This study theoretically investigates the effects of the entrainment accompanying mass, momentum, and energy transport on pore size during high power density laser and electron beam welding processes. The physics of macroporosity formation is not well understood, even though macroporosity often occurs and limits the widespread industrial application of keyhole mode welding. This work is an extension of a previous work dealing with collapses of keyholes induced by high intensity beam drilling. In order to determine the pore shape, this study, however, introduces the equations of state at the times when the keyhole is about to be enclosed and when the temperature drops to melting temperature. The gas pressure required at the time when keyhole collapses is determined by calculating the compressible flow of the two-phase, vapor–liquid dispersion in a vertical keyhole with varying cross sections, paying particular attention to the transition between annular and slug flows. It is found that the pore size increases as entrainment fluxes decrease in the lower and upper regions of the keyhole containing a supersonic mixture. The pore size also increases with decreasing total energy of entrainment and an increasing axial velocity component ratio between entrainment and mixture through the core region. With a subsonic mixture in the keyhole, the final pore size increases with entrainment fluxes in the lower and upper regions. This work provides an exploratory and systematical investigation of pore size induced by entrainment accompanied by mass, momentum, and energy transport during keyhole mode welding.

References

References
1.
Arata
,
Y.
,
1986
,
Plasma, Electron and Laser Beam Technology
,
American Society for Metals, Metals Park
,
OH
.
2.
Kou
,
S.
,
1987
,
Welding Metallurgy
,
Wiley
,
New York
.
3.
DebRoy
,
T.
, and
David
,
S. A.
,
1995
, “
Physical Processes in Fusion Welding
,”
Rev. Mod. Phys.
,
67
, pp.
85
112
.10.1103/RevModPhys.67.85
4.
Duley
,
W. W.
,
1999
,
Laser Welding
,
Wiley
,
New York
.
5.
Elmer
,
J. W.
,
Palmer
,
T. A.
,
Babu
,
S. S.
,
Zhang
,
W.
, and
DebRoy
,
T.
,
2004
, “
Phase Transformation Dynamics during Welding of Ti-6Al-AV
,”
J. Appl. Phys.
,
95
(
12
), pp.
8327
8339
.10.1063/1.1737476
6.
Tong
,
H.
, and
Giedt
,
W. H.
,
1970
, ”
A Dynamic Interpretation of Electron Beam Welding
,”
Weld. J.
,
49
, pp.
259
266
.
7.
Pastor
,
M.
,
Zhao
,
H.
, and
DebRoy
,
T.
,
2001
, “
Pore Formation During Continuous Wave Nd:YAG Laser Welding of Aluminum for Automotive Applications
,”
Weld. Int.
,
15
(
4
), pp.
275
281
.10.1080/09507110109549355
8.
Matsunawa
,
A.
,
Seto
,
N.
,
Kim
,
J.-D.
,
Mizutani
,
M.
, and
Katayama
,
S.
,
2001
, “
Observation of Keyhole and Molten Pool Behaviour in High Power Laser Welding
,”
Trans. JWRI
,
30
, pp.
13
27
.
9.
Katayama
,
S.
,
Kawahito
,
Y.
, and
Mizutani
,
M.
,
2010
, “
Elucidation of Laser Welding Phenomena and Factors Affecting Weld Penetration and Welding Defects
,”
Physics Procedia
,
5
(
Part B
), pp.
9
17
.10.1016/j.phpro.2010.08.024
10.
Kawaguchi
,
I.
,
Tsukamoto
,
S.
,
Honda
,
H.
, and
Arakane
,
G.
,
2003
, “
Power Modulation in Deep Penetration Laser Welding-Optimization of Frequency and Waveform to Prevent the Porosity
,”
ICALEO
, LMP-Section A, pp.
168
175
.
11.
Norris
,
J. T.
,
Robino
,
C. V.
,
Hirschfeld
,
D. A.
, and
Perricone
,
M. J.
,
2011
, “
Effects of Laser Parameters on Porosity Formation: Investigating Millimeter Scale Continuous Wave Nd: YAG Laser Welds
,”
Weld. J.
,
90
, pp.
198
203
.
12.
Lee
,
J. Y.
,
Ko
,
S. H.
,
Farson
,
D. F.
, and
Yoo
,
C. D.
,
2002
, “
Mechanism of Keyhole Formation and Stability in Stationary Laser Welding
,”
J. Phys. D: Appl. Phys.
,
35
(
13
), pp.
1570
1576
.10.1088/0022-3727/35/13/320
13.
Zhou
,
J.
,
Tsai
,
H. L.
, and
Wang
,
P. C.
,
2006
, “
Transport Phenomena and Keyhole Dynamics During Pulsed Laser Welding
,”
ASME J. Heat Transfer
,
128
(
7
), pp.
680
690
.10.1115/1.2194043
14.
Zhao
,
H.
,
Niu
,
W.
,
Zhang
,
B.
,
Lei
,
Y.
,
Kodama
,
M.
, and
Ishide
,
T.
,
2011
, “
Modeling of Keyhole Dynamics and Porosity Formation Considering the Adaptive Keyhole Shape and Three-Phase Coupling During Deep-Penetration Laser Welding
,”
J. Phys. D: Appl. Phys.
,
44
(
48
), p.
485302
.10.1088/0022-3727/44/48/485302
15.
Pang
,
S.
,
Chen
,
L.
,
Zhou
,
J.
,
Yin
,
Y.
, and
Chen
,
T.
,
2011
, “
A Three-Dimensional Sharp Interface Model for Self-Consistent Keyhole and Weld Pool Dynamics in Deep Penetration Laser Welding
,”
J. Phys. D: Appl. Phys.
,
44
(
2
), p.
025301
.10.1088/0022-3727/44/2/025301
16.
Courtois
,
M.
,
Carin
,
M.
,
Le Masson
,
P.
, and
Gaied
,
S.
,
2013
, “
A Two-Dimensional Axially-Symmetric Model of Keyhole and Melt Pool Dynamics During Spot Laser Welding
,”
Rev. Métall.
,
110
, pp.
165
173
.10.1051/metal/2013060
17.
Yilbas
,
B. S.
,
1995
, “
Study of Liquid and Vapor Ejection Processes During Laser Drilling of Metals
,”
J. Laser Appl.
,
7
(
3
), pp.
147
152
.10.2351/1.4745388
18.
DeBastiani
,
D. L.
,
Modest
,
M. F.
, and
Stubican
,
V. S.
,
1990
, “
Mechanism of Material Removal From Silicon Carbide by Carbon Dioxide Laser Heating
,”
J. Am. Ceram. Soc.
,
73
(
7
), pp.
1947
1952
.10.1111/j.1151-2916.1990.tb05250.x
19.
Zeng
,
X.
,
Mao
,
X.
,
Mao
,
S. S.
,
Yoo
,
J. H.
, and
Greif
,
R.
,
2004
, “
Laser-Plasma Interactions in Fused Silica Cavities
,”
J. Appl. Phys.
,
95
(
3
), pp.
816
822
.10.1063/1.1635990
20.
Basu
,
S.
, and
DebRoy
,
T.
,
1992
, “
Liquid Metal Expulsion During Laser Irradiation
,”
J. Appl. Phys.
,
72
(
8
), pp.
3317
3322
.10.1063/1.351452
21.
Chan
,
C. L.
, and
Mazumder
,
J.
,
1987
, “
One-Dimensional Steady-State Model for Damage by Vaporization and Liquid Expulsion Due to Laser–Material Interaction
,”
J. Appl. Phys.
,
62
(
11
), pp.
4579
4586
.10.1063/1.339053
22.
Wallis
,
G. B.
,
1969
,
One-Dimensional Two-Phase Flow
,
McGraw-Hill
,
New York
.
23.
Hewitt
,
G. F.
,
1982
, “
Liquid-Gas Systems
,”
Handbook of Multiphase Systems
,
G.
Hetsroni
, ed.,
Hemisphere Pub.
,
New York
, Chap. 2.
24.
Ishii
,
M.
,
1982
, “
Wave Phenomena and Two-Phase Flow Instabilities
,”
Handbook of Multiphase Systems
,
G.
Hetsroni
, ed.,
Hemisphere Pub.
,
New York
, Chap. 2.4.
25.
Wei
,
P. S.
,
Wu
,
J. H.
, and
Chao
,
T. C.
,
2014
, “
Effects of Entrainment on Incapability of High Intensity Beam Drilling
,”
ASME J. Heat Transfer
(in press).10.1115/1.4029086
26.
Wei
,
P. S.
,
Chuang
,
K. C.
,
Ku
,
J. S.
, and
DebRoy
,
T.
,
2012
, “
Mechanisms of Spiking and Humping in Keyhole Welding
,”
IEEE Trans. Compon. Packag. Manuf. Technol.
,
2
(
3
), pp.
383
394
.10.1109/TCPMT.2011.2178412
27.
Wei
,
P. S.
, and
Chiou
,
L. R.
,
1988
, “
Molten Metal Flow Around the Base of a Cavity During a High-Energy Beam Penetrating Process
,”
ASME J. Heat Transfer
,
110
(
4a
), pp.
918
923
.10.1115/1.3250593
28.
Batteh
,
J. J.
,
Chen
,
M. M.
, and
Mazumder
,
J. A.
,
1999
, “
Coupled Stagnation Flow and Knudsen Layer Analysis for Laser Drilling
,”
ASME Publications HTD
,
364
(
3
), pp.
189
196
.
29.
Amara
,
E. H.
,
Fabbro
,
R.
, and
Bendib
,
A.
,
2003
, “
Modeling of the Compressible Vapor Flow Induced in a Keyhole During Laser Welding
,”
J. Appl. Phys.
,
93
(
7
), pp.
4289
4296
.10.1063/1.1557778
30.
Viskanta
,
R.
,
1988
, “
Heat Transfer During Melting and Solidification of Metals
,”
ASME J. Heat Transfer
,
110
(
4b
), pp.
1205
1219
.10.1115/1.3250621
31.
Reznichenko
,
V. F.
, and
Verigin
,
A. M.
,
1986
, “
Parameters of the Vapor-Gas Phase in the Channel in Deep Penetration of Metals With an Electron Beam
,”
Svar. Proizvod.
,
6
, pp.
25
28
.
32.
Poueyo-Verwaerde
,
A.
,
Fabbro
,
R.
,
Deshors
,
G.
,
de Frutos
,
A. M.
, and
Orza
,
J. M.
,
1993
, “
Experimental Study of Laser-Induced Plasma in Welding Conditions With Continuous CO2 Laser
,”
J. Appl. Phys.
,
74
(
9
), pp.
5773
5780
.10.1063/1.355284
33.
Collur
,
M. M.
, and
DebRoy
,
T.
,
1989
, “
Emission Spectroscopy of Plasma During Laser Welding of AISI 201 Stainless Steel
,”
Metall. Trans. B
,
20
(
2
), pp.
277
286
.10.1007/BF02825608
34.
Modest
,
M. F.
,
1993
,
Radiative Heat Transfer
,
McGraw-Hill
,
New York
.
35.
Shapiro
,
A. H.
,
1953
,
The Dynamics and Thermodynamics of Compressible Fluid Flow
, Vol.
2
,
Wiley
,
New York
.
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