Edge ductility in TRIP steel

Duration

Start: 01-09-2018
End: 31-08-2022

Partners

Staff

Description

Advanced high strength steels (AHSSs) attracted a special attention from car industry with respect to their excellent formability and superior strength that results in higher car safety and less fuel consumption. However, the application of AHSSs is limited due to fracture at part edges at strains below those predicted by forming limit curves (FLCs). An FLC is a common and reliable method used for predicting forming behavior of sheet metals. An example of an edge crack during the forming process of a car body can be seen in Figure 1. Furthermore, the strain distribution during deformation of a DP (dual phase) steel with a sheared edge, measured by digital image correlation (DIC), is shown in Figure 2. It clearly shows the strain localization on edge. The current project in collaboration with TATA Steel aims to introduce an accurate method for measuring edge ductility. Subsequently, the edge fracture mechanism is investigated by microstructure analysis. Finally, a model that can predict accurately the fracture strain on edge during forming process is provided.


Figure 1: Edge cracks occuring during forming of a car body 

 

Figure 2: Evolution of strain distribution during bending deformation of AHSS shows strain localization on edge.