Pore evolution during thermomechanical processing of sintered Pure Ti

Pores in sintered pure titanium are generally considered as defects and detrimental to mechanical properties such as strength and fatigue resistance. A number of approaches have been developed to eliminate pores prior to, during and post sintering. In particular, forging, as an effective technique to reduce porosity by imposing material flow, has been widely used in both industrial applications and scientific studies. The pre-existing pores can apparently be "closed" by forging. However, due to insufficient temperature and time during forging, these "closed" pores with weak bonding between the surfaces may be re-opened under some circumstances, posing potential dangers in service. In this presentation, the evolution of pores during thermomechanical processing of sintered pure titanium will be described and the mechanisms explored based on the results obtained from a series of carefully designed experiments.