Considerations in fatigue lifing of stress concentrations in textured titanium 6-4

The effect of crystallographic texture has been considered in attempting to derive a total life prediction capability for the titanium alloy Ti6-4. Orientation effects due to texture are shown to be a result of stress relaxation in strain control specimens, and consequently occur in some cases of notched specimens. It is shown that these effects can be predicted using analytical methods such as the Modified Coffin–Manson and Walker strain approaches. Additional failure mechanisms such as cold dwell prohibit accurate predictions at higher R ratios. It is also acknowledged that texture effects can occur in the crack propagation phase of notched specimens and should be considered in a total life model.