Titanium Usage Growing and Where? 1

[cj811]

Titanium gets mentioned as being a metal for the future and I wanted to know if people (engineers) are seeing this in practise? I feel titanium is occasionally indie projects more for marketing reasons (bullet proof golf clubs/business card holders..) and there obviously the common applications e.g. heat exchangers that have always been ti. However with teslas cars using a titanium underbody I wondered if things really are moving increasingly towards this metal.

Somewhat of an open question but is anyone seeing titanium being chosen as a metal of choice ? Particularly is it moving to replace steel in any way ?

 

[ornerynorsk]

molten, I perhaps should have opted for a more expensive material in a similar situation, although mine was entirely intended as a joke. A piece of quartz epoxied to a beer can pull tab was not well received, and the opportunity to present a more suitable specimen somehow never materialized, things just when downhill after that. All for the good, though. The current missus is a peach and a keeper, for sure.

Back on topic, it will be interesting to see, as usage does increase, if sufficient improvements to extraction and refinement will occur to the degree that aluminum once experienced. If memory serves, aluminum was considered a precious metal not even two centuries ago.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

 

[JohnRBaker]

When they were nearing the completion of the Washington Monument in 1884, they capped it with a 100-ounce pyramid of pure Aluminum, the largest item ever cast in Aluminum at the time, as part of the lighting-rod scheme protecting the monument. At that time the price of Aluminum was about the same as Silver and the use of this expensive piece of material was seen as an outrageous waste of taxpayer's money but the architect responsible for the design wanted to finish the monument with something which represented the emerging engineering and manufacturing power of America.

Note that per the spot price of finished Aluminum at the close of business yesterday, that 100-ounce object would be worth less than $6.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[moltenmetal]

ornery- the fact that she kept, and in fact still wears, that ring I made, is an indication that mine is a keeper too. She passed that, and many other subtle tests that in fact weren't really tests at the time, just me being me. But she has a passionate hate-on for my car (see the Hobbies forum), and I had the car first...oh well, nobody's perfect!

 

[EdStainless]

When you talk Ti you need to make a distinction between CP (commercially pure) grades such as the ones used for heat exchanger tubing, grades that are alloyed for corrosion resistance (often with Ru or Pd, these are very uncommon alloys), and the grades that are designed for high strength by heat treatment (usually with Al, V and others).
First, only about 2% of Ti mined is used as metal, almost all of the rest is used TiO2 pigment.
It used to be that people built plants that produced CP material, and used it as feedstock for the high strength aerospace grades.
This changed when China began building plants. They wanted less expensive CP material for industrial use (and consumer use) and they built plants that made CP that was not suitable for remelting into aerospace grades. The CP material makes up about 85% of all metallic Ti used.
As a result CP prices are very low ($7-8/lb, about double that of Cu), but high strength aerospace grades are still as expensive as they have always been. Depending on the alloy and product form they can range from $25-75/lb.

The biggest design issue with Ti is the low modulus, only about 15kksi compared to steels (and stainless) at 30kksi.
Ti also has issues with the properties being different in various directions. Rolled plate has different strength and modulus in the longitudinal, transverse, and thickness.
Ti also (like Al) does not have a cleanly defined fatigue limit. Hence when cold worked Ti3/2.5 is used for hydraulic tubing on aircraft it has a finite service life that is much less than that of the airframe. At the same strength 21-6-9 stainless tubing may be 35% heavier, but it has an infinite fatigue life under the same design limits.

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Plymouth Tube

 

[davefitz]

Titanium used to be considered a "strategic" material in that most of it was sourced from the former USSR. With the recent political issues with Russia I would guess the availability of Ti will drop. For most of its applications there are alternatives. For condenser tubing one can use Sea-cure duplex stainless steel. For consumer items one can use graphite epoxy. For U-2 spy planes- no likely substitute, therefore we probably have a strategic stockpile. For non-magnetic sub hulls- not sure- probably some form of SS or composite material or geopolymer.

"Whom the gods would destroy, they first make mad "

 

[moltenmetal]

Interesting point about the fatigue limit, as it explains what I saw on one unit we shipped: a piece of titanium 1/4" OD tubing inserted into a Swagelok fitting, snapped off clean at the junction between the tube and the nut, even though the piece itself didn't have a particularly long unsupported length. Vibration in shipment had cycled the tubing enough that it fatigued and failed. We never see failures like that with ordinary stainless steels, and some plants we ship have literally thousands of such joints.

 

[drawoh]

moltenmetal,

That sounds extreme. I understand that non-ferrous metals fatigue to destruction and that ferrous metals fatigue down to a limit. Titanium's lower elastic module means that for a given deflection, there would be lower stress than on a steel tube in a vibrating chassis. If the tube connection is highly stressed, the steel tube should fail also.

I have never analysed anything like this so I do not have a good gut feeling of what the results should be. I would investigate a failure like that very carefully.

Could the tube bender and work hardening have caused a problem?

--
JHG

 

[moltenmetal]

The area affected was well away from a bend. The material was commercially pure and no hot operations of any kind had taken place where embrittlement might have become a risk. Obviously there was a length between supports in that case which hit a resonant frequency with the vibration of the ship on a long sea journey in that case, which led to the failure. We did thoroughly investigate other joints and found no problems, and the unit has been in service for over a decade without further incident. But you're right- the modulus should help, not hurt in this case.

 

[btrueblood]

Wouldn't a lower modulus lower the fundamental frequency of the tube, making it more likely to be excited by external vibrations? I.e., stiffer is better...ahem.

 

[drawoh]

btrueblood,

Square root of k over m. This would be the same for steel and titanium unless there was something heavy in the tubes.

--
JHG

 

[Comcokid]

Are you sure there was no cadmium in either the swagelok fitting or the tool used to do the flaring operation? In the book Skunk Works by Ben Rich, the head of large titanium bolts on the SR71 were popping off during use. Turned out the wrenches used to tighten the bolts contained some cadmium in the wrench plating. Enough cadmium was transferred to the bolts to cause failure later.

 

[davefitz]

titanium's lower value of E ( Young's mod) affects the deflection ( and fatigue damage) that occurs during flow induced vibrations,and other vibrations. In the heat exchanger business ( such as surface condensers) it is well known that if Ti tubes are used as replacement tubing for other materials, then the support plates need to be spaced much closer to limit the damage caused by hi cycle fatigue.One of the selling points for the alternative low corrosive material ( Sea Cure) is that it has roughly twice the value of E as does Ti, allowing use of widely spaced support plates.

"Whom the gods would destroy, they first make mad "

 

[EdStainless]

Ti fatigue can be odd.
I have seen CP Ti steam condenser tubes fail with longitudinal fatigue cracks.
Not crosswise, not at an angle, but straight longitudinal.
It has to do with variations in properties.

Today about 40% of Ti comes from China, another 40% from Japan and Russia combined (roughly equal), and the remaining 20% is from US, Kazakhstan, Ukraine, and couple of minor players.
You won't find numbers published on the US sponge production. Because there are only two companies to publish it would reveal too much information. But we don know what the total maximum US production could be based on plant design.

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Plymouth Tube

 

[KENAT]

While definitely a niche player, we use titanium in some high frequency flexure designs.

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(probably not aimed specifically at you)
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[cj811]

Edstainless,

On the point regarding the aerospace grade titanium what would be the typical difference between this and non aerospace Grade 5 titanium ? My understand is that the composition of the titanium / properties itself are a characteristic of the grade so Aerospace Gr 5 is the same as Non-aerospace Gr 5. Other than perhaps stronger governance over testing / grain size / No of remelts etc what would be the difference and account for the higher prices ?

Titanium engineer based in China -

http://www.titaniumcn.com

 

[EdStainless]

For the aero grades it is both composition and the melt practice.
These are all vacuum melted, either Ebeam or plasma, usually 2 or 3 times. This processing to get low residuals (and low inclusions) is expensive.
One thing to keep in mind is that costs can be different from what you assume. For Ti 6Al 4V you would think that adding Al and V would be cheap. The Al isn't bad, but the V needs to be pure (no C, no Fe) electrolytic V which is orders of magnitude more expensive than FeV used in steel making.

Some of the poor Gr2 CP out there is so dirty that you can't make premium aero grades using it as feedstock. But it will still make fine heat exchanger tubes.


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Plymouth Tube

 

[Aarne66]

Of course, the military would be prime users.
A sub that can dive below 1,000 meters is valuable:

http://en.wikipedia.org/wiki/Alfa-class_submarine.

Cheers.

 

[MortenA]

off shore in the North Sea its not uncommon to use titanium in the fire water system. There is a Norwegian titanium mafia i think.

 

[EdStainless]

The greatest commercial use for the high performance grades in commercial aerospace.
Long range aircraft are heavy Ti users.
1. Better strength to weight than Al
2. Galvanic compatible with composites

The 787, 777, A380 are huge Ti users (6-4 and 6-2-2 mostly).

I have seen Ti used in armor, large field guns, and some other military stuff.
I saw pieces of the last Alfa class sub, 8"x8"x5" chunks being added to 321 SS here in the US.
The hull was cut up and sold as scrap.

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Plymouth Tube

 

[drawoh]

EdStainless,

I have just designed a titanium preload spring. Titanium has a high yield stress and a fairly low elastic modulus. We have a local machine shop who fabricates the stuff.

--
JHG