Watertown Arsenal titanium development

Local geographic anchor for Ti-6Al-4V development. Used to set up the BRAC closing story (50 million decontamination cost; DoD says "so what"; site becomes Watertown Mall) and Tom's later failure-analysis consulting role there.

If any of you have been to the Watertown Mall, which used to be the US Army's Watertown Arsenal, back in the days of the Civil War and even until about 15 years ago at the BRAC closing, the Army had a research reactor in this building. When they were in the first BRAC closing, they said, you can't close us, it will cost 50 million dollars to shut down the reactor and decontaminate the area. The DoD said, so what? They closed them, and now they've turned it into a mall. That's where Ti-6Al-4V was developed, at Watertown Arsenal, just after World War Two.

1945 development of Ti-6Al-4V — still the workhorse titanium alloy. The arsenal is now the Arsenal Mall.

So why are they making a hundred parts for Boeing? Tensile specimens. Boeing's going to do fatigue tests and tensile tests and impact tests, because Boeing has to certify to the Federal Aviation Administration before they put it on an airplane that it matches the properties that everybody else has measured for titanium 6 aluminum for the last eighty years. Where was titanium 6 aluminum developed? Anyone live in Watertown? Anyone been to the Watertown Arsenal Mall? The Arsenal Mall used to be the US Army's Watertown Arsenal when I was a student, and in 1945 that's where titanium 6 aluminum 4 vanadium was invented, developed. Titanium was a new material available after World War Two, and 6 aluminum 4 vanadium was the first commercial alloy. It's still the workhorse material for titanium alloys.

Watertown Mall today was the Army Research Center where titanium was first developed.

In any case, magnesium is 250,000 tons. Tin, which is not a structural material, is also 250,000 tons. I put it on there because it was on this list, this little graph that I'd stolen from someplace. Titanium — one of the wonder metals, first developed over here at Watertown Mall, actually it was the Army Research Center at the time. It's now a mall. If you go over there — Home Depot, TJ Maxx. Titanium is essential to the aerospace industry, but it's only 60,000 tons per year. I did learn that the B-1 [B-2] bomber uses about 100 tons of magnesium [titanium] to produce — that's not the weight of the aircraft. Only maybe 10% of that weight actually gets into the aircraft, but you have to produce about 100 tons to get the parts.

Brief historical anchor — Ti-6Al-4V was developed at Watertown Arsenal after WWII. Now the dominant high-strength titanium alloy.

Here's a buy-to-fly ratio of a real part. Titanium 6-4, this alloy we made over at Watertown Arsenal after World War Two, the most common high-strength titanium alloy in existence right now. Here's the final part — it's a hinge or something, a T-shaped part. In the old days you would make this out of a solid block of titanium, and you'd have a seventeen-to-one buy-to-fly ratio. 95.4% of your material goes as machining chips. Yes?

Brief historical anchor — titanium 6-4 alloy developed at Watertown Arsenal around 1945–47 as titanium first became available in larger quantities.

There's titanium six-four. I'll talk about the six-four alloy in a bit, but it was developed over here at Watertown Arsenal in about 1945 or '47, when titanium first started to become available in larger quantities. There's titanium 6211 — six aluminum, two niobium, one tantalum, and 0.8 moly. That is the U.S. Navy 100 ksi strength material. It has no other application that I know of other than the Navy buys it, because they did a lot of work at David Taylor to prove it out for strength, toughness, weldability, etc., back in the 1960s.

Passing reference. The 6-4 workhorse titanium alloy was developed at Watertown Arsenal — "which is now Home Depot." Used as a one-line historical placement of the alloy.

Well, here are different strengths, from just a plain old carbon 1015 steel — kind of like old automotive sheet, mild steel, whatever you want to call it — all the way up to A640, and even up to 300M, which is basically aircraft landing gear type steels, 300 KSI strength okay. It looks like steels can go to very high strength, but if you really talk about readily weldable steels, we're all down in here. Titanium, the workhorse alloy, six-aluminum four-vanadium [Ti-6Al-4V], developed over here at Watertown Arsenal — which is now Home Depot. It wasn't Home Depot at the time they developed 6-4. But it was Watertown Arsenal.

Watertown Arsenal (now Watertown Mall) developed Ti-6Al-4V around 1950, made possible by industrial-scale vacuum melting originating from MIT mechanical engineering.

They started working on refractory materials. Watertown Arsenal, which is now Watertown Mall, developed titanium alloys. The workhorse titanium alloy is Ti-6Al-4V — about 1950 they developed titanium alloys, all because of this technology to generate vacuum on an industrial scale, when you're melting metals that are giving off all kinds of gas. You had a big enough vacuum pump to suck this stuff off. Norton Research started right down here at the end of campus, and the building is between the Wang Center and the river. That was the Norton Research building. Now it's part of the Sloan School.

Student: That Norton —?

No, different Norton. There were two Norton brothers who were faculty members in this department, but it's not either one of them. I don't know which Norton that is, but it's a different Norton. My thesis adviser in the 1950s did his doctoral thesis on single-crystal tungsten, the deformation of single-crystal tungsten, because we all of a sudden had vacuums that we could grow single-crystal tungsten and niobium and all the refractory metals, and titanium light metals. Tantalum is one of those metals. So H.C. Starck over here in Newton — this is going back 70, 80 years — but one little development out of mechanical engineering at MIT has spawned off a number of different companies.

Tom's student welded armor-steel test coupons and quenched them in liquid nitrogen within five seconds to trap the hydrogen for analysis. The Morris Cohen anecdote ("the impracticality of great academics") follows.

No, not unless it's been reintroduced. It will cure itself if you keep it up. I know one case where it lasted a year, and that was in the High Sierras, where the weld was frozen all winter. If you want to keep hydrogen in steel: I had a student do his thesis 30 years ago on hydrogen cracking in armor steels. He was working for the Army over here at Watertown Arsenal. He would make his welds and within five seconds put them in liquid nitrogen, so he held the hydrogen in there long enough to do his hydrogen analysis. You all saw how fast it comes out. To get the actual hydrogen at the time of the weld, you can only extrapolate back, because you can't weld and do a diffusion analysis at the same time. Although Morris Cohen suggested that. That's where I learned about the impracticality of great academics.