Soviet titanium submarine (Alpha-class)

Why the US chose not to build titanium submarines despite Soviet leapfrog. Hull cracking from creep-fatigue interaction. Faster than US destroyers; deeper than US depth charge collapse depth.

I said steel is heavy. To give you an idea: [Tom holds up a steel sample.] this is a piece of one-inch steel made about thirty years ago. [Tom holds up a second sample.] This is a piece of two-inch-thick titanium electroslag weld made at our Graduate Center when we were looking at trying to build a titanium submarine. Why have we not built a titanium submarine? A long time ago the Soviets did that. The main source of titanium — it's like aluminum, it's about the fifth most abundant element in the Earth's crust. Titanium is not scarce.