| Abstract Scope |
Titanium alloys are susceptible to LCF loading, partly due to the their low strain hardening; most alpha/beta titanium alloys have a relatively “flat” response in their stress/strain curve. This is typified in Ti-6Al-4V. Indeed, this results in LCF strengths much below yield, in contrast with other systems, such as austenitic steels. In this work, a novel alpha/beta titanium alloy was developed, which has an LCF strength exceeding 1000 MPa, superior to Ti-64 and Ti-6246. An increase in the initial hardening rate, compared with Ti-64 and Ti-6246, was observed in this new alloy. This might offer a sort of protection; i.e. the grains that plastically deform first are able to harden, eventually shedding load onto other grains, resulting in an increase in flow stress. The nature of increased hardening was explored through micro-mechanical testing, probing the CRSS and strain-rate sensitivity of individual slip systems, combined with dislocation analysis in the TEM. |