How Japanese Masters Turn Sand Into Swords

This isn't a replacement for the Nova episode "Secrets of the Samurai Sword". 

...but the Nova episode tends to appear and disappear from YouTube and DailyMotion with fair frequency, so you might need another video that goes through the ancient art of creating samurai swords from the initial collecting and smelting of iron-rich sand through to the slicing of tatami mats to demonstrate the sword's quality and the sword wielder's technique.

This video's contents...

• 2:00 - why bronze was used for sword and was eventually replaced
• 3:00 - cyanobacteria creating oxygen that precipitated iron from ancient oceans
• 6:30 - carbon + iron = steel, initial interstitial positions shown...why alloys are harder than pure metals
• 10:30 - slag formation and removal from the 'ancient' forge
• 13:30 - forging the steel by master swordsmiths
• 14:30 - folding the steel - how and why
• 16:15 - how carbon atoms migrate to different positions and form ferrite, cementite, perlite, and martensite
• 18:30 - differential cooling rates via clay thickness creating different steel types and the distinct blade shape

Another great video from Veritasium and one that shows that he's got a team of folks making videos with/for him at this point...and it's short enough at about half an hour - to get through in a single class period, unlike the Nova episode.

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.

process of making Damascus knife. Korea's top handmade knife master.

There simply are no words.

I mean throughout this twenty minute video there literally are no words spoken.

Instead, we just watch a knifemaker craft a single, beautiful knife from initially forge welding stacks of steel together to testing the finished knife.

It's mesmerizing.

Self organising steel balls explain metal heat treatment

TL;DW - Top video great, absolutely show in class...second video mathematical diversion, not efficient use of class time, good math...third video between the two - more mathy but more tightly edited and efficient and material-science-course tied)

I'm posting all three of these videos together because they're part of a series that Steve Mould made (with help on the lower two) exploring ball bearings and ball-pit balls as crystalline modeling tools.

In the above one, Mould makes a really fancy version of our ASM BB board (we use CD cases and airsoft pellets - he uses plexiglass and metal bb's, more akin to the Atomix toy of yesteryear). If you want to make something like his fancy version, here are a couple of links to check out.

Mould uses the BB board the same way we use it in class: to discuss grains, grain boundaries, heat treating etc in crystalline metals. He places the BB board on a shaker to model adding energy via heat (and there's a brilliant view of vacancy defects moving through the crystal at 2:27 and again at 2:35). Mould then discusses how the crystalline structure he's modeling affects the macroscopic properties (hardness, toughness, strength, etc) of the metal.

Honestly, it's a great explanation of about half a day of summer camp, even admitting that his model is limited in exactly how accurate it is compared to more complicated reality. He mentions a couple of videos that go further. I've already posted one and will look at the other.



The second video is Mould and Matt Parker going through to find the most efficient packing for spheres - using ball pit balls. They then shift from tetrahedral packing to a more square packing - which turns out to be exactly the same (check the below video to see that they're the same). 

I'll warn you that the second video is a lot less professionally laid out and more heavily math-leaning. (There's a slightly more organized video that shows about the same content.) But Mould and Parker do cut a whole bunch of oranges trying to calculate the percentage of space occupied in the face centered cubic packing. (It an IRL version of a computer animation that we use in class and that I'm STUNNED to see I haven't posted on the blog before - coming in two weeks now.) We include a mathematical version of the proof at 16:55 in our summer camp powerpoint (at least Becky and I do - check slides 85 & 86) and you can find the math laid out here, too.

The last video is back to Steve Mould's channel and shows - using ball pit balls and a cardboard box - hexagonal (and face centered cubic) packing. They use that to demonstrate stacking faults (maybe defects, maybe disolcations, maybe grain boundaries - I need to figure out which term is most correct there), brilliantly shown with the color-coded balls from about 6:00-8:00.

The idea that the face centered cubic lattice is really and A-B-C (repeat) hexagonal arrangement whereas hexagonal close packing is A-B (repeat) is kind of mind blowing and so brilliantly well shown with the ball arrangement. The ABC diagram is a little weird to me and very much a mathematical diagram, something I wouldn't get into in class.

Tempering Process

I've had a few former students sell Cutco Knives. I did end up buying a couple of knives from the first student because I had pitty on his 'cutting the rope' demonstration. In the long run, I haven't been impressed with the knives.

That all being said, I do use this video in my class to show quenching and tempering. It's a great show of those techniques.

Annealing Metal

Yeah, but how do you get the bracelet to be the right shape and size?

Do you actually wrap the cooled, annealed metal around your wrist, or is there some sort of mandrill that you use as an arm stand-in?

And how do you get the pretty, peened appearance on the surface of the bracelet?

I have so many questions - because I pretty much understand that annealing the metal makes it more workable (while admittedly, developing some pretty nasty scale).

MAKING A BOWIE KNIFE WITH REAL ENGINEERING!!! PART 2 - WHY we heat treat steel!

Finally, the testing...

The first part of the video is more making a knife - grinding the blade, drilling to attach the handle.

Then, at 5:50, the actual materials testing comes in. Alec Steele takes a steel bar and heat treats it different ways (not on camera, sadly) and gives each piece a few solid wacks with a sledge hammer.

These two videos (Alec's and Real Engineering - whatever that guy's name is) really balance the two sides of material science. Alec shows a lot of a practical knowledge. Real Engineering shows a lot of academic knowledge. Together they're pretty awesome.

Oh, and the testing wraps up around 12:25. Then it's back to finishing off the handle of the Bowie knife.

Heat Treatment -The Science of Forging (feat. Alec Steele)

There is something weird happening with the Real Engineering guy's accent. I'm struggling to place it exactly. There's a sing-song lilt to it that's screaming, "Irish" to me. Then, at 1:50, there's a weird ll-th thing going on with the 'through the heat treatment process' phrase that makes me think he's almost got Welsh in there. His patreon page says Galway, Ireland, but I've not heard that ll-th thing anywhere but from Wales.

Can anybody definitely say where he's from?

I'm going to have to check out the testing video from Alec Steele (an aptronym). Maybe that'll be next week's post.

So much great metallurgical explanation here...BCC, FCC, ferrite vs austenite vs pearlite, phase diagrams, quenching vs tempering vs annealing (normalising - British spelling, natch).

Quenching Steel: Understanding The Why's and Wherefore's

(Edit: 6/28/21 I can't find another upload of this video. The channel that hosted it is still there, but this video seems to have disappeared. I'll check again and hope that Trent brings the video back.)

Trent's back!

Honestly he never left, but I didn't look any further into his videos than his "Moronic Jet Fuel 9/11 argument" video.

Turns out he has more to tell us...

This video goes through differences of oil versus water quenching...what quenching does to the steel of the blade (with an interesting to a latex glove as an analogy to the quenched steel)...and comes to the final lesson, "if you do not know what steel you are dealing with, you will not know how to properly quench it or harden it or temper it"...

He does, I warn you, use the word 'retard' again at about 0:28 - the "new samurai retard squad". C'mon, Trent, spread the word to end the word.

What quenching and tempering does to SWORDS

Trigger warning: Aussie accent...keep hacky comedians and actors away lest they start doing the Philosophers song.

There's a whole bunch of high-quality explanation in this one...

• 1:19 - percentage breakdown of carbon in various steels (low carbon, medium carbon, high carbon)
• 1:49 - "When the iron is hot...reaches the austenite phase...lost magnetic interaction...body centered cubic or face centered..." Honestly, he screws up the crystals verbally (though the graphics are correct) but does nicely say that "there's more room in between the iron atoms when it's this hot which means carbon atoms can all fit around evenly wherever they want" and that "when iron is cool...they try and squeeze out the carbon in between these iron atoms" and shows ferrite in the graphic
• 2:56 - micrograph of ferrite and cementite as the carbon in squeezed out from between the iron atoms, making pearlite
• 4:16 - Say "crystals" not "structure", man...c'mon
• 4:44 - discussion of work hardening and how that's lost once the metal is reheated, "it loosens the insides. It basically gives the opportunity for the stresses to be released and moved around and become uniform...as soon as you heat it up, you're losing whatever benefits - but also detriments - you might've put into the steel"
• 8:16 - "When heated up to where austenite is formed in the steel, the carbon is not forced into these veins/pocket/lines...and if you were to cool it down rapidly, you can actually give those iron atoms not enough time to force [carbon] out into these more condensed pockets...and a different, amazing crystalline structure is formed within the steel called martensite"
• 9:40 - "[Martensite] can be very useful to swords because you want swords to have a very hard edge, but you don't want them to be too brittle"...Goldilocks of metals, eh
• 10:05 - how the Japanese solved the problem, great diagram of the anatomy of a samurai sword (ion core, pearlite jacket, martensite edge) created via clay control of cooling rate
• 11:50 - tempering makes its appearance...we've been waiting, Shad
• 12:30 - showing quench of a katana with differential cooling causing bending in both directions (flubbed vocals but corrected captions)
• 13:10 - "[tempering] releases stress between these dislocations creating a much greater level of ductility and flex in between the crystal structure that's being formed within it" - nice micrographs of martensite and tempered martensite
• 15:00 onward...what makes for a good sword, particularly its sharpness...not so much material science 

Shear Pins are Smart (They're Mechanical Fuses)

I'm not a car guy.

I'm even less of a tractor guy.

I pay to get my oil changed, and I'm happy to do it.

So, when it came up in our summer camp discussions that quenched metal would be useful for shear pins, I wasn't really comfortable with doing more than just nodding and smiling. "Yeah, shear pins...exactly."

Then I had to go look up what shear pins are.

Now, here's my understanding. Shear pins are hardened steel, typically quenched steel. Sometimes a rotational part of the machine - the lawnmower blade, the snow-blower - gets blocked and stopped. There's a driveshaft feeding rotational energy to that blade, however. Something in the chain  then has to break because the motor is continuing to try adding more rotational energy to the now-stuck blade.

If all the parts were equally tough, the break would take place randomly.

Instead, the engineers intentionally put in a weak spot, a quenched piece of metal called a shear pin. The intent is for that piece to be where the break happens because it's the cheapest part of the chain. It's better to break the cheap part than to maybe break one of the expensive parts.

Man, it's almost like people are smart.

I'm happy to say that I'm getting smarter every day.

Raw Craft with Anthony Bourdain - Episode Four: Bob Kramer

Well, yeah, who doesn't turn a meteorite into a chef's knife in their spare time?

Bourdain visits with Bob Kramer, a master chef's knife maker who goes through the smelting, forging, and heat treating of some pretty spectacular knives.

At about 5:38 (explanation starts) then at 6:18 (actual visual) is one of the - if correctly described - most stunning things I've ever seen in material science. Kramer explains that there is a 'shadow' that moves through the steel as it - as I understand - undergoes the phase change from FCC to BCC, squeezing the carbon into the harder, BCC form of iron.

I am currently looking for confirmation from a second source, however, that what we see is actually what Kramer says it's showing.

ALCOA - Production Video

Aluminum is a miracle. Its reactivity is so high that our ability to purify it from its ore just stuns me, seriously stuns me every time that I think about it.

I warn you that this video is narrated by a British voice, so it does refer to aluminum as aluminium. Just thought you should know...

The video follows aluminum through the processing to take the ore into a somewhat finished form...

• refining of bauxite ore (grinding, mixing with caustic soda - NaOH, and heating) into alumina
• smelting the alumina in a bath of molten cryolite
• passing electrical current through the mixture
• processing of the ingots (at an ALCOA factory, of course) into plates
• casting
• homogenizing
• scalping (sawing & milling)
• heating & rolling 
• shearing & cropping
• horizontal solution treating (5:15 - which seems to use water, not a solution)
• stretching 
• precipitating/aging
• conductivity testing & ultrasonic inspection (both non-destructive testing methods)

Sep 11 - "Why the Towers Fell" - Nova PBS

It is human nature to look back with one eye to the future. If we can just figure out why that happened, we can make sure it doesn't happen again. That is, at its core, what failure analysis is all about.

NOVA, the PBS series, produced the documentary "Why the Towers Fell" looking at the conclusions of the engineers and scientists on the government's exploration panel attempting to answer the titular question. In their findings there are a number of material science connections...

• tradoffs among cost, weight, and strength - particularly at 11:30
• design constraints - 12:45 (designed for impact of a Boeing 707, the largest at the time of design)
• mechanical testing methods (sheer, tension, vertical load) - 33:30
• heat softening of the steel - 37:45, 44:35 (and throughout in small mentions typically as "the heat would have softened the steel")
• failure analysis - all throughout, particularly at 45:00

NOVA also posted a website of information related to this episode, much of which is still online. Some links are starting to fail, however. The best of these are a very readable summary of the findings, the engineering history of the Towers, and a java interactive showing what metal atoms do as heat is applied.

This one's tough for me to post and was even tough for me to watch. I didn't have a direct connection to the tragedy of the Twin Towers, but I had at least one student who did, who knew someone on one of the planes. If it isn't already obvious, be aware that some of our students - or coworkers - may have closer connections and may still struggle with memories of the incident, of loved ones who were closer to the Towers, or even - like me - have memories of being in the Towers and being two or three relationship steps away from the tragedy.

Blacksmith demo at Eisenman Materials Camp 2012

Yeah, most of the time when we have high school students forging something, we aren't happy.

Here, though, we're thrilled to see the students at the Eisenman student material science camp doing a bit of forging.

I need to get up to one of the summer student camps sometime to see just how cool they are.

...or how hot in this case...

The All-New 2014 Sierra DureLife Brake Rotors

They're touting the fact that "GMC also uses a heat-treating process called ferritic nitrocarburizing" in their ads?

I'm thinking that the percentage of people who see that commercial who have even the faintest inkling of what ferritic nitrocarburizing is can be safely rounded down to zero.

Mini Materials Camp

Each time there is an MS&T conference, the ASM folks try to be there to run a mini-materials camp. The ASM folks invite local teachers to bring their classes (sometimes even paying for transportation) and see some of the glory that is materials science.

This series of videos shows the process of casting tin using a microwave oven. The process of sand casting is fascinating to watch and still an important industrial process.

The process is broken up into five parts - the remaining four of which are after the jump.

Today's post finishes with another demonstration from the mini-materials camp: the phase change of iron wire.

The mini camps aren't nearly a replacement for the week-long summer camps, but they're great ways to expose your students to materials science if you happen to be lucky enough to be in the area of an MS&T conference - like the Indianapolis folks are this fall (September 2013).

How It's Made Steel Forgings

The jokes just never stop coming from How It's Made. Their opening jokes are as corny as Kansas in August.

Our Tuscaloosa camp got to see an electric arc furnace at work at Nucor Steel. If ever you get the chance, do not miss seeing one of those at work. They're stunning and absolutely awesome.

The glowing blocks at 2:45 would be amazing to see in person, as would the forging press at 3:00. Wow...