Advanced Low-cost Titanium-alloy Materials for Aerospace Fastener Applications 2007-01-3839
A new, potentially lower-cost approach for the production of advanced titanium and titanium-alloy materials has been demonstrated using cryogenic technology. The alloys produced have an ultra-fine grained structure, high-angle boundaries, and finely-dispersed particulates having near-nanometer-scale size. These features combine to impart excellent strength levels, good ductility, and excellent microstructural thermal stability. In addition, the powders are macroscopically in the micrometer range having pre-alloying capabilities. This feature allows for easy handling, cleaner surfaces, and no environmental dangers.
This paper summarizes the preliminary results of the macrostructures, microstructures, chemistries, and mechanical properties achieved via the cryogenic processing. Initial results for commercially-pure titanium material will be presented, which show near-nanometer size nitride particles formed in-situ during processing and increased temperature stability of the alloy into the 925°F temperature range.
The Boeing Company and its raw material suppliers are actively engaged in collaborative efforts involving development and processing technologies associated with the production and fabrication of titanium and titanium-alloy powders, including cryogenic milling, to achieve long-term reductions in associated raw material costs. Near-term applications of this program are focused on aircraft fastener installations, where the goal is to replace certain conventional Ti-6Al-4V titanium-alloy fasteners. Further work remains to optimize the patented process through internal Boeing and government funded efforts and ready it for commercialization.