Tribological behaviors between commercial pure titanium sheet and tools in warm forming

The tribological conditions between tools and sheet are the major factors affecting the product quality, forming limits and service life of tools in thin-walled titanium components warm forming. Using the orthogonal design based twist compression test in the temperature range of 25-300 °C, the significant factors affecting the coefficient of friction (CoF) and the influencing rules in CP-3 titanium sheet warm forming are clarified and discussed by changing tribological conditions such as tool material, lubrication, temperature and normal pressure. The results show that the significant factors affecting the CoF are lubrication, surface roughness, tool material, sliding velocity, normal pressure and temperature; compared with unlubricated condition, the graphite and MoS₂ greatly improve the friction condition and the maximum reduction of the CoF is 0.318; the CoFs of Cr12MoV/CP-3 and QAl10-3-1.5/CP-3 tribo-pairs show a similar tendency: the CoFs increase with increasing surface roughness and sliding velocity, and increase firstly then decrease with increasing normal pressure and temperature.