[danielodievich]

As a kid in my father's workshop we had several 4mm thick titanium plates, scavenged from some industrial stuff in USSR research facility nearby. I had a lot of fun getting my visiting friends tey to dent it with hammers. No matter how hard you struck it just didn't care. Only the oxidation patina would show some trace of impact. It was absolute magic to me. And so incredibly light!

[cyberax]

When the USSR collapsed, a lot of defense companies pivoted to civilian production. A factory in my town was producing titanium shovel heads.

They were awesome, unbelievably light, but very durable. They also made nice sparks when dragged across concrete pavement.

[myself248]

Decades ago, Sears sold magnesium stepladders. I've used one, and it's freakishly light, a 6-foot step ladder that you can walk around with balanced on one finger.

I've always wondered what a titanium one would be like.

[petertodd]

A lot heavier actually.

In an application like a stepladder, you have to work with certain minimum dimensions for the stepladder to be practical (eg rungs and sides have to fit in the hands nicely). You also have to have certain minimum thicknesses on the parts to have sufficient resistance to local deformation (eg dropping a hammer on the rungs). That forces the parts to be significantly larger and stronger than they otherwise would be. Which makes very lightweight metals like magnesium and aluminum the better choice, as you can make thick parts at the required dimensions at very little weight.

Climbing gear is a great example of this. Even though there's a segment of that market for which money is no object, the only use for titanium in climbing gear is certain specialized applications where corrosion resistance is important. Eg fixed gear mounted on sea-side cliffs. Because climbing gear has to have certain minimum dimensions to avoid damaging ropes, the very low density of aluminum wins over titanium's higher density/higher strength.

If you made a carabiner out of titanium it'd be stronger than necessary, and a lot heavier.

[TylerE]

This is also why aircraft use aluminum, despite the major downsides (finite fatigue life, mainly). There’s just no way steel would work (far too heavy). Titanium is awesome but a royal pain to work with. Carbon fiber is starting to come in but it has issues to - although they’ll be overcome with time.

[dredmorbius]

The Soviet Mikoyan-Gurevich MiG-25 was manufactured principally from stainless steel.

The result was a stunningly fast fighter aircraft, capable of Mach 3.2, though in practice engine overheating restricted operation maximum to Mach 2.83 (3,000 km/h), and even that for only 5 minutes at a time as the airframe and fuel would overheat. The MiG-25's mass necessitated huge wings (and overall dimensions), and limited maneuverability. Steel however provided better thermal-tolerance capabilities than aluminium, and lower cost and easier fabrication than titanium.

First flight 1964, introduced to active service in 1970.

That said, the aircraft is notable as an exception to your generally-applicable rule.

<https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-25>

I suspect carbon fibre would also have thermal limitations for high-speed aircraft.

[sufficer]

This aircraft also sparked development of the F15 which was superior to anything soviet for 10+ years

[j_apes]

Steel structure won't be necessarily heavier cause density and strength are almost thrice as much as aluminium ? I think the issue with steel is that it for the required strength, the structure would be too thin that it would buckle under compression much sooner.

[scheme271]

Titanium also doesn't have the resistance to abrasion that other metals have. There's stories of titanium bike frames being ruined because the rear tire was mounted incorrectly and ended up rubbing on the frame during a ride.

[londons_explore]

If you can 3D print titanium, then you can make a honeycomb structure overcoming this problem.

[bch]

What is the response to stress by this build method? Will it fail gracefully over a lifetime of stresses? Any single big stress-event?

In terms of (rigid, diamond-frame) bicycles, this is why I’m still firmly in the steel camp. No aluminium, no carbon; just steel. It really does have an excellent combination of nice ride quality, low weight, high strength, good failure mode (I’ve broken a few frames, and they tend to just bend/sag, vs the rapid unscheduled disassembling of carbon/Al).

[londons_explore]

I can't comment on the plasticity of titanium.

But complex microstructures can be designed to have non-sudden failures. Eg. you could ensure that a visible crack appears at 0.75x the ultimate strength, yet doesn't fail till 1.0x the strength.

You can also design structures so that a 'crack' is either 1mm wide or not there at all (ie. no hairline cracks).

such features of microstructures are not free though - you will lose strength/weight to get them.

[lmm]

> In terms of (rigid, diamond-frame) bicycles, this is why I’m still firmly in the steel camp. No aluminium, no carbon; just steel. It really does have an excellent combination of nice ride quality, low weight, high strength, good failure mode (I’ve broken a few frames, and they tend to just bend/sag, vs the rapid unscheduled disassembling of carbon/Al).

Bicycles don't have the minimum size problem GGP is talking about. Titanium is pretty much the perfect frame material (if you can afford it) - all the nice things you list (a bit stiffer than steel, but ride quality is still decent), but substantially lighter.

[PakG1]

Coincidentally, you can. https://www.sciencedirect.com/science/article/abs/pii/S00260...

[tako]

NI think AI assisted development needs comments to make better informed decisions about the code Needed to accomplish the task.

[BobaFloutist]

Can you 3D print metals yet? That sounds quite difficult.

[mhb]

Prototyping - Metal 3D Printing - Dan Gelbart

https://youtu.be/nyYcomX7Lus?si=E-B5VkFeX9W0Twc4

[smazga]

Sort of! https://thevirtualfoundry.com

Not directly extruding it, but the end result is metal.

[jabl]

> Decades ago, Sears sold magnesium stepladders. I've used one, and it's freakishly light, a 6-foot step ladder that you can walk around with balanced on one finger.

As a slight aside, magnesium is also a very interesting material. It might be we're on the cusp of a major expansion in magnesium usage due to recent advancements

- Mining from seawater (about 1 kg Mg in 1000L of seawater), or existing brine tailings from other extraction activities. With cheap solar electricity this might drive the cost down considerably (below the extremely dirty production methods being used today in China), providing carbon-emission free production of essentially unlimited amounts.

- thixomolding, a die-casting / injection molding-like process where the material isn't completely melted (thixotropic state), producing parts with much less porosity than traditional die casting.

- New alloys that are less prone to fires and corrosion.

For slightly more details, see https://www.youtube.com/watch?v=OIv_Rfl0L_A

[speed_spread]

Magnesium from mine tailings https://anrweb.vt.gov/PubDocs/DEC/GEO/TechReports/VGTR1998-1...

[justinator]

I had to do a double take on your "about 1 kg Mg in 1000L of seawater" stat, thinking it was for titanium, rather than magnesium.

For those curious, titanium is present in sea water, at 1 ppb! (magnesium is 1300 ppm)

[SV_BubbleTime]

Aluminum and magnesium are lighter than titanium at the same strength.

The idea is you can use less titanium in the application you would use aluminum, but this has limits. If your ladder was .200” wall thickness, you might in theory get away with a .070” titanium for the same weight, but you start running into mechanical stresses or assembly issues or manufacturing.

Titanium is useful when you need internal volume - most recently as an example by Apple. Aluminum was fine, but had thick walls. Steel allowed thinner was but was heavier. Titanium allowed for thin walls and more internal volume, but at a higher cost.

Basically, if you don’t have a size limit, aluminum is great! But most things have size limits, and titanium allows you to trade size for cost.

[Skunkleton]

The iPhone 15 pro is mostly aluminum. There is about a 1mm thick band of titanium around an aluminum frame.

https://www.apple.com/newsroom/2023/09/apple-unveils-iphone-... https://www.youtube.com/watch?v=S_W73ouKtjU&t=605s

[SV_BubbleTime]

And that makes perfect sense.

Thick walls on the iPhone are what are going to prevent X Y area which I suspect they need more than thickness.

[Skunkleton]

Seems like marketing to me. They got rid of the stainless steel frame from previous models, switched back to aluminum, then added a pointless band of titanium so they could say Titanium in their marketing.

[dreamcompiler]

Magnesium stepladders are great until one catches on fire because you try to weld something onto it or get it too close to a welding torch. Then things get spicy.

[postmodest]

Plus: doesn't magnesium oxidize more readily than other metals? I would worry that grandpa's magnesium ladder is a death trap.

[AlotOfReading]

Bulk metals are extremely difficult to ignite and magnesium in particular forms a very strong passivation layer on the surface as soon as it touches the air. Unless you're doing wildly inappropriate things like welding on it (tip: don't do this with any ladders, regardless of material), it's fine.

[cyberax]

Huh. Now I want to buy a magnesium ladder and set it on fire.

[dreamcompiler]

If you do, take it out into the middle of nowhere first because you won't be able to put the fire out (unless you bring a Class D extinguisher--good luck finding one of those at your nearby hardware store). Don't put water on it because that just makes it burn hotter.

[hef19898]

Damn, imagine having a titanium shovel! I want one!

[avs733]

https://nearzero.co/products/shovel

They exist! Meant for backpacking/back country work.

I spent a summer as a wilderness search and rescue intern/volunteer/grunt/mule during college and was shocked at how much weight could have been saved with better gear. There’s just a minimal market for it.

[amluto]

That company sells titanium pots, too. And they say “ Titanium leaves no metallic smell or taste.”

I don’t believe it. Titanium is, mechanically, a great material for a lightweight pot, but in my limited testing, I don’t think it’s inert enough. Green tea in a titanium pot is especially nasty.

[WillAdams]

This is actually a plot point in H. Beam Piper's _Little Fuzzy_:

https://www.gutenberg.org/ebooks/18137

the audiobook read by Tabithat is just about professional quality and is highly recommended:

https://librivox.org/little-fuzzy-by-h-beam-piper/

[OfSanguineFire]

In the backpacking and bicycle-travel community, titanium pots are widely regarded as good only for boiling water in, since they don't distribute heat as well as aluminium for more complex cooking.

[amluto]

I’m well aware, but I don’t really believe this :). As far as I can tell, no very thin pot or pan distributes heat well [0], and no very thin pan cleans up well from cooked-on food when the cleaning supplies at hand while backpacking.

[0] Concretely, this means that, when cooking solid food, the parts of the pan where the food isn’t sinking heat adequately get too hot.

[therein]

I had similar experiences with titanium cookware. Could it be acting as a catalyst to something that would otherwise not happen?

[amluto]

I don’t know.

My current favorite cooking surface is the coating used on Hestan Nanobond. It’s sold as “titanium” but, from reading the patent, I think it’s a bunch of layers of CrN, TiN, and AlN, applied by PVD in a process optimized to produce an attractive gray color that looks a bit like metallic titanium. It seems very hard, very durable, and does not obviously react with any kind of food. (And even if it did, unless something oxidized the Cr to +6 and made it soluble, nothing that might leach out seems likely to be harmful.)

The patent seems to expire fairly soon, and maybe the process will take off. I wonder if this coating could be applied to a lightweight titanium pot with good results.

[tuatoru]

Oh, there's a market for lightweight backpacking gear, all right! Check out Backpacking Light for in-depth reviews.

Garage Grown Gear has some of the trendy light and ultralight stuff.

1. https://backpackinglight.com/

2. https://www.garagegrowngear.com/

[saiya-jin]

Mountaineering ice screws. Its a dream for pro alpinists, since you have to drag every gram up there in thin air, so focus on weight saving is extreme, ie drilling holes into aluminum spoons before 8000m expeditions was normal in 70s-80s in eastern Europe block. Normal stainless steel ones are much heavier.

[petertodd]

Those must have been soft hammers. Titanium isn't magic. It's neither as hard, nor as strong, as steel. It's a lot lighter, which makes it a wonder material in certain applications that can take advantage of it's excellent strength-to-weight ratio. But if max hardness, or strength at a given size, is what you are after, without a weight constraint, steel wins.

[saberience]

I mean, I'm no materials scientist but one google tells me that Titanium is AS strong as steel but much less dense. I just browsed through the top 10 Google results and everyone states that titanium is roughly equal to steel in strength but with various other benefits. So your comment is definitely off-base somewhere, you make it seem like steel is much stronger, which clearly isn't the case.

[petertodd]

Read this for starters: https://www.thomasnet.com/articles/metals-metal-products/ste...

"When comparing the tensile yield strengths of titanium and steel, an interesting fact occurs; steel is by-and-large stronger than titanium."

Many people confuse this issue, because they're actually talking about measures of strength/weight ratios, on which titanium does really well. But if you are size limited rather than weight limited, steel is often a better material than titanium even when cost is no object.

[saberience]

Every source says that titanium is as strong as the most commonly used steel. Sure if you're going for lesser used alloys of steel you may as well compare to lesser used alloys of titanium. Or just compare iron with titanium, as that's really comparing one element with another, and is the "fair" comparison.

And anyway, your original comment suggested someone was totally in the wrong for thinking a 4mm titanium plate was strong, which is obviously incorrect. 4mmm of titanium plate is clearly going to be really strong and resistant. They wouldn't make plane engines from it if it wasn't.

[petertodd]

> They wouldn't make plane engines from it if it wasn't.

...but they don't! Jet engines can only use titanium for certain low pressure, low temperature, sections. The high temperature parts are made from nickle/iron-based superalloys. And aluminum still gets significant usage, because for many geometries an aluminum part has a better strength/weight ratio.

Like I said, titanium is strong. But it's not magic. Stronger than any aluminum alloy, weaker than commonly used steel alloys. Hitting a 4mm plate of titanium with a hammer just isn't a very special experience. I've done it.

Hitting a 4mm tool steel plate definitely can be a special experience. Because it's so strong and hard that you could easily cause the thing to shatter, sending sharp shards in unpredictable directions...

[MeImCounting]

No the parent is correct. Steel is by and large stronger than titanium of the same size. Pray tell what is this "most commonly used alloy of steel"? Because just fyi different steel alloys are used for different applications just like different titanium alloys are also used for different applications.

Titanium has excellent strength to weight properties compared to steel. A 4mm titanium plate would absolutely be dented by common shop hammers. This doesnt mean that "titanium isnt strong" it just means they have different material properties.

[scythe]

Steel has a range of strengths. The "most commonly used steel" is probably just mild steel and yeah Ti-6Al-4V is going to be the rough equal of mild steel on strength broadly assessed. But a high strength steel alloy will be three times that strong, and titanium can only be pushed so far.

[petertodd]

Exactly.

Indeed, if your design goal is strictly "don't get dented when hit by a hammer", the "strongest" material could easily be a good synthetic rubber!

[nullc]

Titanium is quite expensive. I don't know if it makes sense to compare it to mild steel and not compare it to fancier steel selections which are still much less expensive than titanium and also much easier to work.

AR500 has a HRC of 47, modulus of 220 GPa, and tensile strength of 1740 MPa. Ti-6Al-4V is 37, 113.8 GPa, and 880 MPa respectively. The AR500 costs less than half as much as the Ti, and is much easier to work (though obviously working will degrade the properties).

The titanium is super really light, however... so the choice of material will depend on how relatively important weight is vs size and how simple your geometry is such that the added difficulty in working with Ti doesn't add problems.

Obviously there are also other grades of Ti too, but I think the comparison generally holds: If you don't care about weight/mass there is a steel selection which will be stronger, cheaper, and easier to form.

If you do care a lot about weight, an aluminum alloy often comes out the winner unless you just don't care much about costs or have fatigue concerns.

[AlotOfReading]

Steel's strength varies by orders of magnitude depending on the alloy and heat treatment. It's an incredibly flexible family of materials. Some members of that family are far stronger than anything in the titanium family, e.g. 4340 steel has a nominal yield strength of >1800 MPa, compared to <1300 MPa for Ti 10-2-3.

[saberience]

We're not talking about exotic and expensive varieties of steel though. We're just talking about "general" or common steel and comparing it to unalloyed "common"/"general" titanium. Remember, Steel is itself an alloy, Titanium is an element.

If you start comparing Titanium alloys to Steel then the comparison gets even harder. Titanium alloys are in general stronger than steel as well as much lighter and more corrosion resistant.

[petertodd]

> We're not talking about exotic and expensive varieties of steel though.

4340 steel isn't exotic. It's one of the most commonly used grades of steel out there, and it's much cheaper than titanium. There are steels out there with significant stronger yield strengths too. Meanwhile the highest yield strength of any Ti alloy is <1300MPa.

Titanium is still a really great material in certain applications. But it's not magic. You have to use it intelligently in the right application to get a benefit from it.

[bch]

The family of materials we call steel is so fantastic, it almost a shame it’s so ubiquitous that we take it for granted. If it were invented today the front page of HN would be loaded with stories of this miracle material.

[MeImCounting]

Pure elemental titanium has much less desirable material properties than various titanium alloys which are what you encounter most commonly. It is very uncommon to encounter elemental titanium outside of a chemistry lab.

[metal_am]

Grade 1 is still pretty common for ultralight backpacking items like pots and pans due to its ductility.

[cwillu]

So called “mild steel” would be far more accurately called “iron”, the carbon content is insignificant.

[dreamcompiler]

The carbon content of mild steel is low but not insignificant. Pure wrought iron [0] is a dream to forge and it has a huge grain structure. It's more ductile than mild steel but it's also not as hardenable or tough as mild steel [1]. That little bit of carbon in mild steel makes a big difference.

[0] I mean real wrought iron -- the almost 100% elemental stuff -- like the Eiffel tower is made of. This is practically unobtainable today. The "wrought iron" you commonly see for sale nowadays is always mild steel. And "cast iron" is actually very high carbon steel, not iron. Cast iron so high in carbon that it's brittle and cannot be forged or easily welded.

[1] It's a myth that mild steel cannot be hardened. With a proper wetting agent added to the quench, you can harden it significantly.

[ClumsyPilot]

> We're not talking about exotic and expensive...

> "general" or common steel and "common"/"general" titanium

Why would you compare 'trash-quality' steel vs exotic and expensive material like Titanium?

That does not make any sence.

[scythe]

Wikipedia:

>4340 steel is an ultra-high strength steel

https://en.wikipedia.org/wiki/4340_steel

The alloy composition calls for 0.2-0.3% molybdenum and expects accuracy to within a few per mille for ten elements. Moly is considered so important that there are entire towns in the United States established to mine it to secure the military supply chain.

[justinator]

Is this true? From the Wikipedia article, the two mines that produce molybdenum as the main product are the two in CO, Henderson and Climax. They have no towns associated with them. Climax is near Leadville, but Leadville existed as a mining town before molybdenum was being mined at any scale. The other mine isn't close to any town that has more than a trailer park of people.

The others mine molybdenum as a byproduct of copper. I guess you could say the Bagdad mine has a company town, but it wasn't made to secure the military supply chain 140 year ago.

[rowanG077]

There are definitely steels that lose out to grade 5 Titanium. There are also steels that beat all Titanium grades. It's not so simple to say steel is stronger then Titanium. Some steels are stronger then titanium. Some Titanium grades are stronger then Some steels.

[robotomir]

I had a titanium Tissot watch and it scratched easier than steel watches.

[mkii]

Yep, I have a couple titanium watches too. I find that the scratches picked up every here and there adds to the "character" of the piece. Like it's living life with me.

[Turing_Machine]

The article mentions that the Soviet Union had lots of titanium ore, and also that it was heavily used in the A-12/SR-71 family of aircraft.

I remember reading elsewhere that the CIA set up a bunch of front operations across the world to buy titanium (or maybe titanium ore) from the USSR without them finding out what it was being used for. They didn't want the "Ship to:" part of the order form reading "Lockheed Skunkworks, Burbank Califoria". Heh.

[pests]

Elsewhere would of course be the excellent "Skunk Works: A Personal Memoir of My Years at Lockheed" by Ben Rich.

Highly reccomended and goes into further engineering and design challenges of the RS-71 Blackbird and its titanium construction.

[dendrite9]

There's an interesting story about trading Boeing aircraft design knowledge for Soviet titanium design knowledge during the cold war. https://www.smithsonianmag.com/air-space-magazine/the-titani...

[muz754]

Some hammers might not be that hard - you don’t want it to blow up in your face if you’re hitting a hardened steel tool.

[psd1]

I do not like my hammer hard!

I do not like a face of shard!

I like to whale upon a tool

A shattered hammer is not cool!