Effect of density and pore morphology on fatigue properties of sintered Ti–6Al–4V

• We reported the correlation between sintered density and fatigue properties of P/M Ti–6Al–4V.
• We examined the correlation between pore morphology and fatigue properties of P/M Ti–6Al–4V.
• Shape factor was used to quantify the pore morphology of P/M Ti–6Al–4V.
• Stress concentration factor was calculated for different shape pores.

The fatigue properties of sintered Ti–6Al–4V were investigated as a function of sintered density and pore morphology. A quantitative analysis of microstructure was conducted to correlate with tensile and fatigue properties to understand the influence of sintered density and pore morphology. Low cycle fatigue (LCF) and high cycle fatigue (HCF) tests were conducted using two alloys with different sintered densities (95% and 99%). It was found that there was no significant difference in tensile strength but the fatigue endurance limit was increased by 20% when the sintered density was increased from 95% to 99%. Fracture surface analysis indicated that the fatigue cracks initiated from clusters of pores either at the surface or at the near sub-surface. The effect of pore morphology and porosity on mechanical behavior and fatigue fracture of P/M Ti–6Al–4V was quantified using the pore shape factor. It was found that specimens with a higher pore shape factor had a higher fatigue endurance limit.