U.S. Navy heavy-section titanium submarine welding

Titanium, 75 times. In the old days I was involved in some of the early titanium submarine stuff. My first research contract was on welding of heavy-section titanium for the Navy. Austenitic nickel-based alloys, things like Inconels — your nuclear reactor materials — 100 times the cost. So we've got two orders of magnitude difference in cost of metals.

Tom's first Navy research contract as a young assistant professor was submerged arc welding of 6Al-4V for heavy-section submarine hull development. Funded by Office of Naval Research. Contact at Navy was a graduate of the department. Program also covered creep-fatigue interaction studies at NRL.

This was in the 1970s. The first research project I ever had as a young assistant professor was to do submerged arc welding of titanium. Here are some of those welds we made on six aluminum four vanadium. Why were we making these welds on titanium? This was the 1970s, and titanium would make the best submarine — much better than any of the steels, much better than aluminum. The U.S. Navy was working on heavy section titanium in the 1970s, which is when I started as a young faculty member. I knew from my old house tutor that the Navy was interested in titanium, and they had some research money, and the guy at the Navy was a graduate of this department and was giving out the money. That's how I got my first contract to weld heavy section titanium, which is why we made the first electroslag welds about 1980.

Ti-100 is the Navy alloy for titanium submersibles; same ratio-analysis story as steel, with one-inch critical flaw size at the strength of interest. "They've never had the money to build" — program never executed.

Titanium. The Navy was interested in titanium for submarines, so they did the same thing. Now we're up at about sixty percent of the strength of steel in terms of both toughness and strength, and you still have the one-inch critical flaw size. Ti-100 is the Navy alloy for titanium submersibles, which they've never had the money to build. You have this same analysis in terms of critical flaw size if you want to go to 180 ksi strength. Titanium sheets, if you go back, have a much higher toughness. The thin titanium sheets we put on fancy aircraft now have a much higher toughness than the plane strain fracture toughness. All these ratio-analysis diagrams are for the plane strain fracture toughness — thick stuff for building submarines, basically.

Mare Island Naval Shipyard attempted to use GMAW (gas metal arc welding) technology developed at David Taylor / Annapolis to build the Sea Cliff titanium hull. Failed after six months; fell back to GTAW (gas tungsten arc), which took a year to deposit the 2¼" weld at ~4 inches/minute. Used to teach: naval shipyards' lost capability to *build* (vs. repair) vessels, and the cost-of-time tradeoff in titanium welding.

When the Navy built the Sea Cliff, they did it at Mare Island. Partly they wanted to give — that was when the Navy was still in the idea of naval shipyards building things, rather than just repairing them. They wanted to get the experience, and they tried to prove out the welding technology that had been developed at David Taylor in Annapolis, gas metal arc welding, and they couldn't do it. They tried for six months and it just didn't work. They finally used gas tungsten arc. Took a year to build that hull, because gas tungsten arc puts down a little bitty bead about the size of a wire, and just kind of building up a two-and-a-quarter-inch-thick weld takes a while when you're laying things down like that at four inches a minute, of a guy sitting there like this. But they built it, if you want to spend the money.

The Navy spent millions on gas metal arc welding of titanium that the Soviets had already determined didn't work. After Tom's electroslag and semi-submerged GTA findings, the Navy classified the research. The Sea Cliff submersible (§6.p4) was the Navy's own attempt — they ultimately gave up on GMAW and went back to slow GTA.

So in the mid-1980s you will see coming out of Ohio State all these projects on trying to do Marangoni flow for gas tungsten arc. They wanted to make it work for steel. Doesn't work so well for steel; works great for titanium. The Soviets were doing it in the 60s. I was the only person outside of the US Navy welding heavy-section titanium — that's another story. In 1980 when the Alpha sub came out, and then I tried the electroslag, kind of a light went on at this meeting. I thought, that's why Gurevich was doing this — like I had been trying to do submerged arc — and then I started thinking of his semi-submerged arc. So I came back and I did electroslag welding, semi-submerged arc with this little flux for gas tungsten arc, and then the Navy classified everything, so I quit doing any of that work. You can't do classified work on campus. I didn't want to even touch it. I basically sort of quit doing most of my titanium work at that point.

The classified context for Tom's electroslag titanium work — once it became clear the technology was militarily useful, Tom's project was classified and he could no longer work on it. Forms the policy frame around the technical content.

Electric Boat has a whole facility down at Quonset Point to get the extreme circularity you need for a good pressure hull in steel. They have an indoor building that cost $200 million down at Quonset Point so they can weld these things. They weren't using electroslag, they were using gas metal arc on the steel. But you could do that with electroslag, and the Soviets, the Paton Institute, were the leader in electroslag technology in the whole world. Gurevich had quit publishing on any of the titanium work, and so on my titanium project, when I came back, we took some of our one-inch plate and we made the first electroslag weld outside of one research project in France and the Soviet Union — at least the first one I know of. We made it just in the room next door. It was a terrible weld, no fusion, but we found that titanium is easier to electroslag weld than steel.

Tom's first research project, 1977: Navy contract to weld 1-inch-thick titanium for submarines. Shown as physical artifact in lecture. US never built a titanium submarine other than *Alvin*.

So they had a huge welding institute and they developed technologies like — if you've ever read The Hunt for Red October or seen the movie, they had titanium submarines. My first research project, in 1977, was from the US Navy to weld titanium for submarines. [Tom holds up a 1977-era titanium weld sample.] This probably belongs in the Smithsonian. We were welding 1-inch-thick titanium for submarines. The United States wanted to build titanium submarines. We never built one, other than the deep-sea research vessel Alvin that went down and found the Titanic. The Navy built that as part of a prototype program to learn to weld titanium for bigger ships, because titanium submarines have the same strength-to-weight ratio advantage that aircraft and fast-moving vehicles need. You want high strength-to-weight so you can dive deeper and, hopefully, if you lose power, pop to the surface rather than sink to the bottom — because if you sink to the bottom, everything gets crushed, including the people inside.