M. E. Martinez, J. Hebda, R. A. Graham, ATI Wah Chang, Albany, OR
It can be a challenge to compare data found in the literature on titanium alloy properties. The effect of processing history can make separating property differences due to a material composition from those due to processing a complex task. To assist in comparing the fatigue properties of Allegheny Technologies ATI 425™ alloy (4Al-2.5V-0.2Fe-0.2O) to Ti 6Al-4V Super ELI and Ti 3Al-2.5V alloys, a study was undertaken whereby the materials were processed similarly from billet to sheet. The temperatures for hot work and annealing were adjusted for each alloy’s beta transition temperature, but the reduction schedule and other process steps were identical for each alloy. Fatigue testing was performed on unnotched tensile coupons in the transverse direction with an R-ratio of 0.1. Stress versus cycles to failure (S-N) curves were developed for three anneal cycles for ATI 425™ alloy, as well as the Ti6-4 and Ti325 alloys.
Summary: Results from a comparative fatigue study will be presented. The alloys tested include ATI 425™ (4Al-2.5V-0.2Fe-0.2O), Ti 6Al-4V Super ELI and Ti 3Al-2.5V. Samples were tested axially with a maximum run-out of 10,000,000 cycles. ATI 425™ showed improved fatigue resistance over both Ti325 and Ti64 Super ELI.
