Advanced Welding Processes: Technologies and Process Control

8.1 Introduction
Advances in the high-energy processes, high-current plasma, electron beam
and laser welding, have been concerned with the application of the technology
to the fabrication of engineering materials. The power density of these processes
is significantly higher than that of the common arc welding processes [143]
and normally above 10 9 W m –2 ; typical values are compared in Fig. 8.1. As
a consequence of the high energy concentration, the mechanism of weld pool
formation is somewhat different from that normally found in other fusion
welding processes. The material in the joint area is heated to very high
temperatures and may vaporize, a deep crater or hole is formed immediately
under the heat source and a reservoir of molten metal is produced behind this
1.000E+15
1.000E+14
1.000E+13
1.000E+12
1.000E+11
1.000E+10
1.000E+09
1.000E+08
1.000E+07
1.000E+06
1.000E+05
136
Power density (W m –2 )
Vaporisation
Vaporisation, conduction
melting (keyholes)
8
High-energy density processes
Negligible melting
Radial conduction
with melting
GTAW/GM/AW Plasma YAG laser CO 2 laser electron beam
process
8.1 Comparative power density of various welding processes. [143,
144]