Friction coefficients evaluation for steel thixoforging

Since the first works on thixoforming, lot of studies have been performed all over the world and the
behaviour of the globular semi-solid slurry is now quite well understood. This knowledge had lead
to an industrialisation of the technology for low melting point alloys as aluminium or magnesium.
For high melting point alloys as steel, this industrialisation is still a wish but seems closer each year.
In the aim of this development of the process, it is important to be able to accurately represent the
behaviour of the slurry during thixoforming. In this goal, lot of constitutive models has been
proposed during the last years. However, until now there isn’t any study about the friction in the
case of thixoforming. This knowledge is needed as friction has an important effect on the flow of
the slurry during the shaping. The aim of this work is so to propose a quantification of the friction
coefficients for the thixoforming technology thanks to experiments on a dedicated tool and
comparison with simulations run on the finite elements code Forge2008©. The friction law is a
Coulomb limited Tresca one.