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The story of titanium

construction-physics.com

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Re: The story of titanium

#101

Post by johnwalkr »

petertodd wrote: post #50
MeImCounting wrote: post #43

Earlier quoted context omitted.

For most non-architectural design goals striking the right balance of toughness strength and hardness is generally what you want correct? I would imagine for building a bridge you care much more about elasticity and creep strength.

Also fatigue resistance. Bicycle design is a good example of where this matters: steel has a significant fatigue limit, and can endure cyclic stresses below that limit indefinitely. Aluminum has no fatigue limit, so any flexing is inevitably eating away at fatigue life. Thus aluminum bike frames have to be made much stronger and stiffer than otherwise necessary, to avoid bikes breaking unexpectedly due to fatigue. An…

For a rigid road bike aluminum can definitely be made stronger and lighter, even though what you wrote about fatigue limit is technically true. People like steel because they feel it’s more comfortable to ride. For mountain bikes, you will find almost zero steel bikes. Here the stiffness and lightness of aluminum (and carbon fiber at the high end) is almost universally preferred.

One advantage that adds to the potential lightness of aluminum and carbon fiber bike frames is manufacturing method. Aluminum is cheap to machine and hydroform into efficient shapes, and carbon fiber can also be layed up into efficient shapes.

Re: The story of titanium

#102

Post by johnwalkr »

janc_ wrote: post #80
petertodd wrote: post #50

Earlier quoted context omitted.

Also fatigue resistance. Bicycle design is a good example of where this matters: steel has a significant fatigue limit, and can endure cyclic stresses below that limit indefinitely. Aluminum has no fatigue limit, so any flexing is inevitably eating away at fatigue life. Thus aluminum bike frames have to be made much stronger and stiffer than otherwise necessary, to avoid bikes breaking unexpectedly due to fatigue. An…

Right now, top quality steel bike frames at the minimum bike weight allowed by the UCI are stronger than top quality carbon fibre bike frames of the same weight. Aluminum frames of the same weight would not be considered usable probably... (Pro cyclists would still use carbon fibre bikes because they can be made more aerodynamic).

That’s with a minimum weight imposed. Doesn’t change the fact that aluminum and titanium alloys generally have better strength-to-weight ratios than steel.

Re: The story of titanium

#103

Post by redman25 »

Vicinity9635 wrote: post #87

I have a titanium chainmail shirt: https://www.etsy.com/listing/505806057/titanium-chainmaille-... (me in 2nd pic) It weighs just 6.6 lbs. (the page says 6.5 but I had to have him add a bit cause I got too swole in the lats a couple of years ago.) It's fun to have someone try it on then watch them struggle as they can't figure out how to get it off lol If you bend over and stick your arms down it basically slide off…

Curious how durable a Ti shirt would be. Could it save you walking down a dark alley at night?

Re: The story of titanium

#104

Post by [deleted] »

TexanFeller wrote: post #99
pasabagi wrote: post #82

Earlier quoted context omitted.

That's true. On the other hand, people have been working with flint for longer than there have been people, and it remains fiendishly hard to make anything with it.

The ground is covered with flint arrowheads in various parts of TX that I’ve visited and/or inhabited. It’s really hard for me to imagine Indians crafting so many of them if it were that hard to work with.

[deleted]

Re: The story of titanium

#105

Post by lmm »

bch wrote: post #40
londons_explore wrote: post #28

Earlier quoted context omitted.

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

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…

> 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.

Re: The story of titanium

#106

Post by scythe »

MeImCounting wrote: post #37
saberience wrote: post #23

Earlier quoted context omitted.

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…

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 dent…

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.

Re: The story of titanium

#107

Post by kylehotchkiss »

q7xvh97o2pDhNrh wrote: post #74
kylehotchkiss wrote: post #29

Earlier quoted context omitted.

I wear a titanium ring too and keep my real one safely locked away. It’s an incredible metal that I proudly wear around. Mine cost about the same. I also have a titanium pocketknife (James Brand), carabiner, keyrings, pens, camera (fujifilm makes a few), and some beloved snow peak dishes. And the silly titanium iPhone. It’s such a great metal to make things to carry with.

Do you mind sharing where you got the titanium keyrings and carabiners? I've been searching forever for decent keyrings. There's a few carabiners (though the titanium ones are hard to find there too, and usually covered in obnoxious branding). But keyrings especially seem to be an under-served market. There's either (1) the usual mass-produced, flimsy, cheap garbage, or (2) something tougher and more expensive, but c…

Yes! I ordered these: https://www.amazon.com/Outus-Titanium-Rings-Split-Pack/dp/B0...

My super-scientific "is titanium" test involved trying to get a fridge magnet to stick to them. it won't, and a normal keyring will. Yes, that risks it being aluminum. Other reviews state they put one against their sanding machine and got white sparks which was an additional positive sign.

If you want to confidently get titanium, these: https://thejamesbrand.com/products/titanium-keyring

They also make the carabiner I mentioned: https://thejamesbrand.com/products/the-mehlville?variant=312...

And here's a beer bottle opener to complete your collection: https://thejamesbrand.com/products/the-tjb-bottle-opener-tit...

Re: The story of titanium

#108

Post by kylehotchkiss »

stevenwoo wrote: post #90
kylehotchkiss wrote: post #32

Earlier quoted context omitted.

Do your bikes have carbon forks or TI? when I looked at TI bikes for fun in the past, the carbon forks surprised me, seemed like that should have been titanium too. How has your mug held up? Has it been compatibly durable compared to steel vacuum mugs? Snow peak makes great products but leans more lightweight than durable from my experience with their dishware

Titanium needs to be in a bigger tube with thinner walls to take advantage of the properties compared to steel - the very first titanium bicycles used the available surplus tubing from defense/aeronautics industry that was close to steel bicycle tubing size and were notably not great until they used slightly bigger tubing and better titanium alloys. Forks have a couple of design features that make it hard to work wit…

This is super cool, I didn't realize the reason would be so complex. Thanks for explaining!

Re: The story of titanium

#109

Post by PakG1 »

londons_explore wrote: post #28
petertodd wrote: post #15

Earlier quoted context omitted.

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 the…

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

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

Re: The story of titanium

#110

Post by NickNameNick »

redman25 wrote: post #103
Vicinity9635 wrote: post #87

I have a titanium chainmail shirt: https://www.etsy.com/listing/505806057/titanium-chainmaille-... (me in 2nd pic) It weighs just 6.6 lbs. (the page says 6.5 but I had to have him add a bit cause I got too swole in the lats a couple of years ago.) It's fun to have someone try it on then watch them struggle as they can't figure out how to get it off lol If you bend over and stick your arms down it basically slide off…

Curious how durable a Ti shirt would be. Could it save you walking down a dark alley at night?

Looks like they're just butted rings, so you're relying on the rididity of each ring to resist opening up.

Welded or rivited rings would be much more robust. Especially vs piercing weapons, like arrows or fighting knives.

But much more expensive.

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