Titanium

Discussion in 'Sheet Metal' started by cheapracer, Nov 7, 2019.

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  1. Nov 7, 2019 #1

    cheapracer

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    Does anyone here know much about Titanium?

    There is quite a bit for sale around where I am, Grade 2 mostly as far as I can tell, but higher as well.

    I realise the grade is low means it's lower quality, but what should I know further? Is it still as strong as steel at half the weight etc?

    Is there a grade I should be aiming at for 'general aircraft use' (relative), like you would generally use 4130 if steel, or 6061/2024 if aluminium?

    Not much discussion about it, are there drawback or just too expensive for general use that scares people off?
     
  2. Nov 7, 2019 #2

    Riggerrob

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    Titanium is most valuable in hot areas. That is why some builders like to install titanium firewalls behind their engines.
    Titanium rods also have special flexibility, which is why a few kit factories offer them as Wittman-style spring landing gear legs.
     
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  3. Nov 7, 2019 #3

    cheapracer

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    Thanks, sounds like one use for it, I'll look into the heat part as I was going to use stainless, and it's a big piece heavy of course.
     
  4. Nov 7, 2019 #4

    BBerson

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    I got some titanium rods at the scrap yard. My lathe couldn't machine it. Too hard.
     
  5. Nov 7, 2019 #5

    Angusnofangus

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    I haven't worked with titanium for awhile, but IIRC, the stuff we were using was Grade 5 (https://continentalsteel.com/titanium/grades/), and it was just used for firewalls. Sometimes those firewalls doubled as aircraft skin. Case in point, Sikorsky S-61's, the fuselage skin under the engines is also a firewall, therefore it is titanium. Aluminum is much easier to work with, besides being a lot cheaper. Personally, I don't see much much of a case for using titanium, except for firewalls.
     
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  6. Nov 7, 2019 #6

    cheapracer

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    Thanks, I would only be laser cutting and folding 1/8" sheet I think.

    I guess I should ask then: Does it fold ok? Yes I can look on the net, but often first hand experience differs from theory, as many of us well know.
     
  7. Nov 7, 2019 #7

    Angusnofangus

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    The stuff I've worked with had a lot of springback when bending, Folding over .125 sheet would have been impossible with that alloy. Don't know about softer stuff.
     
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  8. Nov 7, 2019 #8

    cheapracer

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    center wing spars, fuse corner load plates, seatbelt mounts, landing gear mounts, rudder quadrant

    There's a few possibilties, but yes, comes down to economics as well. Just thought i would ask before I went looking the next few days, thanks for replying.
     
  9. Nov 7, 2019 #9

    Dana

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    Grade 2 titanium isn't "lower quality"; it's commercially pure titanium, as opposed to grade 5 which is a titanium-aluminum-vanadium and higher strength.

    Very roughly, titanium has mechanical and thermal properties comparable to stainless steel at 2/3 the weight. But the elastic modulus is lower, closer to that of aluminum, at twice the weight of aluminum. Bike makers like it for its "springiness" compared to a similar strength steel or aluminum frame. It's a ***** to machine, and requires special techniques to weld.
     
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  10. Nov 7, 2019 #10

    cheapracer

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    Thanks Dana. Yeah I knew about the welding problems.

    It maybe twice the weight of aluminium, but, like steel, you need to use less of it. Ends up somewhere near the same weight for a large increase in strength over aluminium, happy to be corrected, here to learn ...

    There's really big differences between the grades ..

    Ti.jpg
     
  11. Nov 7, 2019 #11

    pictsidhe

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    It's a royal PITA to work with. I suggest you buy a few bits and play with them.
     
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  12. Nov 7, 2019 #12

    BBerson

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    If the elastic modulus is similar to aluminum, as Dana said, then your beam caps will need about the same thickness for buckling in compression. Could be heavier.
     
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  13. Nov 7, 2019 #13

    pilot103

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    Titanium isn't harder to work with just different. I spent 35 years certified to weld everything from A ( aluminum)to Z (zirconium). It was by far my favorite thing to weld. I have machined it and prefer it to stainless. IT is also very expensive.
     
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  14. Nov 7, 2019 #14

    cheapracer

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  15. Nov 7, 2019 #15

    Toobuilder

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    I have access to scrap from my employers and it's almost exclusively 6AL-4V. It's incredibly difficult to bend and takes special care to prevent cracks. I made a "L" angle out of paper thin .016 Ti and it took a LOT of force on the brake to bend even a 30 inch section.

    Can be drilled and machined in a home shop with sharp tools and technique.

    It's magic stuff though.
     
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  16. Nov 7, 2019 #16

    cheapracer

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    Yeah, looking on the net doesn't give me much hope of bending 1/8" successfullly, most suggest heating to do it.

    Anyway, was just a thought experiment, a rough estimate looks like a 4' x 8' x 1/8" sheet might cost the same as 25 sheets of 0.020" did ...
     
  17. Nov 7, 2019 #17

    Doggzilla

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    Go check out how bicycle builders work with it. Incredibly difficult to properly bend or mold.

    For complex shapes they cut and weld instead of bend. That’s why you almost never see anything but straight tubes and beams with welds all over the place.

    If you bend it you have to repeatedly heat treat it after minor bends, which is a royal PIA.
     
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  18. Nov 8, 2019 #18

    Jimstix

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    Must be sawn very slowly to avoid work-hardening.
     
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