Environment effect on low cycle fatigue properties of some titanium alloys

Abstract

In this paper an attempt is made to investigate the effect of the environment on the low-cycle fatigue properties of four titanium alloys. The influence of an elevated temperature (200-650°C) and increased amount of hydrogen (0.004-0.08 wt %) in the alloy on the cyclic strength at constant-stress and constant-strain loading is analysed. Round (d=10 mm) and rectangular cross-section (4 mm×25 mm) smooth and notched specimens were tested. Fatigue crack initiation (length a#0.5 mm) and growth were observed by optical microscopy. The numbers of cycles to crack initiation and to final fracture were fixed. Analysis of the test data enabled the effects of both the temperature and hydrogen on the specimen lifetime to be determined.

3-D observations of short fatigue crack interaction with la2mellar and duplex microstructures in a two-phase titanium alloy

“…Finally, it should be noted that researchers have found significant environmental affects on both crack initiation and crack growth for some microstructures in Ti-6246 alloy [51][52][53][54]. While in the case of a colony microstructure crack propagation in vacuum and air was similar, in a duplex microstructure significantly faster crack propagation rates were observed in air compared to vacuum [52].…”