A method of quasi in-situ EBSD observation for microstructure and damage evolution in fatigue and dwell fatigue of Ti alloys

A method of quasi in-situ electron backscattered diffraction observation is developed for investigating microstructure and damage evolution of Ti-6Al-4V ELI alloy under cyclic loadings. It indicates that the slip tends to occur in & alpha; grains with bigger Schmid factors (SFs) for basal slip or prismatic slip and twinning occurs in & alpha; grains with SFs not bigger than 0.2 for prismatic slip for both fatigue and dwell fatigue. The plastic strain caused by dwell stress could restrain the sliding or cleavage induced microcrack growth. Subgrain formation in & alpha; grains due to twinning and dislocation sliding are also captured during cyclic loadings.

Automated summary

A quasi in-situ electron backscattered diffraction observation method was developed to investigate the microstructure and damage evolution of Ti-6Al-4V ELI alloy under cyclic loadings. The study reveals that slip tends to occur in α grains with bigger Schmid factors (SFs) for basal slip or prismatic slip, and twinning occurs in α grains with SFs not bigger than 0.2 for prismatic slip, both in fatigue and dwell fatigue. The plastic strain caused by dwell stress can restrain the sliding or cleavage-induced microcrack growth. Subgrain formation in α grains due to twinning and dislocation sliding is also observed during cyclic loadings.