Watertown Arsenal titanium hinge part (post-WWII)

Tom locates the invention of Ti-6Al-4V at the Watertown Arsenal in the 1940s while introducing the workhorse superplastic titanium alloy. Includes the BRAC closure aside and the Civil War cannonball history. Used as biographical color for the alloy, not a developed case.

Here are some compositions of superplastic alpha-beta titanium alloys. 6-4 titanium is the workhorse titanium alloy, invented over here at Watertown Mall. Actually it was Watertown Arsenal until about 20 years ago, when it died in the first round of BRAC. It was built before the Civil War to make weapons for the Army. They made cannonballs there during the Civil War. In the 1940s they invented titanium-6-aluminum-4-vanadium, which is superplastic in the 900° Centigrade range. There are a number of different titanium alloys, but they're all in this 800 to 1000° Centigrade range, with elongations at strain rates of 10⁻⁴ per second in the 300 to 1000% range.