The life evaluation by linear cumulative damage rule for cold dwell fatigue of Ti-6Al-4V alloy

Low cycle fatigue (LCF) life at ambient temperature of Ti alloys is well known to decrease with stress dwell. This phenomenon, called cold dwell fatigue (CDF), is influenced by the peak stress, dwell time, and microstructure. For this study, the CDF life was evaluated by the linear cumulative damage rule. The influence of test conditions and microstructure on the linear cumulative damage rule was also verified. By the linear cumulative damage rule, when creep damage is calculated using the time exhaustion rule, theCDF damage was evaluated by the inequality of D-Total = (D-F, D-C) <= (0.01, 10(-6)). However, the CDF damage can be evaluated in the range of D-Total = 0.6-1.2 when creep damage was calculated using the ductile exhaustion rule. Results indicate that the evaluation was almost independent of the dwell time, peak stress, and microstructure, so it is also a versatile method for evaluating CDF responses.

Automated summary

This study evaluated the cold dwell fatigue life using the linear cumulative damage rule, showing that the method is almost independent of dwell time, peak stress, and microstructure, making it a versatile approach for assessing cold dwell fatigue responses.