Chapter 4
Simulation of Transient Keyhole
and Weld Pool
Abstract This chapter introduces the three-dimensional transient keyhole and weld
pool dynamics simulated by using the self-consistent laser keyhole welding model.
Transient keyhole dynamics and its physical characteristics as a function of welding
parameters are presented. Transient weld pool dynamics under a stable keyhole as
well as an unstable keyhole condition are also characterized by high resolution numerical simulations. The influence of physical factors such as multiple Fresnel reflections, thermophysical parameters and welding parameters on the coupled keyhole
and weld pool dynamics are presented.
4.1 Introduction
In deep penetration laser welding, the shape and temperature of the keyhole change
in real time with obvious instantaneity, even in the quasi-steady phase. At the same
time, the keyhole and its surrounding metal liquid extend forward with the movement of the laser heat source, while the weld pool sees drastic and complex heat
transfer and flow and phase shift. At present, it is difficult to quantitatively observe
and understand the dynamics of the transient keyhole and moving weld pool by
applying the test method. Therefore, based on the effective mathematical model of
laser welding, the quantitative visual simulation analysis in this process can promote
the understanding of the physical process of laser welding and provides guidance on
the welding process.
In this chapter, we take the fiber laser welding of aluminum alloy as the research
object, and conduct numerical simulation research on the dynamics of the transient
keyhole and moving weld pool, as well as its mechanism based on the sharp model
of laser welding described in Chap. 3. By making use of the generally accepted
literature result and high-speed camera CCD test result, we at first conduct verification calculation on the sharp interface model of laser welding established in the laser
welding process, and analyze and discuss the dynamics features of transient coupling
of keyhole and weld pool. Then, we systematically discuss the impact of different
physical factors (recoil pressure, surface tension, thermal capillary force and multiple
reflections and absorptions), different thermophysical parameters (heat conductivity
© China Aviation Publishing & Media Co., Ltd. 2021
S. Gong et al., Weld Pool Dynamics in Deep Penetration Laser Welding,
https://doi.org/10.1007/978-981-16-0788-2_4
107
Simulation of Transient Keyhole
and Weld Pool
Abstract This chapter introduces the three-dimensional transient keyhole and weld
pool dynamics simulated by using the self-consistent laser keyhole welding model.
Transient keyhole dynamics and its physical characteristics as a function of welding
parameters are presented. Transient weld pool dynamics under a stable keyhole as
well as an unstable keyhole condition are also characterized by high resolution numerical simulations. The influence of physical factors such as multiple Fresnel reflections, thermophysical parameters and welding parameters on the coupled keyhole
and weld pool dynamics are presented.
4.1 Introduction
In deep penetration laser welding, the shape and temperature of the keyhole change
in real time with obvious instantaneity, even in the quasi-steady phase. At the same
time, the keyhole and its surrounding metal liquid extend forward with the movement of the laser heat source, while the weld pool sees drastic and complex heat
transfer and flow and phase shift. At present, it is difficult to quantitatively observe
and understand the dynamics of the transient keyhole and moving weld pool by
applying the test method. Therefore, based on the effective mathematical model of
laser welding, the quantitative visual simulation analysis in this process can promote
the understanding of the physical process of laser welding and provides guidance on
the welding process.
In this chapter, we take the fiber laser welding of aluminum alloy as the research
object, and conduct numerical simulation research on the dynamics of the transient
keyhole and moving weld pool, as well as its mechanism based on the sharp model
of laser welding described in Chap. 3. By making use of the generally accepted
literature result and high-speed camera CCD test result, we at first conduct verification calculation on the sharp interface model of laser welding established in the laser
welding process, and analyze and discuss the dynamics features of transient coupling
of keyhole and weld pool. Then, we systematically discuss the impact of different
physical factors (recoil pressure, surface tension, thermal capillary force and multiple
reflections and absorptions), different thermophysical parameters (heat conductivity
© China Aviation Publishing & Media Co., Ltd. 2021
S. Gong et al., Weld Pool Dynamics in Deep Penetration Laser Welding,
https://doi.org/10.1007/978-981-16-0788-2_4
107