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Contents
7.4.1 Stability Mechanism of Dual-Beam Welding . . . . . . . . . . . . . 194
7.4.2 Influence of Process Parameters on Stability
of Dual-Beam Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195
7.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200
8 Keyhole and Weld Pool Dynamics in Laser Welding with Filler
Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
8.2 Multiphase Transient Coupling Model in Laser Welding
with Filler Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204
8.2.1 Mathematical Model of Wire Melting . . . . . . . . . . . . . . . . . . . 204
8.2.2 Transient Coupling Model of Keyhole and Weld Pool . . . . . 206
8.2.3 Boundary Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
8.3 Keyhole and Weld Pool Dynamics in Welding with Filler Wires . . . 208
8.3.1 Behaviors of Transient Keyholes and Weld Pools
Under Free Transition Conditions . . . . . . . . . . . . . . . . . . . . . . 208
8.3.2 Influences of Wire Feed Speed on Transient Keyhole
and Weld Pool Behaviors in Free Transition . . . . . . . . . . . . . . 211
8.3.3 Influences of Wire Diameter on Transient Keyhole
and Weld Pool Behaviors in Free Transition . . . . . . . . . . . . . . 213
8.3.4 Transient Keyhole and Weld Pool Behaviors Under
Contact Transition Conditions . . . . . . . . . . . . . . . . . . . . . . . . . 215
8.3.5 Influences of Wire Feed Speed on Transient Keyhole
and Weld Pool Behaviors in Contact Transition . . . . . . . . . . . 218
8.3.6 Influences of Wire Diameter on Transient Keyhole
and Weld Pool Behaviors in Contact Transition . . . . . . . . . . . 219
8.3.7 Comparison of Transient Keyhole and Weld Pool
Behaviors in Free Transition with Those in Contact
Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221
8.4 Instability of Keyhole and Weld Pool in Welding with Filler
Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223
8.4.1 Weld Pool Dynamics in Single Beam Laser Welding
and Laser Welding with Filler Wires . . . . . . . . . . . . . . . . . . . . 223
8.4.2 Weld Pool Dynamics in Welding with Filler Wires
Under Different Wire Feed Speeds . . . . . . . . . . . . . . . . . . . . . 225
8.4.3 Mechanism of Keyholes Instability in Welding
with Filler Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 226
8.5 Dynamic Dilution Behavior of Moving Weld Pools
in Welding with Filler Wires . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227
8.5.1 Model of Dilution in Weld Pools . . . . . . . . . . . . . . . . . . . . . . . 227
8.5.2 Dynamic Dilution Behavior in Quasi-Steady Weld
Pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
8.5.3 Dynamic Dilution Behavior in Transient Weld Pools . . . . . . 241
8.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250