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 ?

 

[racookpe1978]

An open question, please, on Ti machining and applications:

Ti is justifiably notorious for its difficulty to machine, weld, forge, and assemble, but needed for its resistance to heat (strength at higher temperatures) while being lightweight and relatively corrosion resistant.

With today's 3D modeling techniques - which basically deposits hot liquid "plastic" into 3D shapes using a digitally-controlled and positioned injector aimed at the parts so the incoming material fuses (spray deposits) onto the existing base of the part - why not 3D "assemble" Ti mechanical parts using Ti metal pellets in a vacuum chamber? Thus, rather than "machine off" Ti from a large orginal billet bigger than the final part, you "build up" Ti grains into a very close approximation of the complex final part from "nothing" so very little needs to be machined off?

The Ti pellets or grains (now deposited in the complex shape of what the new part will look like) then can be passed to a "forge" (a die really) and get stamped into their final shape.

Would not the pressure and heat of the forging would sinter the metal powder into an adequate solid for final machining (tapping, drilling, etc) of details while avoiding the complex machining of the entire billet or casting as is needed now?

 

[btrueblood]

Racooke,

The basic form of 3D metal printing is like what you described (using powdered metals not "pellets, though the parts don't get forged but sintered and possibly HIP'd as a final coalescing step. Also, if you spent the money to make a forging die, why bother making a near net shape?

But according to my favorite powder metallurgists Western Sintering, nobody has figured out how to create Ti powders without the oxide coating forming on them, and that oxide can't be reduced by hydrogen-rich sintering atmospheres, so there ain't a good way to make Ti parts from 3D printing at this time.

 

[KENAT]

I think Titanium can already be DMLS though our local shop lists it as 'coming soon' which implies it may be cutting edge stuff as they are no slouches.

I believe it can also be Metal Injection Molded and sintered

https://www.solidconcepts.com/content/pdfs/material-specifications/dmls-titanium-ti-ti64.pdf

However, still $ with some limitations.

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[drawoh]

racookpe1978,

I need a small number of pieces. Titanium is machinable enough. The thing has to work.

Apparently, people are using ABS FDM models as patterns for investment casting. This would be really cool if it were not for titanium's high melting temperature. I have no need for this quality, but it still is what the material does.

How feasible is sintering, given titanium's melting point, and the high yield strength of the alloy I want?

--
JHG

 

[ornerynorsk]

The use of ABS FDM parts as a shell pattern for investment casting is debatable. When the concept first arose, our investment casting house played around with it, but found that far too much ash remained in the shell after burnout to be practical. The FDM wax machines do a much better job of it.

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.

 

[EdStainless]

1. In the world of engineering alloys Ti (the high strength versions) have poor strength vs temperature properties. Along with drop in strength come a serious drop in modulus and permanent changes in properties.

2. Considering the very limited fatigue resistance of Ti to start with I don't want to near any Ti part that sees cyclic loading if it started as powder and didn't get HIPed. Along with 100% volumetric X-ray examination.

The best Ti parts made by any additive process have been Ebeam fused powder. The defects in them are still very large and preclude all but light load static applications.
We have looked into some these process to 'repair' forgings or extrusions, so far no-go.

ornerynorsk is on the mark, the ABS FDM works great for steels, but not well for SS, Ni alloys and Ti.

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[btrueblood]

Kenat,

My source says Ti powder can be sintered & HIP'd, but what results is a product with lot of intermetallic oxides, so the material has low ductility, much lower than conventionally produced alloys. Or, in other words, what Ed said.

 

[KENAT]

btrue - I believe you, it's been a while since our guys were out and I could have sworn they talked about doing Ti etc. but I forget details.

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[KENAT]

http://www.defense-aerospace.com/ar...mos-3d-printed-propulsion-for-satellites.html

Printed Titanium rocket parts apparently.

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[EdStainless]

There have been a lot of AM Ti parts, but none that are dynamically loaded.

None of the 3d AM process for metals have shown a capability to make parts that are free from significant defects.
Right now people get around this by over-design. Eventually they will get there, but it will take a while.

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[tbuelna]

A bit late to the discussion, but I just came across the topic. When it comes to commercial use of any raw material, including metals like titanium, what matters most is the cost/benefit relationship provided by the material for the given application. Titanium alloys are presently still too costly for many commercial applications. At one time in the not-too-distant past, aluminum was also far too costly for most commercial applications. But improved production technologies over the past few decades quickly reduced the cost of aluminum to the point where it is now economical to make beer cans from it.

The same situation will happen with titanium when lower cost technologies are developed for producing it. Just like aluminum, there is no shortage of the raw material resources needed to produce the metal.

 

[cj811]

one of the problems we have with the powder is while we manufacture it it is very messy to handle and cant be couriered for people to play around with etc (not that alot of people have sintering machine lying around..). I think distribution and handling is a real challenge for Ti in AM in the short term.

Shaanxi North Steel Co.

 

[tbuelna]

AM using Ti powder is a whole different can of worms. The AM process requires very pure Ti powder and an inert atmosphere to laser sinter the material. The melting point of Ti is quite high so it requires a very high powered laser to fuse the Ti powder layers properly. There is also the problem of the reduced fatigue properties resulting from the laser sintered Ti materials.