Hybrid laser-arc welding is a joining process simultaneously combining laser welding and arc welding in the same weld pool. In theory, the beam from any welding laser source (CO2 , Nd:YAG, diode, Yb fibre, Yb:YAG disk etc) can be combined with any arc process (MIG/MAG, TIG, SAW, plasma). Typically, however, hybrid laser-MIG/MAG and laser-TIG are the most common combinations for hybrid laser arc welding processes.
Hybrid laser arc welding requires high power lasers and a high-quality beam for deep penetration, especially when welding thick materials.
However, as a hybrid process, it has the individual advantages of both arc and laser welding processes. Deep penetration hybrid welds can be made, comparable with the penetration depths achieved by laser welds but, at the same time, having a tolerance to joint fit-up and a weld cap profile more comparable with arc welds. Furthermore, arc welding consumables (and gas mixtures) can be used, offering a degree of control over weld quality and properties than is possible with autogenous laser welding.
Example Applications
Hybrid welding is already being used, or under consideration, by the following industries:
- Road transport – the high welding speed of the hybrid process is attractive to the high production volume environments found in the automotive industry, especially given the greater part fit-up tolerance than with autogenous laser welding
- Shipbuilding – the lower heat input and distortion introduced when hybrid welding, when compared with MAG welding or SAW, reduces the costs associated with distortion correction and rework. By contrast, conventional arc welding methods and their associated re-work have been estimated to constitute up to 20-30% of overall manufacturing costs
- Rail transport – as in shipbuilding, the low distortion that can result from hybrid railcar seam welding, compared with conventional arc welding processes, is of interest as a means of reducing fabrication costs, as well as the high productivity welding speeds, which reduce overall welding time
- Oil and gas – the hybrid welding of pipes has been well demonstrated, and with continuing developments in laser sources and pipe steels, continues to be of interest as a future means of increasing overall joint completion rates, depending on steel grades used and operating environment requirements
Advantages of Hybrid Laser Arc Welding
The chief benefits of hybrid laser-arc welding include:
- Improved tolerance to joint fit-up; for example, hybrid welding can extend the tolerance to joint gap by a factor of at least 2-3 times over laser welding, or greater, if real-time adaptive control of hybrid welding parameters is carried out
- Improved weld quality; hot cracking (e.g. in some higher strength Al alloys) can be avoided, and internal porosity content reduced, with respect to laser welds
- Increases in single pass penetration depth; this is controlled principally by the choice of laser and welding parameters used, but single pass penetrations >6-12mm can be achieved using higher power (≥5kW) lasers
- Increases in welding speed; this is also dependent on the laser used and materials being welded, but high speeds of >5m/min can be possible in thinner materials
- Reduced Distortion; Reducing the net heat input can result in lower distortion, rendering hybrid welding of particular interest for the making of long seam welds between plates and sections, or for the welding of attachments, etc.
Combining arcs and lasers, hybrid laser arc welding can offer the benefits of both techniques. The increases in penetration depth and/or welding speed, when compared with arc welding, are particularly significant, while the use of filler wire can help improve control and thereby produce higher quality welds than with autogenous laser beam welding.