First flight of A-12 the airplane that became the SR-71 was 1962. Shortening the time frame needed to acquire material. Machining of titanium is very time consuming as well.
> Machining of titanium is very time consuming as well.
And it was way worse back then given it was a field being actively developed.
Not to mention the development and characterisation of titanium grades and alloys, and their treatment (heat and solution).
According to the wiki, at some points Lockheed has to reject 80% of the titanium they got due to metallurgical contamination, and they had to rebuild tooling and processes because of corrosion issues with chlorine (from tap water) and cadmium (from tools plating).
And it was way worse back then given it was a field being actively developed.
Not to mention the development and characterisation of titanium grades and alloys, and their treatment (heat and solution).
According to the wiki, at some points Lockheed has to reject 80% of the titanium they got due to metallurgical contamination, and they had to rebuild tooling and processes because of corrosion issues with chlorine (from tap water) and cadmium (from tools plating).