The use of new ultra high strength steels in multi material joinings are a key factor for lightweight solutions in regards of BIW structure design. These new hot stamped steels reached up to 1800 MPa and are potentially combined with aluminium material in car body assemblies. Some of the current standard joining technologies are not capable to achieve these dissimilar joinings. By addition of a local heat treatment by laser, we can introduce softer areas in the steel and be able to use conventional joining processes like SPR or FDS.

5 key learning points in this session:
1. Ultra-high strength boron steels
2. Multi material joinings
3. Types of annealing of hot stamped steels
4. Local softening by laser
5. Proposal of alternative mechanical joinings