Analysis of Fatigue Indicator Parameters for Ti-6Al-4V microstructures using extreme value statistics in the HCF regime

Abstract Fatigue Indicator Parameters (FIPs) have been introduced to serve as surrogate measures of driving force to form and grow fatigue cracks. With Ti-6Al-4V, we consider that transgranular cracks may form along slip bands due to irreversible cyclic plasticity or disruption of phase boundaries impinged by dislocation pile-up under mean stress. FIPs that capture these mechanisms are examined over several microstructure and loading conditions in the High Cycle Fatigue (HCF) regime. The peaks-over-threshold approach determines extreme FIP values and rank-orders fatigue behavior of microstructures. It is shown that fatigue crack formation is dominated by alpha-phase grains in the HCF regime.