The role of crack origin size and early stage crack growth on high cycle fatigue of powder metallurgy Ti-6Al-4V alloy

In this work, fatigue failure mode, crack initiation, and early stage crack growth mechanism in Ti-6Al-4V alloys with different levels of microstructural inhomogeneity were investigated. The quantitative correlations between fatigue life, crack origin size, and early stage short crack growth, were analyzed and discussed. The interior early stage short crack growth rate was determined to be 10−12-10−10 m/cycle. The high and very high cycle fatigue lives predicted based on crack initiation site size and early stage short crack growth rate agree well with real fatigue data.