| dc.description | The demand for hot stamped components has been growing in structural vehicle applications, due
to the advantages of combining lightweight design and safety improvement. Boron-manganese
22MnB5 steel is the most common grade for hot stamping applications. After the thermomechanical
process, the steel exhibits up to 1,500 MPa of tensile strength with the absence of the
springback effect. The hot stamping process involves heating the steel blank to the austenitization
temperature and then transferring it from the furnace to the press tool, where the material is formed
and quenched simultaneously. Due to high temperatures during the process, the steel blank is
protected with a metallic coating to avoid the steel decarburization and oxidation. Hot-dip Al-Si is
the most applied coating system on boron-manganese steel for hot stamping applications. It is
known that, during hot stamping, diffusion takes place changing the coating layer morphology. The
objective of this study is to investigate the effect of the hot stamping process on the
electrochemical behaviour of 22MnB5 steel coated with hot-dip Al-Si by means of the SKPFM
technique. Moreover, the samples were characterized by means of FE-SEM/EDS. The SKPFM
results showed that, before the hot stamping process, there is a high difference of potential
between the coating layer and the steel substrate. After hot stamping, this difference decreases. In
both conditions (before and after hot stamping), the coating layer is less noble than the steel
substrate. It was also observed that the steel substrate potential also decreased after the hot
stamping process. This could be a consequence of iron diffusion towards the coating layer and the
recrystallization of the substrate after the thermo-mechanical process. | |
