The progressive development in additive manufacturing of metals creates new opportunities in the design of automotive components. At current stage, there is still a lack of large-scale use due to missing qualification and validation of materials according to automotive requirements. Furthermore, the currently processed LAM aluminium alloys are only limited capable for the use in high stressed applications. Hence, the development of a new aluminium alloy is ongoing along with the approval process for metals focusing on crash, joining, corrosion and fatigue strength. Due to the alloy composition (Al-Mg-Si based) and different heat treatment strategies, the manufacturing of high strength components as well as crash relevant body-in-white parts (high ductility) is possible.
Main aspects of the development are validated and reproducible mechanical properties, the characterisation and simulation of the material behaviour in the elastic and plastic range up to failure and the joining (bonding and riveting) of additive and conventional manufactured components.
The basic mechanical properties were analysed in quasi-static tensile and bending tests (a). Based on these results, shear and notched tension tests under quasi-static conditions, high dynamic tensile tests and compression tests were performed.
This work investigates the influence of triaxiality on damage behaviour, the strain rate sensitivity (strain rates from 0.0047 to 250s-1) and the deformation behaviour of tubes and joined top-hat profiles.
The findings show reproducible material characteristics with minor anisotropy and moderate strain rate sensitivity. Due to adjusted annealing temperatures (T<500°C) and treatment times (t<120min), steady deformation characteristics and high deformation rates can be reached.
The deformation characteristics of the structures can be simulated using appropriate material and damage models and are in good agreement with the tensile, bending and compression tests. The integration of additive manufactured parts into existing structures can be ensured by bonding and riveting with comparable joining qualities to their conventional counterparts.
(a) Content is in relation with the submission of Mr. Knoop / Mr. von Hehl (IWT Bremen) for the LightMAT Conference 2019 and contains the gradual continuation of the developmental work.