Speaker
Description
The usage of multi material design in modern vehicles and particular in the body in white (BIW) production is steadily rising to fulfil demands of emission laws and conservation of resources. Besides the conservative joining methods for a multi material design (e.g. screws and rivets) the well-known hybrid casting with steel inserts and aluminium can be used with the advantage of reducing the additional joining operations and therefore to reduce the costs and cycle times in the production itself.
The process of hybrid casting is normally applied on non-structural parts where a force or form locking is enough for the life cycle of the component and the desired properties. In order to achieve a high performance material based bonding between the steel inserts and the aluminium cast components for body or chassis structures, a novel physical vapour deposition (PVD) Al-Si coating was developed and applied.
The applied Al-Si PVD coating on the steel insert inhibits the growth of brittle Al-Fe intermetallic phases in-between the components. Several casting trials (low pressure sand casting and high pressure die casting) were done with different casting parameters. Shear tensile strengths of 10 to 13 MPa were measured on simple overlap geometries.
Combined SEM and EBSD analysis showed, that the PVD coating is acting like a bonding agent in-between the steel insert and the aluminium cast. Cross-section analyses predict a fracture of the interfacial area of the coating and the aluminium cast. Nonetheless, a ductile mechanical behaviour can be observed due to the honeycomb like structures on the fracture surfaces. Additional EDX analyses of the surfaces are showing only aluminium and silicon signals, which are contributing to the failure mechanism, that the bonding is breaking in-between the coating and the aluminium cast.
| Speaker Country | Germany |
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