Why don't railroads need expansion joints?

The title of this video - which might change since I'm writing this up just a day after it was posted to YouTube - is a bit misleading. The actual question in the title - why don't railroads need expansion joints - is only answered in the last half minute or so of the video and is answered more thoroughly in a Practical Engineering video that I'll post after a jump.

The bulk of the video is spent explaining how railroad welds using thermite work. The video explains the nuances far better than other thermite videos I've posted before, explaining why the rails must be aligned and peaked, why the rails must be preheated (including a nice demonstration of heat treating), how the crystal structure changes as a result of the weld, and eventually why the rails don't need expansion joints.

This is the second of at least three thermite videos from Dr Derek. I thought I'd posted the first video to both blogs, but I can't seem to find it, so it'll likely show up next week.

Can I make Titanium Damascus?

tl;dr - Yes, he can, but it's expensive and involves a whole lot of oxidation.

Damascus steel has a noteworthy pattern that is really what Alec is trying to reproduce with the titanium shown in these videos. Here he starts with alternating grades of titanium stacked then forge welds them together.

The steps required to then anneal and machine the titanium billet that he produces are labor-intensive to say the least.

But he does get some cool rings out of the process.

Parts 2 and 3 of the series are after the jump.

In Space, No One Can Stop You From Welding

Cold welding is frickin' weird.

Richard Feynman wrote (or said in a lecture - I'm not sure which), "when the atoms in contact are all of the same kind, there is no way for the atoms to 'know' that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin layers of contaminants in between, the atoms 'know' when they are not on the same part."

But two metallic pieces that don't have those thin layers between them - primarily because they've been in space and rubbing against each other - can spontaneously weld together to become a single piece of metal.

It's possible to get that to happen on Earth, but it's not easy because of all the pesky oxygen we have around us all the time.

Metals are way weirder at the quantum level than we think they are, man.

Why Metals Spontaneously Fuse Together In Space

There is nothing cooler than space.

Nothing...

I'm willing to watch just about the most mundane bit of nothing if it's being done in space because nothing happens in space the same way that it happens here on the surface of Earth.

On Earth, two metals put next to each other stay fairly distinct from each other. (I don't want to hear about your dendritic growth causing shorts.)

In space, however, metals spontaneously weld to each other if the metals are in close enough contact because any sort of oxide layer - immediately formed here on Earth pretty much no matter how well we polish the two surfaces - simply doesn't form. As Dr Derek paraphrases from Richard Feynman's lecture, "when the atoms in contact are all of the same kind, there is no way for the atoms to 'know' that they are in different pieces of [metal]." 

Seriously, space is so totally foreign to our experiences.

HOW ROCKETS ARE MADE (Rocket Factory Tour - United Launch Alliance) - Smarter Every Day 231

So much to cover here.

The quick version is that Destin (of Smarter Every Day) shows us his tour of United Launch Alliance (ULA with their CEO, Tory Bruno. The ULA factory has some pretty highly-regulated manufacturing going on.

I'll go with a bullet point list of things I found interesting and possibly useful for a material science class. Admittedly, the full video - fifty-four minutes long - is probably more than any class could watch in total, but it's got some awesome clips.

• 5:15 - The video cuts to avoid filming "that" to Destin's left and right, items that Tory narrates but that he says flatly can't be filmed and shown.
• 7:15 - Quick discussion of the supply chain for the aluminum sheets that the rocket fuel tanks are made of
• 8:30 - We see the finished product of a machined isogrid panel as well as why that design - not the ideal design - was chosen because of the limitations of FEA analysis calculations in the 1990s.
• 9:50 - Discussion of the safety margins in space flight (1.1 - 1.25 times designed load) as compared to those of land-based transportation (7-12 times designed load)
• 12:15 - Amazingly, we get a mixture of, as Bruno says, "the pinnacle of technology...high-tech, robotic operations but mixed in [with] craftsmanship with people who are very skilled and have great attention to detail." That's amazing that something this precise is partially done by hand. This will come back in a bit.
• 13:30 - Machining, subtractive manufacturing is mentioned...as well as their recovery system for recapturing the aluminum chips for eventual recycling.
• 17:00 - 19:20 - Advertisement for Audible, skip it
• 19:30 - Replacing the isogrid with an orthogrid, saving time and weight, along with a quick discussion of strain and work hardening that happens by hand after the machining. We get a nice close-up of the orthogrid at 21:10.
• 22:00 - Destin uses the term strongback to describe the construction of the press used to curve the machined panels. That's a term I had to look up.
• 22:45 - Destin questions whether the aluminum is annealed, and Tory says they allow the aluminum to artificially age at room temperature after they are slightly work hardened from the curving process.
• 24:15 - Back to manual manufacturing to a precision level that - according to Tory - can't be achieved by automation. "You will always get better results by doing it by hand," he says.
• 27:30 - We see the anodizing facility to create a thick oxide layer for hardness and corrosion resistance. I knew that bare aluminum automatically formed an oxide layer, but I hadn't heard - as Tory says around 28:10 - that the natural layer is very thing and porous, leading to poor corrosion resistance.
• 31:30 - I wonder what the various acid concentrations are.
• 32:10 - We head toward the friction stir welding area, and Tory explains why friction stir welding is the better choice for strength of their final tank.
• 34:05 - Destin 'peaks over there' at a highly pixelated area. Cute
• 36:00 - Quick explanation of why it's better to order one large pizza than to order two medium pizzas
• 37:40 - Another pixelated section with the specialized head of the friction stir welder
• 40:15 - We switch over to stainless steel - half the thickness of a dime - instead of aluminum as we switch from boosters to upper stages. 
• 43:00 - We get a finished view of the 5m composite payload faring and a discussion of ULA having brought the manufacturing of that from Switzerland to north Alabama via business partnership.
• 44:00 - Bruno discusses ULA's record of flying both payload and actual people successfully with 135+ consecutive, successful launches. 
• 45:20 - Discussion of mass fraction (without explanation)...I had to look that up, too.
• 46:30 - Changes coming from hand arc welding to automated welding in the next version of Centaur (the upper stage) to save time (and assumedly cost).
• 47:40 - We get a quick glance of the team of people who are walking around behind the scenes with Destin and Tory. Admittedly, it looks like Tory is taking Destin around solo, but there are clearly people supervising even the CEO the whole time.

In general, I'm incredibly impressed with Bruno's knowledge of the entire process. It's amazing to see that from a CEO. Maybe that's the way that all CEOs are, but I doubt it.

And, if you want even more, there's a second video - on Destin's second channel - where the guys get into some discussion about the rocket engines themselves and ULA's position within the industry. It's less materials-focused, but it's worth watching.

Railroad Thermite Welding: Europe & Russia

(Edit: As of 6/28/21, the old video had disappeared from YouTube, and I wasn't able to find it anywhere. I was able to find the animation, however, and since that's the only really important thing, I'm reposting that video. If you want to find videos of railroad welding, I have others of that, too.)

Yup, dramatic music at the beginning. That's...um...awesome?

In addition to possibly watching this with the sound off, I'd also suggest turning off the annotations because they're just annoying ads for other videos.

There's a pretty stunning, handheld blowtorch at 0:30. All those tiny flames makes me wonder just how frickin' hot the torch gets.

Most of what we get in the video - including the phenomenally bright fire at 1:55 - is pretty standard railroad, thermite welding.

The animation at 2:09, however, isn't standard. It's a great cutout view of what's happening within the thermite weld.

After that, there isn't much more than three barely  different versions of thermite welding. The first ends around 3:05. The second ends around 5:50, and the third wraps up at about 8:25.

Really, the animation at 2:09 is the only new thing to see here.

Clean Cut Metal Works

That's certainly one way to make a rainbow permanent.

This series of photographs of gorgeous welds (rainbows caused by layers of oxidation) was attributed to the same metal artist who makes sculptures are Clean Cut Metal Works.

I'm skeptical because none of the work on CCMW looks anything like the photos above (gorgeous thought they may be in their own rights. Admittedly, I have zero experience trying to weld anything together (though I've done some very basic soldering).

If anything, those above look more like the ones on TheFabricator website.

The power of the mini arc furnace

There is a level of do-it-yourself project that is within my grasp.

Tighten up the hardware on the kitchen cabinets? Sure

Cut down the bushes out front? Got it

Even making the King of Random's mini metal foundry? Probably

But I'm the first to admit that I very quickly reach projects that are our of my depths, like making and then using the King of Random's mini arc furnace.

This one scares the mess out of me, and I'm going to strongly recommend that you only step into these depths if you know what you're doing.

But if you do know what you're doing, the one looks pretty awesome, using a homemade arc reactor to power an arc furnace, producing molten aluminum or copper for casting.

Be careful out there, folks...

Metal Fabricating in a New Millenium

'The Bean' - officially Cloud Gate - in Chicago is a brilliant piece of sculpture. 

If you haven't had a chance to visit and walk under Cloud Gate, you have to make sure you do so when next you're in the Windy City. There are few enough opportunities to share a public experience like Cloud Gate with a hundred of your closest friends, and seeing Cloud Gate is one of the best examples of that experience.

But how the heck was it made? It can't have been cast that large, right? And if it's sheets shaped and welded, we'd see the seams, right?

Check out all the details of the production of Cloud Gate in a great article about Cloud Gate over at TheFabricator.com. It turns out it's a fascinating process involving way more hand-skilled work than I would ever have guessed. (In case the article disappears, I've uploaded it to Scribd.)

A less-detailed article about The Bean can be found on Outo Kumpu's website (They made the steel for the sculpture.) Again, I've uploaded this article, too.

Mjölnir (Thor: The Dark World) - MAN AT ARMS

There aren't any new material being used in this video, but there is a guy making the Hammer of THOR!

Or rather a nice recreation of the hammer of the gods.

At about 5:45, though, there is a vulgar word on the shirt of the narrator/creator. Be careful if you're planning on showing this in class, folks.