
, “
A Pragmatic Model for Selective Laser Melting With Evaporation
,”
Acta Mater.
,
57
(
20
), pp.
6006
6012
.10.1016/j.actamat.2009.08.027
33.
Dai
,
K.
,
Li
,
X.
, and
Shaw
,
L.
,
2004
, “
Thermal Analysis of Laser-Densified Dental Porcelain Bodies: Modeling and Experiments
,”
ASME J. Heat Transfer
,
126
(
5
), pp.
818
825
.10.1115/1.1795812
34.
Gusarov
,
A. V.
,
Laoui
,
T.
,
Froyen
,
L.
, and
Titov
,
V. I.
,
2003
, “
Contact Thermal Conductivity of a Powder Bed in Selective Laser Sintering
,”
Int. J. Heat Mass Transfer
,
46
(
6
), pp.
1103
1109
.10.1016/S0017-9310(02)00370-8
35.
Tolochko
,
N. K.
,
Arshinov
,
M. K.
,
Gusarov
,
A. V.
,
Titov
,
V. I.
,
Laoui
,
T.
, and
Froyen
,
L.
,
2003
, “
Mechanisms of Selective Laser Sintering and Heat Transfer in Ti Powder
,”
Rapid Prototyping J.
,
9
(
5
), pp.
314
326
.10.1108/13552540310502211
36.
Zhou
,
J.
,
Zhang
,
Y.
, and
Chen
,
J. K.
,
2009
, “
Numerical Simulation of Random Packing of Spherical Particles for Powder-Based Additive Manufacturing
,”
ASME J. Manuf. Sci. Eng.
,
131
(
3
), p.
031004
.10.1115/1.3123324
37.
Liou
,
F.
,
Fan
,
Z.
,
Pan
,
H.
,
Slattery
,
K.
,
Kinsella
,
M.
,
Newkirk
,
J.
, and
Chou
,
H.-N.
,
2007
, “
Modeling and Simulation of a Laser Deposition Process
,”
Proceedings of the 18th Solid Freeform Fabrication Symposium
,
Austin, TX
, pp.
212
223
.
You do not currently have access to this content.