Estimation of Friction under High Pressure-Application to High Pressure Tube Twisting (HPTT)

Severe Plastic Deformation (SPD) processes are used to obtain ultra-fine grain materials by achieving very high strain under hydrostatic pressure. The friction has to be very low in some process (ECAP) but very large for other (HPT, HPTT). Most of numerical analyses do not take in account the friction into the simulations. The contact is assumed to be sticked for HPTT processes. An experimental setup is presented to evaluate the coefficient of friction under high pressure. Numerical simulations are carried out to simulate the SPD process High Pressure Tube Twisting, the effect of the friction during the deformation and load requirement.