Chapter 1
Laser Welding Basics
Abstract This chapter introduces the basics of laser welding process. The principles
of laser material interactions, the characteristics and theories of laser welding, and
the research outlines of weld pool dynamics of laser welding process are presented.
1.1 Interaction of Lasers and Materials
The interaction process between laser and material is complicated, involving multiple
disciplines such as laser physics, heat transfer, plasma physics, non-linear optics,
thermodynamics, gas dynamics, fluid mechanics, mechanics of materials, and solidstate physics. Laser welding, which is one of the major applications of the laser
processing technology, also utilizes the physical phenomenon generated by the interaction between laser and material, and these physical phenomena may come down
to the thermal and mechanical effect of the material being processed. The main
research content and direction include the reflection, absorption, and energy conversion of the laser by the material, and the heating, melting, thermocompression shock
wave, vapor ejection, plasma expansion, and shock wave of the material by the laser.
Nevertheless, during the laser welding research, the focus is on the absorption of the
laser by the welded material and the thermophysical and mechanical effects of the
material itself (such as heating, melting, vaporization, and plasma effect). The main
physical phenomena are shown in Fig. 1.1.
1.1.1 Laser Absorption by Materials and Material Heating
The regular motion of damped oscillation of the charged particles in the atom is
described by the classical mechanics; that is to say, the charged particles are regarded
as the oscillators following the classical mechanics. The oscillators vibrate as bound
close to a certain equilibrium position by the elastic restoring force directly proportional to the displacement. In case of deviating from the balanced position, the oscillators will be acted by a restoring force. In terms of metal, oscillators in the metallic
© 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_1
1
Laser Welding Basics
Abstract This chapter introduces the basics of laser welding process. The principles
of laser material interactions, the characteristics and theories of laser welding, and
the research outlines of weld pool dynamics of laser welding process are presented.
1.1 Interaction of Lasers and Materials
The interaction process between laser and material is complicated, involving multiple
disciplines such as laser physics, heat transfer, plasma physics, non-linear optics,
thermodynamics, gas dynamics, fluid mechanics, mechanics of materials, and solidstate physics. Laser welding, which is one of the major applications of the laser
processing technology, also utilizes the physical phenomenon generated by the interaction between laser and material, and these physical phenomena may come down
to the thermal and mechanical effect of the material being processed. The main
research content and direction include the reflection, absorption, and energy conversion of the laser by the material, and the heating, melting, thermocompression shock
wave, vapor ejection, plasma expansion, and shock wave of the material by the laser.
Nevertheless, during the laser welding research, the focus is on the absorption of the
laser by the welded material and the thermophysical and mechanical effects of the
material itself (such as heating, melting, vaporization, and plasma effect). The main
physical phenomena are shown in Fig. 1.1.
1.1.1 Laser Absorption by Materials and Material Heating
The regular motion of damped oscillation of the charged particles in the atom is
described by the classical mechanics; that is to say, the charged particles are regarded
as the oscillators following the classical mechanics. The oscillators vibrate as bound
close to a certain equilibrium position by the elastic restoring force directly proportional to the displacement. In case of deviating from the balanced position, the oscillators will be acted by a restoring force. In terms of metal, oscillators in the metallic
© 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_1
1