This Should Be Impossible...

My name is Alec Steele. I am a blacksmith, amateur machinist and all-round maker of all-things metal. We make videos about making interesting things, learning about craft and appreciating the joy of creativity. Great to have you here following along!

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[YensiAl]

Hey, just to warn you of a bias you may have had when bend testing the hardenend samples. Billet 4, with the nickel, although it split appart, it did in a single place, and so no delamination, showing that it has the best layer adhesion from all the samples. So yeah, it failed more than the others, but for the others, when the outside layer cracked, it releases a large amount of the tension on the other layers, so they don't break that easely. For me what that test concluded is that the nickel billet has the best layer adhesion, and so is less prone to any kind of damages when under use, because a big unified piece is stronger than an piece that may break by layers. I'm not a professionnal on the subject, so I of course may be wrong.

[braidenmitchell]

Hey Alex, I'm a materials engineer. When we did a lab on solid state diffusion in uni, the diffusion was actually done by leaving the two metals in the furnace at temperature for 2 weeks to achieve proper diffusion. Pressing/hammering (like done in the video) would achieve better contact between the metals, but generally SSD is a far slower process than traditional forge welding. Hope this helps!

[mysa]

Alec! Time to partner with a university! Your approach is that of a phD student and your workshop just turned into the best available metallurgy lab!
I love your content, keep on enjoying what you do and share it with us... Thanks a lot

[notmyname]

You missed two important metals.

No. 1 is cobalt. It's know that Cobalt can bond very well with Titaniumcarbide and Titaniumnitrit. This is sometimes used to create carbide tipped tools. So it could be possible that Cobalt could bond with the Titanium. I think it could be better than nickel.

The other one is Tantal. It's known that Tantalcarbide fuses with Titaniumcarbide in carbide tipped tools. So I think it's worth a shot to try this metal as well. It is also very deformable, so it could perform great when bending it. It also has a lower CTE than the other metals you tried.

[genericconservative]

As someone who doesn't work with metal at all, but thoroughly enjoys the videos, those visuals with the colored cards about diffusion bonding were amazing!

[shurap]

To get rid of the brittle intermetals between titanium and steel, niobium spacers are needed. To prevent the formation of a carbide layer between niobium and steel, pure iron or nickel must be placed.

[En-Pea-Sea]

I think this is your best technical video yet. You have had some good and funny videos, especially when Jamie scares you, but this is just great education.

[felixinvita]

Mate I wanted to say that I absolutely love your explanations in this video with those little paper mockups. They're so easy to understand, well explained, and beautifully visualised in a lovely style with "practical effects" (compared to, I don't know, After Effects or whatever most Youtubers use for their graphics), which is something that I don't see too often on Youtube.

Kudos!

[muneeb-khan]

5:11 no vanadium? It’s one of the material referenced in the comments and it’s on the Wikipedia page for vanadium as a common intermediary for cladding steel and titanium.

[joshlego]

The problem with TI ( I did destructive lab testing on TI for aircraft for 2 years) is ALPHA CASE. It VERY quickly forms an outside scale that is INCREDIBLY brittle. It will legit just snap if you bend it with heavy case. In most TI Aircraft shops, the Case is removed with a chemical acid 3 part process, to remove the scale at a micro level. The lab (me) would measure the scale and then it would be removed over a pre-measured set of time/thickness with 3 diff acid baths. This allowed the TI to be able to be welded in a TI box that's filled with argon and it also allowed for press forming of the TI at heat. Very very very interesting process. I love this series you've started. The last part was inspecting the TI under a blacklight for pitting across formed areas to ensure solidarity with the press form. It has to be IMPECCABLE, or its scrap. Which happens more often than you think. This is why AC parts are so so expensive.

[albenk]

The important takeaway here is that the titanium layer is failing at the bend. No matter how good the joint if the pure titanium can’t handle the elastic forces it will fracture and that fracture will spread until it reaches the interlayer and then the fracture will move along the border causing the delaminating. The reason billet 3 bent is because the thick copper deformed itself inside the layer to allow the titanium to bend without breaking. This has nothing to do with the joint. What you need to pay attention to is if the joint fails before the titanium breaks, because you cannot change the elastic breaking point of titanium with any joint no matter how strong.

[Infraviored-lol]

Nickel had the best layer adhesion. The sample broke on half without delamination. Because of this, i suggest you nickel-plate the steel and the Titanium using electrochemistry. There will be a complete coverage of both metals and a very high surface quality.

[gregd]

I’m actually really enjoying this this series.

It feels part science education show, part blacksmith show and it’s a nice change of pace.

[thisisMeDM]

The shear seems to be slowly becoming an mvp of the shop. Seeing it in action several times in every video. Must be saving SO much time

[con-structsolutions]

21:54 Billet 4 2mm Nickel after hardening broke as one piece more so than all others. Pointing to a better bond imo. When thinking of rings of a tree, having a hard layer and a soft layer makes for a better overall material. I would take the sample to an edge and perform cut / durability testing.

[HisMajesty]

Hey Alec, I have a suggestion! You haven’t tried Aluminum. Apple uses solid state diffusion between Aluminum and Titanium in their new iPhones. Given Apple’s R&D budget, I’m sure they have verified that proper diffusion occurs between these two metals. Also, diffusion between metals is a process that takes a long time because the atoms need time to move through the very viscous metals. Diffusion only occurs fast in less viscous substances, which metal is not. You should be having the metals under heat for hours. And as for aluminum+steel, I’m not sure how well those diffuse together, you’d have to figure that one out. But great video btw, cheers! :)

[patricknowak]

The wavy layer patterns are a direct result of forging. I'm a metallurgical engineering in an open die forge shop with over 20 years of experience as well as a home shop blacksmith specializing in mokume. I have seen this behavior both on industrial and home shop projects. It has nothing to do with differences in CTE and everything to do with the friction between the work piece and the dies, the amount of metal under the die for any given blow and the depth of penetration of that blow. It happens with both hammers and presses and it happens with all metals, both those that are laminated and those that are not. It does not happen in metals that are processed by rolling only by press or hammer forging because the strain within the metal being deformed in that one blow or bite of the press is not uniform through the thickness. Rather, metal near the surface is affected by friction more than metal near the center of the cross section. This is why metal will bulge or barrel during forging operations, assuming you have enough power to make that happen.

[Zmbsmutd]

One thing that may explain some of the brittle failures in the outer titanium is a phenomenon called alpha case. When titanium is heated above around 700 C, the oxide layer on the surface can dissolve deeper into the metal. These oxygen atoms get mechanically wedged inside the titanium structure and makes it brittle and prone to cracking like you're seeing here. In industrial situations where they want to avoid this, they use strong acids (usually a mix of Nitric and HF acids, which are nasty), or heavily cooled grinding to strip the outer layer of titanium after any heating raises it above 700 C.

You may need to try messing with a surface removal procedure if you want to make it as strong as possible. The alpha case layer is usually only a couple thousandths of an inch (~10 micrometers) thick, so its not a ton of material that needs removing.

[TheIdeanator]

Alec, if you have trouble with heat loss (which im sure is a thing you'll experience), try putting some insulation on the dies as well as preheating them. We did that for inconel & titanium forging (big aerospace stuff) at my shop.

[brookmiller-lee]

Dude, your attitude is AMAZING! The metal deforms and messes up your hydrocutting machine, and instead of swearing (which most of us would do), you're like "Thats amazing!"
You are also very informed and intelligent. We'll done.