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 and magnesium. For high melting point alloys as steel, this industrialisation is still a wish but many achievements are reached 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, a lot of constitutive models have been proposed during the last years [1]. However, until now there are really few studies 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 to propose a quantification of the friction coefficients for the thixoforming technology thanks to experiments on a dedicated tool and comparison with finite elements simulations run on the code Forge2008©. The used friction law is a Coulomb limited Tresca one.