Role of Microtexture on the Fatigue Behavior of an alpha + beta Titanium Alloy, Ti-6Al-2Sn-4Zr-6Mo (Preprint).

摘要

The effect of microstructural heterogeneity, specifically regions of grains with similar crystallographic orientations, or microtexture, on the initiation and early growth of fatigue cracks from multiple micro-notches has been investigated in Ti-6246. Experiments were performed using ultrasonic fatigue techniques for two different microstructural conditions. Local texture surrounding micro-notches was found to influence micro-notch fatigue crack initiation in one of the microstructures. Fatigue crack initiation was least likely to occur from notches placed in neighborhoods with a microtexture unfavorably oriented for easy basal slip. However, small fatigue crack propagation rates were not influenced by the microtexture in these local neighborhoods. A systematic variation in micro-notch length indicated that fatigue cracks initiated from naturally occurring microstructural features when micro-notches with a surface length (2c) less than 15-20 um were machined in specimens.