Applications for which filler wire is added during laser welding include:
- Improve the joint fit-up tolerance (air gaps, mismatch, etc.) of the parts to be welded.
- Eliminate solidification cracking during welding. For some aluminum alloys wire is used to replace the low melting temperature alloys and reduce the freezing point during cooling. For welding 6XXX series aluminum alloys, high silicon content wire such as 4043 or 4047 leads to reduced cracking and improved mechanical properties of these weld.
- Modify the chemical composition or the microstructure of the weld metal to obtain suitable mechanical properties.
- Improve the weld profile such as to avoid undercut at the top and bottom bead. Excessive undercut can act as stress raiser, which can reduce the mechanical properties of the weld during the service.
Laser welding with filler wire is a multi-parameter process. Several laser and filler wire parameters influence weld quality. For information about optimizing laser welding process parameters that use filler wire, read “Developing Processes for Laser Welding with Wire Feed“.