Hybrid laser-arc welding combines arc and laser welding in the same weld pool. In theory, any laser and arc welding sources can be used but the process is typically performed with laser-MIG/MAG and laser-TIG. Whichever sources are used, the process requires high power lasers with a high-quality beam for deep penetration, especially for joining thick materials.
Hybrid laser-arc welding delivers the advantages of both arc and laser welding. Capable of making deep penetration welds that are comparable to those made with laser welding, but with a tolerance to joint fit-up and a weld cap profile comparable to arc welds. Because arc welding consumables and gas mixtures can be used, there is a greater degree of control over the weld quality and properties than is possible with autogenous laser welding.
TWI has undertaken a number of projects related to hybrid laser arc welding over the decades, progressing the process for the benefit of our Industrial Members with new innovations and developments.
Core Research Programme (CRP) Projects
The TWI Core Research Programme is designed to allow us to undertake projects of interest to our Industrial Members, including several related to hybrid laser-arc welding.
- CO2/Yb Fibre Laser and Hybrid Laser-TIG Welding Processes
Originally proposed in the late 1970s, hybrid laser-arc welding gained increased interest from industry due to benefits such as high productivity, improved weld quality and lower cost than laser welding. Although it saw use in the shipbuilding and automotive industries, primarily to weld C-Mn steels, there were still several materials and process combinations to develop. This CRP project investigated laser-TIG and Yb fibre laser-TIG hybrid welding processes in comparison to autogenous laser welding of thick section (=10mm) austenitic stainless steel.
- Study of the Process Interactions During Hybrid Nd:YAG Laser-MIG/MAG Welding
Although hybrid laser-arc welding provided several potential benefits compared with laser and conventional arc welding, there was still a need for a true understanding of the interaction between the two processes. In order to optimise hybrid laser-arc welding, it was necessary to understand the parameters of both processes and how they work together. This includes the metal transfer of the filler wire in MIG/MAG welding and the behaviour of the arc and the keyhole. TWI initiated a study, through the CRP, to gain a better understanding of the interactions between the Nd:YAG laser keyhole and the MIG/MAG arc and to maximise the (industrial) potential of the process over Nd:YAG and MIG/MAG welding. Our experts not only investigated laser-arc interactions for different metal transfer modes but also determined the process stabilisation mechanism and the influence of processing conditions on hybrid Nd:YAG laser - MIG/MAG process stability, including process configuration, process separation and laser power.
- Hybrid Laser-Arc Weld Quality Enhancement
High quality laser welds are reliant on precise workpiece fit-up and accurate alignment between the laser beam and the joint line. This is made easier with the use of a sensor and control system that is capable of automatically measuring the joint characteristics and providing feedback to compensate for joint fit-up variations. TWI’s experts developed hybrid welding with adaptive control using a high brightness laser alongside sensing and control technologies. We developed hybrid butt welding procedures for 6mm thickness laser cut EN 1.4301/AISI 304 stainless steel plates, resulting in the first known instance of the adaptive control of more than one welding parameter simultaneously during the hybrid welding of stainless steels, more than doubling fit-up tolerances. Furthermore, we showed that the concepts demonstrated in this project could be applied equally to other fusion weldable materials, in other thicknesses, with other welding processes and with other joint configurations, following the appropriate selection of equipment and development of welding procedures.
- Hybrid Laser-MIG Welding of Aluminium Alloy Butt Joints
Also investigating joint fit-up tolerances and the use of a joint tracking sensor with feedback control for real-time measurement of joint gap and mismatch, this CRP project aimed to further develop hybrid laser-MIG welding with adaptive control. 5083 aluminium alloy was welded, representing a more fusion-weldable alloy used in shipbuilding and other surface transport industries, given its corrosion resistance and moderate strength. In particular, higher speed flat (PA) position butt welding of 4mm thickness wrought plate with adaptive control was addressed, as was pertinent to future light weighted applications.