MINION

In many industrial sectors it is necessary to combine materials due to the different requirements on e.g. deformability or also costs. Welding, as one of the oldest and established joining processes, shows itself to be very well suited, but depending on the material to be joined, it brings with it challenges in terms of parameters to be selected, process control, and the effects of the aforementioned on strength and corrosion resistance as well as cleanliness (in the sense of being particle-free). In particular, problems often arise in practice when joining dissimilar materials.

In this project, primarily shape memory alloys such as Nitinol are to be joined with stainless steels. In practice, this poses a major problem. Joining dissimilar materials is a particular challenge. The different physical properties, such as thermal conductivity, lattice structure and the formation of mixed phases and phase mixtures and their influence on the mechanical properties, make it difficult to achieve a defect- and crack-free joint when combining different materials. In addition, for the use of such material combinations, sufficient corrosion resistance must be maintained even after joining.
The aim of these investigations is to identify suitable parameters for joining components made of stainless steel and nitinol by electron beam welding. Not only should the mechanical properties of the joint meet the requirements, but the corrosion resistance of the joint should also be ensured.
One application in medical technology, for example, would be the material-locked joining of guide wires for the use of catheters. These fulfill the function of positioning treatment instruments as far as peripheral vessels. Another area of application is tools for drilling holes to attach tendons and ligaments to bones. In both applications, requirements such as static and dynamic strength, biocompatibility, corrosion resistance, cleanliness and X-ray visibility must be met.