Determination of the friction factor of Ti-6Al-4V titanium alloy in hot forging by means of ring-compression test using FEM

► The hot ring-compression experiment was conducted at the height reductions of 30% and 50%. ► A 3D coupled thermo-mechanical FE model for ring-compression of Ti-6Al-4V alloy has been developed. ► The effects of heat-transfer coefficient on the friction and metal flow are significant. ► The neutral layer is not a line in cross-section but a curve, and its position is changeable. ► The friction coefficients of Ti-6Al-4V alloy with glass lubricant and dry condition are determined.