An investigation of forming of Ti-6Al-4V at lower temperatures

Abstract. Forming components of titanium alloys via superplastic forming at elevated temperatures while being exposed to oxygen leads to surface oxidation. The hard oxide layer formed on the surface of components is referred to as the alpha case. This alpha case layer requires post-form processing to remove it, thus increasing overall manufacturing costs and times. Superplastic forming at lower temperatures can significantly reduce the formation of the alpha case and has other benefits, such as life extension of tooling and less energy consumption. This paper shows the work done in terms of forming non-commercial components at temperatures significantly lower than the traditional ones, proving that forming at those temperatures is readily achievable. Forming pressures and tonnage need to be readjusted because of the increase in the flow stresses of the material. This paper also illustrates the implementation of a microstructural-based model to predict the hot forming behaviour of commercial titanium alloy Ti-6Al-4V (Ti64) during forming at 800°C. The material model is implemented into a commercial finite element software, Abaqus, and PAM-STAMP to obtain the optimal pressure cycle to form a non-commercial research component at 800 °C with a view to minimizing alpha case formation.