“For Art” Does Not Appear To Suffice


It’s probably a good thing that there are lots of regulatory hurdles that prevent someone from getting easy access to high explosive. The forms you need to fill out to get licensed as a blaster in Pennsylvania are pretty limited, there’s only one option for “why do you want to become a certified blaster?” and that’s “mining.”

Apparently there is a shortage of certified blasters, but that’s understandable – mining is dangerous, nasty, environmentally destructive work. The regulatory structure is also interesting: you don’t get to apply for certification until you already know how to do explosive demolition work, which means (I assume) you have to get a job working as an explosives tech first and then get certified if you don’t blow yourself and anyone else up in the first year. It seems darwinian, which is not necessarily a bad thing.

The odds I will pursue blaster certification are effectively zero; I have better things to do with my time. But here’s why it’s interesting: if you take two metals and clean/surface grind them, put them in a frame that holds them steady and cover them with a couple of inches of ammonium nitrate high explosive, then set it off – they weld together. It doesn’t matter if they’re metals that would normally not want to weld, they weld anyway when gently encouraged with a supersonic hammer-blow of high explosive detonation. It also turns out that if you put your detonator/blasting cap at one corner of your welding stack, the explosion moves as a very fast wave through the explosive media and the wave perfectly squishes the metals without inclusions or air gaps because the air is driven out of the space between them “rather quickly.”

So, you can have a plate of 1″ thick steel clad on both sides with aluminum, or titanium, or… whatever. Incompatibility in welding means nothing to a really really big hammer. Best of all it doesn’t even heat your materials (but it flexes them!) so you don’t have to worry about decarbonizing your steel.

I’m just fantasizing, I know, but who wouldn’t want to take a thin sheet of tungsten carbide and laminate it between two pieces of titanium, explosive weld the mass, and then water-jet cut a katana out of that and mill it down with a couple of nice bevels? Sure, it’d be hard to sharpen, so you’d better be careful when you chop a car’s engine block with it.

This stuff is probably pretty expensive, because of the infrastructure cost; I suspect that if I called them up to enquire about making a block of stainless steel/aluminum damascus, they’d just hang up the phone.

From NobelClad’s website: [nc]

In 1994, we became Dynamic Materials Corporation, and two years later, purchased the explosion welding business of another industry pioneer, DuPont. We also assumed the lease on DuPont’s Dunbar Mine, a former limestone mine in southwestern Pennsylvania that was converted into a unique explosion welding shooting facility.

Arrrrgh! It’s a real honest-to-goodness “mineshaft gap”!

The American Welding Society has some more information on explosion welding. Including the fact that the explosion may cause ripples in the material that are perfect for damascus blades. [aws] Joking aside, I suspect it alters the crystallography of the steel, too. Wouldn’t it be amazing if the explosion also took the steel to a bainite state in the process, and left it there?

The force of acceleration temporarily transitions the colliding pieces into a plastic state. That brief moment of malleability allows metals to fuse together at an atomic level. Although the process creates strong and clean welds, it also produces incredibly loud noises and wasteful byproducts that limit where the process can be performed. In fact, explosion welding must be conducted in extremely remote locations.

Done improperly it can transition all kinds of things into a temporarily plastic state.

I’ll be too busy doing stuff the traditional way, for the next ${however many} years, and I will resist the temptation to pursue this any further. Doubtless I’d wind up getting waterboarded in some hell-pit because they’d mistake me for a terrorist, and not an artist. Real terrorists wear black berets, don’t’cha know, they don’t drive around in white vans covered with Trump stickers. Oh, hey that gives me an idea…

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I live in fracking and mining country and there are places all around that sell explosives for the miners; there are trucks full of the stuff that go right down the road near where I live (one reason I live way back from the road, in fact!) I am not going to contact any of them; I suspect their immediate reaction is to call the FBI. But, geeze, there’s an open strip-mine right at Pottersdale 12 miles from my place, we could just go down there with a couple sheets of different metals and blow us up some damascus. Aw, please?

Comments

  1. says

    Interesting. I never heard about this before. I bet it changes the structure of the steel though, so hardened steel probably would not remain hardened. it might even change into completely different crystal structure. Are there metallographic studies of these joints on hardened steel?

    I am not sure whether tungsten carbide would “weld” this way with titanium, since tungsten carbide is not a metal. AFAIK it is brazed onto steel tools, not welded.

  2. Reginald Selkirk says

    linky

    Explosion-bonded aluminum to stainless-steel-transition blocks are used not only to facilitate welding, but also to provide a smooth cross-section transition from the complex extrusion cross section to a simple rectangular one.

    Figure 2.2.7: Conceptual vacuum chamber design. Stainless-steel (SST) UHV flanges are
    welded to the Al extrusions via explosion bonded SST/Al transitions (A)

    This is one layer of steel and one layer of aluminium. I am not sure if it could handle the layering and folding necessary for Damascene.

  3. says

    Charly@#1:
    I am not sure whether tungsten carbide would “weld” this way with titanium, since tungsten carbide is not a metal. AFAIK it is brazed onto steel tools, not welded.

    I hear the siren song of science calling me.

    However, I suspect that buying a couple pounds of tannerite would get me on the wrong list.

  4. kestrel says

    Oh, boy… “Don’t try this at home, kids!” That metal block with the waves is really beautiful. But it does seem like you’d need to own a mine and some incredible equipment to pull it off. Maybe they take requests? Wouldn’t hurt to ask.

    And yes, I can just imagine how this process could “transition” lots of unintended things if not done exactly right.

  5. MattP (must mock his crappy brain) says

    It can only bond materials that can survive plastic deformation, so tungsten carbide and ceramics are all right out. Might be able to get some of the shattering carbide sheet embedded in a sandwich of metal, but that would be more tungsten carbide hacksaw blade than carbide end mill and would quickly delaminate if the carbide layer is too thick and/or too few gaps for the outer metal layers to bond together.

    Brazing would definitely be easier, safer, and much more likely to succeed, but would not help with the inherent fragility of the carbide layer that would cause it to break within the sandwich the first time you flexed it even a little bit. There would also be the problem of thermal expansion rates: if the titanium and carbide rates are not sufficiently well matched and/or materials not preheated to appropriate temperatures then the carbide in the brazed sandwich would break before it finished cooling to room temperature.

  6. lorn says

    Fascinating.

    I studied the use of explosives to destroy, sometimes in remarkably controlled and detailed ways, but never to assemble anything. We used two isosceles triangles of sheet explosive to cut a long 6″ diameter alloy steel rod. Placed on opposite sides and timed to go off simultaneously they sheared the rod so cleanly, and with no observable distortion, that it looked like it was done in a machine shop.

    Explosive welding. Cool deal. Thanks for highlighting it for me.

    I’ve long wondered about another process: plasma deposition. A decade, and a bit, ago it was experimental and I had a short conversation with a materials science guy about how it would be possible to deposit a layer of diamond onto metal in advantageous locations and pick up localized wear resistance and heat dissipation capacity. Diamond has advantages in both areas.

    More practical to blade craft I always wondered what a layer, or mesh, of diamond a few microns thick might get you.

  7. Curious Digressions says

    If you’re really interested, maybe NobelClad would let you job shadow, possibly collect scrap in exchange for a blog exclusive. A lot of companies will humor enthusiastic amateurs.

  8. voyager says

    Hey, you never know until you ask. I have a plan.
    First, find a phone booth (they still exist don’t they?) that isn’t watched by camera. This step may take some time, but you can use some of that time productively by creating a good disguise. Winter is a good time for this because it’s easy to incorporate a hat without being noticed. Get shoe lifts, too. Or maybe cowboy boots because they might help change how you walk, but just to be sure you should also practice a new walk. You may wish to consult with the Ministry of Silly Walks, but I should caution you that taking their advice might be ill-advised. Best not to draw attention to yourself. Since you will be conversing with someone a change in voice will be necessary. Keep it simple, avoid accents and practice, practice, practice.
    Now it’s almost time to make that call. Pick a busy time of day and park around the corner from the phone booth. Leave any devices at home that could track your location. Make sure you have adequate coinage and don’t use any of your cards in the area. Be polite and deferential once you’re actually talking to a real person and keep the call short. Good luck.
    Or, you could do like Curious Digressions suggests and just go full on geek.

  9. robert79 says

    So would bigger explosive mean an even better weld? Will, at some point, someone come up with an actually practical use for an H-bomb?

  10. John Morales says

    Crip Dyke, pollution aside, Project Orion was only ever a speculative idea, and it was A-bombs, not H-Bombs.

    (Too much boom is too much)

  11. Sunday Afternoon says

    @lorn, #7:

    Sputtering (plasma deposition for HDD components) has been around for significantly longer than a decade and a half: https://en.wikipedia.org/wiki/Sputter_deposition

    Metal alloys and oxide mixes are sputtered onto the substrates, followed by very thin carbon overcoats (much thinner than a micron) which are used to control the head/medium interface. DLC (diamond-like carbon) is deposited on both the platter and the air-bearing surface of the “slider” to provide wear robustness as well as a barrier to protect the more reactive metals underneath the carbon layers.

    I found what looks like a nice review article on the history of sputtering: https://avs.scitation.org/doi/pdf/10.1116/1.4998940

  12. MattP (must mock his crappy brain) says

    @John Morales
    A-bomb and H-bomb are both misnomers. All nukes derive the vast majority of their yield from fission with a ridiculously high yield ‘H-bomb’ simply being a multi-stage ‘A-bomb’ fission device that uses a small fission stage to sequentially trigger later fission stages too large to practically trigger with conventional explosives. The ‘H-bomb’ name came from intentional misinformation related to various fusion-boosted fission designs that use some amount of fusion to increase neutron density which can improve yield/efficiency (e.g. weapon armed by pumping tritium gas into a hollow plutonium pit prior to implosion. During implosion, the tritium is compressed and heated enough to cause fusion that releases a burst of neutrons to cause criticality in the surrounding plutonium pit insufficiently massive to achieve criticality without that additional burst of neutrons).

    …I love being on all these watch lists…

  13. Andrew Dalke says

    Do you know about dentonography? Quoting Wikipedia, “Detonography is a method for sculpting metal with plastic or other explosives. Essentially a form of giant printmaking, with the explosive acting as the stamping press, it was created by Evelyn Rosenberg in 1986 with the help of the engineers of New Mexico Institute of Mining and Technology in Socorro, New Mexico.” Her web site is http://www.evelynrosenberg.com/ . Here’s an article about her and the art form – https://www.copper.org/consumers/arts/2007/july/Copper_Catalyst_Evelyn_Rosenberg_Explosive_Art_Detonography.html . I learned about it from a Smithsonian magazine article around 1989, but I can’t find that article.

  14. says

    Andrew Dalke@#2:
    Do you know about dentonography?

    Yes; I believe the idea came after the invention of shaped charges (which originally came from an explosives engineer who discovered he could ‘etch’ his name in armor plate by carving it into a block of explosive pressed against the plate) – there has been considerable use of explosives to shape things including explosively-formed penetrators.

    I wonder if wet sand could be used as a mold for EFP copper. Darn that’d be fun.

  15. says

    felicis@#19:
    Giving you plenty of experimental room – and capacitors and low-induction switches are a lot easier to come by than explosives.

    They’re probably even more dangerous, too!

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