14
1 Laser Welding Basics
Plasma/metal vapor
cloud
Laser beam
Metal vapor flow
Weld pool
Marangoni
hydrodynamics
And flow of vapor
under pressure
Base metal
Heat
conduction
Laser
passing
through keyhole
Metal vapor cloud
Metal vapor flow
Fig. 1.4 Diagram of laser penetration welding principle
weld layout and slight thermal deformation caused by welding process, inevitably
affect the stability of welding process. Therefore, various complicated theoretical
and technical problems are exposed in the welding process. The first one is the
poor welding process stability and repeatability, such as frequent interruptions in
the welding process, which make it impossible to maintain a stable welding in the
whole process. The second one is that the generation mechanism of welding defects
is unclear, and the control technology is not well developed, which lead to negligible
advancement of laser welding. In addition, the performance of laser welding joint
is uneven with poor consistency, which makes the welded structure fail to meet the
demand for functions. These problems seriously affect the application and promotion
of laser welding technology.
1.3 Research on Weld Pool Behavior in Laser Welding
Compared with the conventional arc welding method, the deep penetration laser
welding, which is based on the theoretical basis of keyhole effect, has attracted wide
attention for its high energy density, low heat input, high depth-to-width ratio of
weld, small heat affected zone (HAZ), small deformation, high welding quality, high
production efficiency, flexible control, etc.
1 Laser Welding Basics
Plasma/metal vapor
cloud
Laser beam
Metal vapor flow
Weld pool
Marangoni
hydrodynamics
And flow of vapor
under pressure
Base metal
Heat
conduction
Laser
passing
through keyhole
Metal vapor cloud
Metal vapor flow
Fig. 1.4 Diagram of laser penetration welding principle
weld layout and slight thermal deformation caused by welding process, inevitably
affect the stability of welding process. Therefore, various complicated theoretical
and technical problems are exposed in the welding process. The first one is the
poor welding process stability and repeatability, such as frequent interruptions in
the welding process, which make it impossible to maintain a stable welding in the
whole process. The second one is that the generation mechanism of welding defects
is unclear, and the control technology is not well developed, which lead to negligible
advancement of laser welding. In addition, the performance of laser welding joint
is uneven with poor consistency, which makes the welded structure fail to meet the
demand for functions. These problems seriously affect the application and promotion
of laser welding technology.
1.3 Research on Weld Pool Behavior in Laser Welding
Compared with the conventional arc welding method, the deep penetration laser
welding, which is based on the theoretical basis of keyhole effect, has attracted wide
attention for its high energy density, low heat input, high depth-to-width ratio of
weld, small heat affected zone (HAZ), small deformation, high welding quality, high
production efficiency, flexible control, etc.