A. P. Woodfield, C. E. Shamblen, GE Transportation, Cincinnati, OH

Summary:

Over the last 40 years, many papers have been presented on the influence of different microstructure parameters on Ti-64 mechanical properties. In spite of the extent of this research, it is often quite difficult to fully understand the role of microstructure parameters due to the fact that subtle chemistry and crystallographic texture differences can also play a significant role in influencing properties.

In the current study, the authors have attempted to eliminate the effects of chemistry and texture in order to understand the role of primary alpha grain size on mechanical properties of Ti-64. Material from a single heat of Ti-64 has been processed via different methods to form a range of primary alpha grain sizes, ranging from 3 microns to 15 microns. The crystallographic textures of these materials have been characterized, and based on this data, primary alpha grain size effects have been assessed on 6 and 12 micron primary alpha conditions.

The results indicate that 0.2% yield strength and high-cycle fatigue properties are significantly improved with reduced primary alpha grain size. Reduced primary alpha grain size did not significantly affect ductility, low-cycle fatigue and fatigue crack growth properties, while creep properties were modestly lower.