HY-80 and HY-100 steel development

Cost of qualifying new pressure vessel steels — $50M in 1960s money for HY80/HY100 development; today hundreds of millions. Referenced as benchmark for DoE's stalled 9% nickel / Ni-1Mo qualification effort.

When I said it cost fifty million dollars in 1960s money to develop HY80 and HY100, they were doing full trials. But you can have a whole 200-ton heat made by US Steel for probably half a million dollars back then. Today, if you want to develop a new steel, you're probably in several hundreds of millions of dollars in different qualification tests.

So I said, you've transformed to martensite, because martensite is the material that's most susceptible to hydrogen cracking. What do we make our HY steels out of? Martensite — because it gives us high strength. What did we do when we went to HSLA steels? We got rid of the martensite. We now have very fine grain controlled-cooling steels that give us high strength, fine grain size, without a lot of alloy content. So what are we doing with HSLA steels? We were smarter in the 1980s to lower the alloy content, get rid of the martensite, and end up with a more weldable steel. And all we had to do was copy what the Japanese had been doing for ten years. Okay.

Passed around as $2–3/lb benchmark to contrast with $12,000/lb X-33 composite. Manufactured at Electric Boat, Groton.

[Tom hands a piece of HY-80 around.] This is a piece of HY-80, made by our friends down there in Groton. You'll feel the weight and density. As-fabricated, that's probably two or three bucks a pound for the cost of what you're going to float or sink, as the case may be. [Tom hands a piece of X-33 composite around.] That is a piece of the X-33 space plane that cost $12,000 a pound for that composite. So you've got $2 a pound and you've got $12,000 a pound. But it's light, isn't it? It's not as strong and it's more brittle. It wouldn't do well in an explosion. But you can get things into space and still have some payload left over. You can afford it at $12,000 a pound. You could make an Indianapolis racer out of that material, but you can't afford to make a Ford Taurus out of it and sell it to anybody.

If I were welding steel, this happens to be an example of welding two plates of different thickness, and they show how you would taper one down in aluminum. Because steel has more toughness, which means it can tolerate sharp corners a lot more than aluminum. It has lots of ductility. Aluminum doesn't have as much ductility. The director of research at U.S. Steel — admittedly not the most unbiased person when it comes to aluminum — this is John Groves who helped develop HY-80s back in the 50s and 60s, when I was a young engineer I heard him say he called aluminum "the near-metal." Steel was the metal and aluminum was nearly a metal. Might have a little ductility but it wasn't anything close to steel, according to John. There's some truth to that, but it's also a little bit unfair.

HY-80 was developed at U.S. Steel under Navy program, jumping submarine hull yield from ~50 ksi (WWII) to 80 ksi, with corresponding depth-capability gain. Paired with Rickover's nuclear reactor development. Brief mention, framing the postwar payoff of Pellini's brittle-fracture work.

Sometimes they get brittle fractures, sometimes they get a bulge before the thing fractures all the way, sometimes they get great big nice ductile things before it finally starts to tear. They can correlate that to other things. Pellini did all kinds of work on figuring out how to weld ship steels. Along with that came, in the mid-50s, the building of the Nautilus nuclear submarine out of HY-80, which was also a program started at U.S. Steel by the Navy to develop a higher strength steel. The submarines in World War II were probably 50 ksi steel. HY-80 was 80 ksi yield. So you had a big improvement in depth capability. And then Rickover developed the nuclear reactor so they could stay under, go underneath the pole and everything.

Used as the canonical example of an alloyed-for-hardenability steel: 1 inch thick, low carbon, ~3% alloy (Ni, Cr, Mo) for through-thickness hardenability in submarine hull plate.

If I put all this together: hardness is a function of carbon; hardenability is a function of the alloy content, and it's the depth of hardening. If I'm making automobiles out of sheet metal, I can use carbon steels because the sheet metal's no more than an inch thick. If I'm making some big pressure vessel, I'm going to need to use some alloy content. If I'm going to have a hard naval steel — if I'm building a nuclear submarine, here's a nuclear submarine steel, HY-80, inch thick, it's got to have a low carbon content, it's got about 3% alloy content in it. It's got nickel, chrome, molybdenum in this steel for hardenability. Because it turns out if I take that iron-carbon phase diagram and I quench it — I take it up here to the austenite and I quench it down here to the ferrite very quickly — I won't form a body-centered cubic crystal structure, I'll form a body-centered tetragonal crystal structure, which is known as martensite. Martensite is extremely hard. It's an athermal transformation, which means it occurs at near the speed of sound.

HY-100 noted as same composition as HY-80, different heat treatment.

If you look at some of these other things — they once wanted to use an alloy which is very similar, actually it's the predator [predecessor] alloy, to what is now HSLA-80. There's HY-80 that was developed in the 1940s and 50s by U.S. Steel, used in the Nautilus submarine, and used until recently — recently being twenty years — on other subs. They built a couple of HY-100, which is actually the same composition, just a different heat treatment, to give you HY-100. The Navy in the 1960s developed HY-130, and we've never really used it for a full-size ship. We can talk about why.

HY steels framed as the achievement of the 1950s–60s Navy-funded weldability research. Tom holds up his own 30-year-old HY80 weld at §7.p1 to show the heat-affected zone. At §10.p2 he discusses a 100 ksi quenched-and-tempered plate (HY100-class chemistry but lower) that failed Charpy.

Why do people think they can solve all welding problems with metallurgy? Because historically, education of welders in this country started big-time at Lehigh University in the 1940s. Bob Stout was dean of the graduate school — Stout and Doty wrote Weldability of Steels in the 1940s. That was a big place doing welding research. Some of those guys went out of Lehigh to US Steel and they developed all the HY steels in the 50s and 60s with Navy money — those high-strength submarine steels — and they had to be weldable because they were going to make submarines out of it. But Lehigh didn't keep their faculty current in that area. They had Al Pense, who's still around, but he rose to become provost of the university. Once you get to the administrative levels, you stop minding the store at the lower levels.