Rr. Stephens et al., FATIGUE-CRACK GROWTH OF TI-62222 TITANIUM-ALLOY UNDER CONSTANT AMPLITUDE AND MINITWIST FLIGHT SPECTRA AT 25-DEGREES-C AND 175-DEGREES-C, International journal of fatigue, 19(4), 1997, pp. 301-308
Fatigue crack growth behavior was investigated for Ti-62222 titanium a
lloy under constant amplitude (R=0.1 and 0.5) and miniTWIST flight spe
ctra at 25 and 175 degrees C. Crack closure was observed at threshold
and near threshold for both temperatures with R = 0.1 but not for R =
0.5. Based upon applied or effective Delta K, fatigue crack growth beh
avior for a given R ratio showed no significant temperature effect. Mi
niTWIST flight spectra fatigue crack growth life at 175 degrees C, how
ever, was 2.5-3.5 times greater than at 25 degrees C. Fatigue crack gr
owth life calculations using NASA/FLAGRO were conservative. Fatigue cr
ack growth was transgranular with SEM fracture surface morphology depe
ndent upon both Delta K and temperature with significant increase in s
econdary cracking at 175 degrees C. (C) 1997 Elsevier Science Ltd. All
rights reserved.