Advanced Ti Alloys Applications for Affordability

The first step of the feasibility study is to identify the criteria and benefits against which to measure each alloy, and this is to be completed by the OEMs.  Possible criteria include but are not limited to: tensile properties (strength, ductility, modulus), fracture toughness properties, fatigue properties, crack growth rate, and lifing costs.
A lab scale ingot of the machinability alloy will be melted and converted to a small diameter billet product.  Simple shaped forgings will be thermomechanically processed at Ladish and property testing will be completed.  Ladish will complete tensile and fracture toughness testing along with optical metallography.  Additional microstructure evaluation will be completed by OSU and the OEMs.  The OEMs will also perform additional mechanical property.  The forgings will be machined using different machining techniques.  The machinability of this alloy will be compared to other traditional titanium alloys to determine the affordable feasibility of this alloy.  The machining comparison will be completed at Boeing, other OEMs, and IAMS in Cincinnati Ohio.

Two boron modified Ti64 alloys will be melted into a lab scale ingot and converted into a small diameter billet product.  The two compositions are a boron level of 1000 wppm and 1 wt.% B. The microstructure and the constitutive properties of the converted product will be analyzed.  Simple shaped forgings will be thermomechanically processed using various heat treatment schedules at Ladish and property testing will be completed.  Ladish will complete tensile and fracture toughness testing along with optical metallography.  OSU and the OEMs will complete additional microstructure evaluation.  The metallurgical evaluation will include analysis of failed test specimens from various types of tests to understand how the borides affect the failure process.  The OEMs will also perform additional mechanical property.  The mechanical and microstructure, including grain size refinement, property response and the amount of thermomechanical processing will be compared to traditional titanium and steel alloys to evaluate the affordability of the Ti64-B alloy.  There will be possibilities in subsequent tasks to expand the boron modification to other titanium alloys including Ti5553 if the Ti64-B alloys show feasibility.
PCT will also produce simple shaped thin and thick-sectioned castings respectively from each Ti64-B composition.  The castings will be evaluated for mechanical property and microstructure response.  Ladish, OSU, and the OEMs will complete detailed microstructure evaluation, including grain size investigations.  The OEMs will also perform additional mechanical property testing.  The mechanical properties and microstructure, including grain size refinement, will be compared to traditional titanium cast alloy applications to evaluate the affordability of the Ti64-B castings.

The Ti5553 alloy will be melted into a lab scale ingot and converted into a small diameter billet product by Timet.  The microstructure and the constitutive properties of the converted product will be analyzed.  Simple shaped forgings will be thermomechanically processed using various heat treatments at Ladish and property testing will be completed.  Howmet will produce simple shaped thin and thick-sectioned castings from the Ti5553 alloy.  Ladish and Howmet will complete tensile and fracture toughness testing along with optical metallography.  OSU and the OEMs will complete additional microstructure evaluation of the forgings and castings.  The OEMs will also perform additional mechanical property testing.  The mechanical properties and microstructure will be compared to traditional titanium and steel alloys to evaluate the affordability of the Ti5553 alloy.
Finally, all of the advanced alloys will be assessed against the application criteria and ranked in order of technical and economic performance by all of the team members.  Any alloys that meet all of the application criteria will be identified as technically and commercially feasible alloys and will continue into tasks 3-5 of this project.  Risks for each alloy and application set will be identified and will be critically assessed during the subsequent technology development task.