PCPLAS · Prediction and control of porosity in laser welding of non-ferrous metals

Laser welding is a robust process for producing full penetration welds in steels. Welds in non-ferrous materials (such as Al and Ti), achieving acceptable weld quality is less straightforward. Of particular concern is porosity formation in the deep penetration. Achieving low levels of porosity in a reproducible way is currently preventing acceptance of laser welding in the aerospace and to some extent, in the automotive industries, in spite of the economic and manufacturing benefits. The porosity problem in laser welds is well documented in published literature but it is often very difficult to compare the results. Recent developments in high brightness solid-state lasers such as Yb-fibre and Yb:YAG disc lasers increase the possibilities for laser welding in these fields. In comparison to the other lasers, the fibre laser represents a better beam quality, higher cost efficiency and more flexible integrated system with a promising future. There is very little results available using the latest high brightness lasers. There is a clear need for better understanding the beam-materials interactions when welding with these high brightness lasers.The objective of this project is to develop technical solutions for achieving high quality (low porosity) laser welds and to establish guideline for using fibre laser welding in non-ferrous metals including aluminium and titanium.The specific objectives are:1. To carry out numerical modelling to simulate the interactions between the laser beam and molten metaland to understand the formation of porosity in laser welds in non-ferrous metals;2. To develop monitoring techniques for direct observing the weld pool behaviours in laser welding andhybrid laser-MIG welding, using high speed camera;3. To establish the characteristics of plume formations during laser welding and to develop techniques foreffective suppression of plumes in laser welding;4. To produce recommendations for eliminating porosity in laser welded non-ferrous alloys