Product Code: ICA11_604

Recent Developments in Laser Joining of Dissimilar Materials
Authors:
Claus Thomy, BIAS- Bremer Institut fur Agewandte Strahltechnik GmbH; Bremen Germany
Frank Vollertsen, BIAS- Bremer Institut fur Agewandte Strahltechnik GmbH; Bremen Germany
Presented at ICALEO 2011

Currently, the use of hybrid structural elements from dissimilar materials is intensively discussed. Primary aim is to reduce weight and maintain or increase mechanical properties and structural performance. In special, the joining of aluminium to steel is of particular interest for the transportation industries such as car production or shipbuilding. So far, a wide variety of laser- and arc-based processes was investigated for the production of structural joints in these industries. These developments are briefly reported and discussed in the paper. It will be concluded that all these processes up to now are characterised by various disadvantages such as relatively low processing speed, insufficient gap bridging or poor joint properties. The suggested solution in this context is laser arc hybrid welding.

On the basis of a detailed description of the process, significant correlations between process parameters and joint properties are reported and discussed and will be applied to the development of process parameter envelopes for joining of aluminium to steel at elevated joining speed exceeding 6 m/min in the thin sheet range. The joints obtained were characterised with respect to microstructure (SEM, EDX, EBSD), mechanical properties (strength and formabi) and corrosion. On this basis, results from application studies will be reported and discussed.
As an outlook, results from recent work on laser joining of aluminium to composites, intermetallic phase layer formation as a function of the time-temperature cycle of the joining process and the FE modelling of joint strength will be reported.