LAWALU - Towards Successful Laser Welding of Aluminium

Aluminium and its alloys are an important group of metallic alloys for modern industry. Norway being one of the largest aluminium producers in Europe should extend their application through innovative manufacturing processes such as advanced laser-based welding. Laser-based welding is a rapidly emerging joining process which is attractive for joining aluminium alloys providing a significant increase in productivity compared to conventional arc welding. Moreover, a large portion of expensive welding consumables can be saved providing reduced CO2 emission by a smart utilization of materials. Laser-based welding of thick plates operates in keyhole mode where a deep vapor filled cavity is formed due to highly concentrated energy of the focused beam. This enables much faster welding speeds and requires only a few passes even for thick plates. However, such deep capillary is quasi-stable and prone to instabilities, thus porosity and other imperfections can be easily formed. The project will provide an experimental framework for optimization of parameters aiming to reduce porosity levels to a minimum for qualification. Moreover, complex numerical models and in-situ monitoring systems will contribute to in-depth understanding of laser welding physics. The project will develop a design-based approach of aluminium structures to increase strength and fatigue under complex loads and be laser-friendly for improved manufacturing. Development of advanced process monitoring and detection systems will assist in improved automation to increase the quality of products and minimize scrap. The final aim of the project is the ability to demonstrate the potential of laser-based welding systems so that industrial partners can implement them into their production lines.

Aluminium is light, strong, durable and recyclable, which becomes more and more attractive for many industry sectors. The low density of aluminium, resulting in a high strength-to-weight ratio, makes it a favourable material for structures in a variety of applications, e.g., buildings, automotive, aerospace, helideck, living quarters and offshore and onshore wind etc. The increased use of aluminium in large structures will significantly contribute to achieving the Norway's new climate target: emissions to be cut by at least 55% by 2030 compared to the 1990 level. Despite its advantages, there are several challenges that limit the widespread use of aluminum in large structures, e.g., lacking efficient joining technology, poor weld quality and fatigue properties of aluminium structures and conservatisms in design. The LAWALU project will introduce an innovative laser welding technology that has been unanimously recognized by all partners as the future solution for aluminium structure production. The LAWALU project is designed to solve technical challenges associated with laser welding of aluminium, which is regarded as an energy efficient and economically viable solution for production of aluminium structures based on deep understanding of the aluminium business value chain and long-term collaboration between the participating industry partners. The R&D challenges that will be addressed in this project include 1) developing performance- and physics-based design principles for aluminium structures, 2) understanding of material-laser interactions and developing laser welding process parameters and 3) developing in-situ monitoring and quality control techniques. The planned innovation developed in LAWALU will result in 1) increased production efficiency and reduced cost, 2) improved product quality and structural performance, 3) a shift of design philosophy for aluminium structures.