230
8 Keyhole and Weld Pool Dynamics in Laser Welding with Filler Wires
Table 8.8 Technical
parameters of laser welding
Laser
power/kW
Laser spot
radius/mm
Defocusing
amount/mm
Welding
speed/
(m/min)
2
0.3
0
2
single-beam laser welding and welding with filler wire may be obtained. However,
due to current limited computer capabilities, it is difficult to obtain, by calculation in
a reasonable time based on the above method, a moving weld pool that reaches the
quasi-steady state.
Therefore, in this section, a model proposed by the authors is used to obtain a
quasi-steady moving weld pool. In this model, the formation process of keyholes
and the formation process of moving weld pools are considered separately; when
a keyhole is formed, it is solidified, and the wall temperature of the keyhole is
fixed to the evaporation temperature, and then the quasi-steady moving weld pool
is calculated by taking into account the thermal capillary force and other factors.
The calculation speed may be greatly improved in this way. Although it can be seen
from the existing research conclusions that this simple model cannot fully reflect
the transient nature of laser welding process, it can still increase our understanding
of the dynamic dilution process behavior of the moving weld pool by studying the
behavior of the chemical compositions of the wire in this quasi-steady moving weld
pool.
The technical parameters used in the laser welding process are shown in Table
8.8. The parent metal is Ti–Al alloy and the wire is Al-Si alloy. The contents of the
chemical compositions of the two materials are shown in Table 8.9 and Table 8.10
respectively. Table 8.11 shows the thermophysical properties of the parent metal.
Table 8.9 Chemical compositions of parent metal
Al
V
Ni
Bi
H
Ti
6
4
2
7
0.1
Equilibrium state
Table 8.10 Chemical compositions of wire
Si
Mn
Ti
O
Al
20
8
10
0.2
Equilibrium state
Table 8.11 Thermophysical parameters for parent metal
Density
/(kg/m 3 )
Specific
heat
capacity
/[J/(kg•K)]
Thermal
conductivity
/[W/(m•K)]
Liquidus
temperature/K
Solidus
temperature/K
Latent
heat of
melting
/(J/kg)
Latent heat
of
evaporation
/(J/kg)
Boiling
point
/K
4000
660
25
1928
1878
3.7 ×
10 5
8.9 × 10 6
3315
8 Keyhole and Weld Pool Dynamics in Laser Welding with Filler Wires
Table 8.8 Technical
parameters of laser welding
Laser
power/kW
Laser spot
radius/mm
Defocusing
amount/mm
Welding
speed/
(m/min)
2
0.3
0
2
single-beam laser welding and welding with filler wire may be obtained. However,
due to current limited computer capabilities, it is difficult to obtain, by calculation in
a reasonable time based on the above method, a moving weld pool that reaches the
quasi-steady state.
Therefore, in this section, a model proposed by the authors is used to obtain a
quasi-steady moving weld pool. In this model, the formation process of keyholes
and the formation process of moving weld pools are considered separately; when
a keyhole is formed, it is solidified, and the wall temperature of the keyhole is
fixed to the evaporation temperature, and then the quasi-steady moving weld pool
is calculated by taking into account the thermal capillary force and other factors.
The calculation speed may be greatly improved in this way. Although it can be seen
from the existing research conclusions that this simple model cannot fully reflect
the transient nature of laser welding process, it can still increase our understanding
of the dynamic dilution process behavior of the moving weld pool by studying the
behavior of the chemical compositions of the wire in this quasi-steady moving weld
pool.
The technical parameters used in the laser welding process are shown in Table
8.8. The parent metal is Ti–Al alloy and the wire is Al-Si alloy. The contents of the
chemical compositions of the two materials are shown in Table 8.9 and Table 8.10
respectively. Table 8.11 shows the thermophysical properties of the parent metal.
Table 8.9 Chemical compositions of parent metal
Al
V
Ni
Bi
H
Ti
6
4
2
7
0.1
Equilibrium state
Table 8.10 Chemical compositions of wire
Si
Mn
Ti
O
Al
20
8
10
0.2
Equilibrium state
Table 8.11 Thermophysical parameters for parent metal
Density
/(kg/m 3 )
Specific
heat
capacity
/[J/(kg•K)]
Thermal
conductivity
/[W/(m•K)]
Liquidus
temperature/K
Solidus
temperature/K
Latent
heat of
melting
/(J/kg)
Latent heat
of
evaporation
/(J/kg)
Boiling
point
/K
4000
660
25
1928
1878
3.7 ×
10 5
8.9 × 10 6
3315