mystery metal ID

Evening all, I have been sent a piece of 'mystery metal' to make some heli parts from. The sender told me its 6Al4V Ti, which by all accounts is a PIG to
work with. However it isnt... which leads me to suspect its not Ti but a 7000 series Alloy. Its about the same density as ally, just by hand comparisons, and its not magnetic. about the only simple test I can think of is to just melt an offcut (Ive already made some parts). If I can melt it before it gets red its ally of some sort, if not it might be Ti, and people are 'bigging up' how hard it is to machine.... any other simple tests anyone can think of or comments?
cheers
Dave
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If the density is about 2.8 g/cm^3 it's aluminium and 4.5 it's titanium. Easy enough to check.
--
Dave Baker



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If you can set fire to it, it isn't ally but it could be Ti (or Magnesium). But do it outside & don't try to burn it all at once...Ti fires are just a little bit more exciting than you need in your workshop.
Regards, Tony
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I have some small swarf. Ill try burning that. the density one is possible if I had an accurate enough scale, the alloy prototypes weigh under 0.4g...
Dave
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writes

Yes, but which Ti alloy? There are hundreds. Without some testing gear (UTS, young's modulus, or chemical analysis) you will not find it easy to tell. 6-4 Ti is not that hard to machine provided your tool is dead sharp. Once the tool goes slightly blunt it will go to hell very quickly. Nothing like Al (or any Al alloy I've come across) though.
BTW, to distinguish Ti from Al, all the 6-4 Ti I have (it's all sheet material) is noticeably yellow and dull compared with Al. Put the two side by side and it's easy to see the difference.
David
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David Littlewood

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An afterthought: Take a piece of EN1A and try scratching the metal. The pieces of Al alloy I tried it on scratched easily; the 6-4 Ti showed some superficial marking of the surface oxide layer, but no scratching. No need to make the EN1A into a point - the sharp edge of a turned bar offcut is sufficient.
David
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David Littlewood

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.
As it happens the actual alloy is unimportant for this application, all the Ti's have better UTS than alloy as far as I can tell. The part is marginal because its a stupid design, not because its alloy. I thought Ti would be cool to make them from, and was sent this piece of metal to try.
Dave
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dave sanderson wrote:

Whack an edge against a grinder wheel, and watch for the bright white sparks of Ti. Or not.
Ti. is not too tough to machine, unless the tool rubs, then it's a mother#$%^&**$ !! Usually, if you hear a tool squeak, it's too late already. :-)
Cheers Trev
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Now that sounds like a good 2 second test :)
Dave
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wrote:

Its not Ti, or any other metal which sparks. no sparks at all, got to be alloy of some type. Thanks all
Dave
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dave sanderson wrote:

Standard one in our shop.
The sparks from Ti. are pretty bright.
And there's almost always a grinder about the place...
Cheers Trev
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wrote:

Yep - I was trying to drill a 1mm hole in a piece of Ti sheet the other day. Combination of way too slow a speed and a slightly dull drill - just didn't even scratch the surface.
Regards, Tony
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Tony Jeffree wrote:

We go through a lot of $30 or so per piece, solid carbide drill bits, drilling Ti. fasteners out, when they have galled into the Ti. nut, or have beem stripped.
Seems expensive, until you shop the price of replacement parts that can't be got anywhere at all.
Gotta be deadly sharp, gotta keep the pressure firm, steady, and straight, and the rpm's can run anywhere from slow to medium, relative to the drill size.
A guy with a shaky hand, or with too much caution in him, will destroy a LOT of carbide drill bits in a day.
Cheers Trevor Jones
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