Title:
MODELLING OF THE EFFECTS OF FRICTION ON BULK DEFORMATION BEHAVIOUR DURING DROP-FORGING OF AA7075

Authors:
W. Tetlow, R.P. Turner, United Kingdom

Abstract:

Aluminium alloy 7075 components are commonplace in the aerospace industry due to their high strength: density ratio. The investigation of the effects of friction during drop forging on the mechanical properties, thermal properties, and grain size of the finished product is carried out and analysed using finite element (FE) modelling. Three different coefficients of friction are simulated, and three different starting soak temperatures simulated in order to predict results across a variety of industrial conditions. The coefficient of friction is predicted to not have a marked effect on grain size and thus mechanical properties of the component - the strengthening is attributed to shear bands and the formation of nanograins. A higher coefficient of friction of 0.7 is predicted to inhibit the material flow of the billet over the die, thus increasing forging time and production cost unnecessarily. Whereas, a low coefficient of friction of 0.12 is predicted to cause high residual stresses as the billet wants to deform around sharper tooling edges during the forging process, with these corners acting as stress raiser locations. This resulted in stress values predicted to approach the tensile strength of AA7075.