Nowadays the protection of the climate and a resource-conserving acting is more important then ever before. In this context, a reduction of fuel consumption, hence a reduced CO2 emission is demanded from automobiles. That requires, among other things, a decreased vehicle weight. One way to fulfill this, is the use of lightweight body concepts through the application of high-strength steels, which allow thinner metal sheets, thus a reduction in weight.
At this point, a specific adjustment of the material properties plays a crucial role. The combination of hard and ductile regions within one component provides simultaneously good energy absorption in case of a crash and reliable passenger protection.
Our focus is on the development of suitable heat treatments and forming strategies to obtain the desired distribution of properties. In certain ductile areas of the components, a strength of ca. 600 to 700 MPa, under a fracture strain of 10 to 15 %, can be achieved. At the same time, the strength can be adjusted to more than 1500 MPa in other areas of the component.
Modern computer supported simulations and investigative methods are the basis for the adjustment of the desired properties of the components. In this way, the required temperature profile for local areas is determined. The different temperature profiles and the resulting distribution of properties within the component can be integrated as a step into the thermal forming process of high strength steels. Another possibility of adjusting the component properties is a local heat treatment before or after cold working of high-strength steels. These procedures can be performed on the machines developed by NMB. For this purpose, NMB has an oven-free hot forming production line and a high-performance induction-generator available.
- Investigation of process parameters to adjust specific material properties
- Forming tests at the hot forming production line
- Mechanical characterization of components with gradual properties