Heat treatment to reduce embrittlement of titanium alloys
AssigneeUnited Technologies Corporation
InventorsJames O. Hansen, David Novotnak
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Abstract
A non-burning Ti-V-Cr alloy which is heat treated to decrease its susceptibility to embrittlement in gas turbine engine compressor applications. The invention heat treat cycle consists of an isothermal holding period below the alpha solvus temperature, a slow ramp down to a lower temperature, a second holding period at a lower temperature, a third ramp down to an even lower temperature, and a final holding period at the third temperature. Other suitable heat treat cycles within the concept of the invention include a single holding period below the alpha solvus temperature double holding periods below the alpha solvus temperature with a ramp from a higher to a lower temperature and a continuous ramp below the alpha solvus temperature with no holding period.
Claims5
A method to improve the high temperature stability and embrittlement resistance of a true beta titanium alloy based on titanium and containing a nominal composition of 35% vanadium and about 15% chromium and having an alpha solvus temperature, the improvement comprising
- a. heating the alloy above the alpha solvus temperature for a period of time sufficient to solutionize any alpha phase present, to produce a fully beta phase microstructure;
- b. heating the alloy at a temperature about 150.degree. C. below the alpha solvus temperature and holding for a period of time;
- c. cooling at a controlled rate, whereby a small quantity of the alpha phase is caused to precipitate and large precipitates rather than a continuous grain boundary film.
Dependencies are inferred from the claim text.