Is titanium stronger than steel?

[Elite Engineer]

I believe titanium is used in some armor or armor piercing rounds. On the molecular level, what makes titanium more resistant to damage (via blunt force) than steel?

 

if its not, then is there anything stronger than steel? (Not talking melting point)

 

~EE

[Sensei]

"The two most useful properties of the metal are corrosion resistance and the highest strength-to-density ratio of any metallic element."

https://en.wikipedia.org/wiki/Titanium

It has nearly twice smaller density than Iron.

Edited June 21, 2016 by Sensei

[John Cuthber]

It would be an odd choice for armour piercing- it's too light. But it has one interesting property, if fired through steel it will come out as a shower of sparks and cause damage inside whatever was armoured.

[swansont]

It would be an odd choice for armour piercing- it's too light.

 

 

Agree. Armor-piercing tends to go in the opposite direction: depleted uranium.

 

Two reasons Titanium is used in preference to steel are because it's lighter, and nonmagnetic.

[DrP]

I suspect a titanium shell with a heavy soft centre of lead or DU would be pretty good. Non magnetic would be good for countering future electric field type shield weapons.... but I think my imagination is running away with me now.

[Phi for All]

I don't like Ti for bladed weapons and tools, like swords and knives and chisels. It doesn't work as well as steel for a thin edge that sees a lot of work.

 

In addition to what swansont mentioned, Ti is often chosen over steel for better rust and corrosion resistance.

 

I believe I read where the US Navy's rail guns propel an armature (presumably affected by magnetism) that carries a projectile. I don't know what the projectile itself is made of though, and wonder if Ti would be a good choice, possibly for the reasons John Cuthber mentioned. On the other hand, as a kinetic weapon, would they prefer a heavier metal?

[swansont]

I believe I read where the US Navy's rail guns propel an armature (presumably affected by magnetism) that carries a projectile. I don't know what the projectile itself is made of though, and wonder if Ti would be a good choice, possibly for the reasons John Cuthber mentioned. On the other hand, as a kinetic weapon, would they prefer a heavier metal?

 

 

I imagine there's a sweet spot for the density to maximize the energy of the projectile.

[MigL]

Armor piercing rounds aren't designed for the whole shell to pierce.

They usually have a thin central projectile ( sabot in French ) which does the actual piercing and then fragments and sparks up anything inside the tank ( for example ), as John mentioned.

 

All I remember about Ti ( from Gr 13 Chemistry ) is that it burns in an N2 atmosphere.

[Phi for All]

They usually have a thin central projectile ( sabot in French ) which does the actual piercing and then fragments and sparks up anything inside the tank ( for example ), as John mentioned.

 

I thought the sabot were the outer casings that fit the bore of the launcher and then fragment away to reveal the actual projectile (the thin central part you're calling sabot). Have I had that wrong?

[Greg H.]

 

I thought the sabot were the outer casings that fit the bore of the launcher and then fragment away to reveal the actual projectile (the thin central part you're calling sabot). Have I had that wrong?

You are correct, Phi, the sabot is the outer casing around the actual projectile. A modern version is the APFSDS rounds used by the military. The linked article shows an image of the sabot separating from the penetrator.

Edited June 21, 2016 by Greg H.

[dimreepr]

You are correct, Phi, the sabot is the outer casing around the actual projectile. A modern version is the APFSDS rounds used by the military. The linked article shows an image of the sabot separating from the penetrator.

 

 

And there's me thinking it was a shoe, although I can see the logic.

[Sorsor_7]

Titanium is stronger and lighter than steel. However it is too light and not dense enough to go through armor. However materials such as hardened steel, tungsten, depleted uranium, tungsten carbide, etc., are used in armor piercing rounds. I believe you were thinking of titanium tank armor, which is very strong and basically impossible to penetrate.

[MigL]

You're right Phi.

Both sabot and flechette came to mind and since I couldn't remember which was which, I picked the more 'formidable' sounding one.

Damn those foreign languages !

 

Oh wait, French is supposed to be my second language.

( studied French for 7 yrs )

[swansont]

You're right Phi.

Both sabot and flechette came to mind and since I couldn't remember which was which, I picked the more 'formidable' sounding one.

Damn those foreign languages !

 

Oh wait, French is supposed to be my second language.

( studied French for 7 yrs )

 

 

Doesn't sabot translate as "wooden shoes", aka clogs? That may sound formidable if you're GW Bush in Baghdad, though.

[John Cuthber]

 

 

... GW Bush ...

On a related note,

here's the physics behind "dense is good"

https://en.wikipedia.org/wiki/Impact_depth

 

Of course if the stuff is dense enough you won't get as fast a muzzle velocity for a given set of launch conditions- it's a whole lot of trade offs.

 

[Sorsor_7]

Why is everyone talking about foreign languages?????????

[Phi for All]

Why is everyone talking about foreign languages?????????

 

Some projectile rounds need a sabot casing for the flechette inside. Sabot and flechette are both French words.

 

Then we started talking about density again, and you replied.

[dimreepr]

[Enthalpy]

Titanium isn't so strong, and definitely not as strong as steel.

 

The only strong alloy commonly available offers 820MPa yield strength for 4430kg/m³. A few alloys bring some 1300MPa but are unobtainable, and their strength drops soon with the material thickness.

 

Tempered steel brings as much, and if compensating the density, that is only 1450MPa. Steel tempered at 300°C brings as much, spring steel is far better, and Maraging offers 1800-2400MPa depending on the alloy.

 

I wish titanium would be better, but that's plain wrong. It's nice for resisting corrosion, for being nonmagnetic (but other solutions exist) - and it's horrible for galling, alas. The sad truth is that titanium has barely progressed in the last 40 years, while steel continues to improve at a good pace.

 

Better than steel, you have graphite fibre composites - and pretty much nothing else.

 

----------

 

Atoms define the Young and bulk moduli of alloys, but not their strength. This is a matter of alloying elements, of cold work and heat treatment; and of detailed compositions of crystals and intercrystalline phases. You may notice that most technological metals gets indefinitely weak as they get purer, iron and titanium too.

 

----------

 

For any projectile with a decent impact speed, and more so for kinetic impacters, only the density matters. Strength can't possibly make the round resist the impact, and has a negligible influence on the pressure on the armour. But stength does matter to resist the acceleration in the cannon, that's why the sabot is at midlength of the flechette.

Edited June 23, 2016 by Enthalpy

[Moontanman]

Titanium isn't so strong, and definitely not as strong as steel.

 

The only strong alloy commonly available offers 820MPa yield strength for 4430kg/m³. A few alloys bring some 1300MPa but are unobtainable, and their strength drops soon with the material thickness.

 

Tempered steel brings as much, and if compensating the density, that is only 1450MPa. Steel tempered at 300°C brings as much, spring steel is far better, and Maraging offers 1800-2400MPa depending on the alloy.

 

I wish titanium would be better, but that's plain wrong. It's nice for resisting corrosion, for being nonmagnetic (but other solutions exist) - and it's horrible for galling, alas. The sad truth is that titanium has barely progressed in the last 40 years, while steel continues to improve at a good pace.

 

Better than steel, you have graphite fibre composites - and pretty much nothing else.

 

----------

 

Atoms define the Young and bulk moduli of alloys, but not their strength. This is a matter of alloying elements, of cold work and heat treatment; and of detailed compositions of crystals and intercrystalline phases. You may notice that most technological metals gets indefinitely weak as they get purer, iron and titanium too.

 

----------

 

For any projectile with a decent impact speed, and more so for kinetic impacters, only the density matters. Strength can't possibly make the round resist the impact, and has a negligible influence on the pressure on the armour. But stength does matter to resist the acceleration in the cannon, that's why the sabot is at midlength of the flechette.

 

 

Isn't titanium stronger than steel pound for pound? I have read someplace that one disadvantage of titanium is that is cannot be forged. I'm not sure if that it cannot be forged at all or if it is very difficult to forge...

[swansont]

 

 

Isn't titanium stronger than steel pound for pound? I have read someplace that one disadvantage of titanium is that is cannot be forged. I'm not sure if that it cannot be forged at all or if it is very difficult to forge...

 

 

http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/the_titanium_advantage/

[Moontanman]

 

 

http://www.ibiscycles.com/support/technical_articles/metallurgy_for_cyclists/the_titanium_advantage/

 

 

https://industrialtalks.wordpress.com/2012/12/12/why-titanium-is-used-in-the-aircraft-industry/

[Enthalpy]

And the answer is: high-perf steel is stronger than titanium at identical mass. That's what datasheet say. 4430kg/m³ and 820MPa or 1200MPa for titanium alloys is only as good as 7850kg/m³ and 1450MPa or 2130MPa for steel, but Maraging steel achieves 2400MPa.

 

Forge: I don't know. But titanium alloys are pressed into bars and laminated, so I'd expect forging is possible. Fact is that larger airplane parts are molded and isostatically pressed, so forging is less convenient. Possibly the material loss make forging unattractive. As well, after good molding, you machine only the mating surfaces, the rest is net shape.

[swansont]

And the answer is: high-perf steel is stronger than titanium at identical mass. That's what datasheet say. 4430kg/m³ and 820MPa or 1200MPa for titanium alloys is only as good as 7850kg/m³ and 1450MPa or 2130MPa for steel, but Maraging steel achieves 2400MPa.

You haven't shown us a data sheet

[Enthalpy]

I hadn't search for them because I use this data regularly and know it by heart.

 

Here's a doc from Fuchs for titanium alloys. In German, MPa means MPa, mm means mm, and so on. The one alloy widely available is TiAl6V4 in state "geglüht" or annealed, offering 830MPa yield strength. The others are rare and made on order; Fuchs only indicates 1105MPa yield strength, up to maximum 75mm thickness - but I've already seen 1200MPa.

Ti_Fuchs_Warmausgelagert.pdf

 

For a doc about Maraging steel, search

Vascomax C-350

Vascomax C-300

yield strength is 2344MPa and 1999MPa.

These things do exist (for decades), I used them. They're tough, weldable, can be machined prior to hardening (and after to some extent). As opposed to ledeburitic steel, parts of Maraging steel can be designed just like tempered steel. Other, cheaper alloys may be less tough or get strong internal stress at hardening, which then limits the parts shape.