Soviet Alpha-class submarine

Used to make the point that titanium welding requires aerospace-grade cleanliness, not shipyard conditions. Tom's David Taylor conversations about whether a full-scale titanium submarine could be built in a US shipyard.

The other thing — if you just use regular old gas piping that we use for stainless steel and nickel and all these other alloys, you're going to get bad welds in titanium. You have to use metal piping for your gases. You could use some Teflon and some of these things are pretty good, but really you need to be as absolutely clean as you can. Your gas shielding for your welding process has to be brought in as if you were in a semiconductor manufacturing plant. That was one of the things back in the days of the Alpha sub, when we were talking down at David Taylor — you weren't going to build that in the shipyards you have today. No one's going to build a full-scale titanium submarine in that type of shipyard. They're going to have to build it in something that looks more like an aerospace facility in terms of cleanliness. You've seen pictures of Boeing — that doesn't look like the shipyard does, does it. If you're going to do a lot of titanium welding, that's what you're going to have to do. It's going to have to be a facility that you can sort of eat off the floor whether you want to or not.

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Background to Seawolf budget zeroing — congressional perception that Soviets had leapfrogged US submarine technology.

I had students who, when they became captain, were head of the program for the DDG 51, and then the Zumwalt class that just got cancelled. Millard Firebaugh was before my time. He was a 13A, which was before 2N, and he got a PhD here. He was in charge of designing the SSN 21, the Seawolf. I knew him when he was a captain designing the Seawolf. I knew him when Congress zeroed the budget for the Seawolf because the Soviets had developed a titanium submarine and Congress said, oh, they've leapfrogged us. I knew him when he went back up to the Hill to get the money back. I knew him when he became chief engineer of the Navy. And I was hired by him when they had completed 18% of the ship and had to tear it all apart in the early '90s, along with a few other people, to look over Electric Boat's shoulder and make sure they didn't make the same mistake the next time. He's still alive, retired obviously now.

By the mid-1980s the Alphas were being mothballed — they had cracking, were extremely noisy, and were expensive to maintain — which deflated U.S. interest in pursuing titanium submarines and set up the pivot to composites described in the workshop case.

One of my ideas originally was to put a little magnetic field around it to force that cathode spot to wander around on titanium. But that was about the time that all the Alpha subs were being mothballed — taken out of duty. They had cracks, they were noisy as could be, and they're expensive to maintain. The great interest in the early 80s subsided by the mid 80s for titanium subs.

Mentioned only obliquely via the US Navy's interest in non-ferromagnetic submarine hulls (titanium, then stainless steel) to evade SQUID detection.

I said they may be important for detecting magnetic fields, in what's called SQUID — superconducting quantum interference devices. The US Navy got very concerned in the late 80s that the Soviets would be able to put a SQUID in a satellite, and all of a sudden these big magnetic submarines would be magnetically visible in the whole ocean. They'd light up like a light bulb to a SQUID detector. At the time, you could fly an aircraft at 10,000 feet above the ocean with a SQUID detector and you could find the magnetic field signature of the steel submarines. The US Navy ever since has wanted to build a titanium submarine because it's non-ferromagnetic. They now want to build a stainless steel submarine because it's non-ferromagnetic. They want to get rid of this lousy ferromagnetic iron because superconductors can detect those submarines. The question is, could they do it from 100 miles in the air? With high-temperature superconductors it might have become possible. People were talking about magnetically levitated trains and all these wonderful things, and I said, you're not going to see magnetically levitated trains and big high-field magnets in our lifetimes or our grandchildren's lifetimes. There's the sound bite that someone will remember — we won't see it in our grandchildren's lifetimes.

Referenced as the titanium-hull submarine Gurevich's group taught the Soviets to weld. Tom notes a deferred discussion ("we may talk about some of this when we get to titanium welding").

When I went there in 1980 — we may talk about some of this when we get to titanium welding, I got to talk to their titanium welding expert, who was really the guy who taught them how to weld the Alpha submarine — they also gave me demonstrations. One of them was underwater welding. In the Soviet economic system the money didn't get divvied up on economic bases, it got divvied up on political bases. Someone with a fair amount of clout at the Paton Institute was really interested in underwater welding, and they showed me a wet weld. I saw the weld made, and they took it out of the water and it didn't look like some dog had just left this on the sidewalk. It actually looked like a regular weld, and it was a beautiful weld. We didn't have anything like that. Now, it's still going to be full of hydrogen, the weld chemistry is going to be different, but it was a beautiful weld.

1980 wake-up moment Tom recalls reading about in the International Herald Tribune flying back from Europe. Faster than US destroyers, deeper than US depth-charge collapse depth — but very noisy and full of cracks within years (Soviet Naval Research Lab had identified fracture problems they hadn't actually solved before building). Triggered US Navy titanium research funding competition (Jim Williams at Carnegie Mellon vs. Tom at MIT) and later the post-Alpha composite-submarine workshop in Reston.

A friend of mine — he wasn't always a friend of mine. When I first started as an assistant professor at MIT and he saw my name tag at a conference and saw MIT, he decided to battle me for the next five or ten years. We'd go to Navy titanium conferences. This guy was Mr. Titanium in the country. His name is Jim Williams, and when I started as an assistant professor here, he was starting as a professor at Carnegie Mellon University. We were both competing for Navy money in titanium. This was just before what the Soviets call their titanium submarine — the Alpha sub. I remember I was coming back from Europe and reading the International Herald Tribune when I read about the Alpha sub in 1980.

The Alfa sub becoming public knowledge ~1980; leapfrog of US submarine technology by ~2 years; creep-fatigue cracking failures; Congressional alarm and the David Taylor conferences. Tom's eventual inference that Gurevich used electroslag welding to build the heavy-section titanium hull.

The Navy still uses titanium, of course, in thin sections for tubing and piping. We heard about that, although you need to not mix it with some other things. But there has been an interest — although I think it's a decreasing interest — ever since the Alfa sub came out. The Soviets built the Alfa, and it became public knowledge that they had it in about 1980. They leapfrogged us in submarine technology for about two years, until these things started cracking due to creep-fatigue interaction.

The Alpha sub revelation on the *International Herald Tribune* front page in 1980 is the moment Tom realized why Gurevich had been publishing on electroslag — the Soviets had built a titanium-hulled submarine. Two years later the Alpha subs were mothballed: noisy, fatigue-cracked.

There are a number of welding processes that were used for welding titanium, one of which I didn't realize until 1980, in the Alpha sub. I was at a meeting down at David Taylor Ship Research Center in Annapolis, Maryland, and all of a sudden I realized Gurevich had been publishing in the early 70s on electroslag welding. Electroslag welding is a process where you have a wire feed, you have two vertical plates, you put a water-cooled copper dam on either side, and you put a little bit of flux in the center — you don't cover the whole length of the weld with flux, you put a handful of flux in there. You run the wire in, you melt the flux, and now it's the resistive heating of the flux that melts the wire and you just make a casting going up. [Tom passes around a sectioned titanium electroslag weld.] This is a two-inch thick titanium plate with a gap here. You can see where the water-cooled copper mold was, and the weld is this thing that's about two inches by two inches. Very efficient process.