Effects of Cooling Rate and Stabilization Annealing on Fatigue Behavior of beta-Processed Ti-6Al-4V Alloys

Abstract

The effects of stabilization annealing and cooling rate on high cycle fatigue (HCF) and fatigue crack propagation (FCP) behaviors of beta-processed Ti64 alloys were examined. After beta-process heating above beta transus, two different cooling rates of air cooling (beta-annealing) and water quenching (beta-quenching) were utilized. Selected specimens were then underwent stabilization annealing. The tensile tests, HCF and FCP tests on conducted on the beta-processed Ti64 specimens with and without stabilization annealing. No notable microstructural and mechanical changes with stabilization annealing was observed for the beta-annealed Ti64 alloys. However, significant effect of stabilization annealing was found on the FCP behavior of beta-quenched Ti64 alloys, which appeared to be related to the built-up of residual stress after quenching. The mechanical behavior of beta-processed Ti64 alloys with and with stabilization annealing was discussed based on the micrographic examination, including crack growth path and crack nucleation site, and fractographic analysis.