How to confirm a material that has no documents when you buy it?

T

tarmo120

Active User
Registered
Hey there.
I'd like to ask some info from you guys.
A few days ago I bought a titanium bar, or so I was told.
The bar is 31mm in diameter and 347mm in length. This bar weighs 1085 grams.
It feels pretty light compared to some other similar size materials.
But when I tried to turn it in the lathe(fairly small chinese lathe), it turned almost as easily as aluminium.

So this brings me to the question. How can I determine whether it is or is not titanium.
For the record I was told it is a grade B titanium.
Here are a few pictures.(Hope they show up)

20130312_150349.jpg20130312_150405.jpg20130312_150422.jpg20130312_150540.jpg20130312_150553.jpg20130312_150616.jpg

20130312_150349.jpg 20130312_150405.jpg 20130312_150422.jpg 20130312_150540.jpg 20130312_150553.jpg 20130312_150616.jpg
 
Grind a area with a bench grinder or even a stone in a dremel type tool. Titanium will give off a shower of brilliant white sparks.
 
Aluminum has a density of approximately 2.70 grams/cc and Titanium has a density of 4.50 grams/cc. Your posted dimensions yield a density of about 4.15 grams/cc so it would appear to be Titanium.

FWIW I had some pieces of Titanium and I faced one off for fun. I thought that it machined fairly easily, but I did notice that it made much more heat than aluminum (really hot chips). It did turn out nice spirals like a piece of aluminum, but I thought they looked a bit more tinged whereas the aluminum chips stay pretty much the same color as the original aluminum material.
 
Ti melts at 1600+ C and AL melts at 600+ C. Put some of that swarf over a flame. AL will wilt and droop immediately.
 
I've come to the conclusion that this material is definitely not aluminium, and I would think that a same size stainless bar would be heavier.
So I will test it on the grinder next time I get the chance.
Thanks for the info.
 
The spark test will tell you very quickly. Aluminum doesn't spark and 300 series stainless sparks are straw colored.
 
I make things out of Ti more often than anything else. Looks like Ti to me & not Al. Al is very soft compared to Ti, you should be able to tell easily in that sense. Like Ray mentioned, take some of the swarf (finer the better), bunch it up & light it with a lighter, if it's Ti it will burn bright & white.

You can also try drilling it, you will be able to tell real quick if it's not Al.

You can also try anodizing it. Get some soda or soap solution, hang a piece with some welding wire (best to hang it with a piece of Ti or nobium wire but for a quick test it's not needed), stick a cathode in the solution making sure it doesn't come in contact with the anode or Ti, apply at least 10v to the cathode & anode & it should turn a gold bronze color. 20ish volts well get you purples & blues. Two 9V batteries in series will do the trick. If you really want to anodize some piece the right way, let me know & I can help you with setting up the proper set up.

Don't know what grade B Ti is though. Ti is graded by numbers. Grade 5 is the most common alloy which is 6Al4V. Grade 2 is generally the most common grade of unalloyed Ti, aka CP (commercially pure). Obviously grade 2 is softer than grade 5. I suspect you might have grade 2 rather than grade 5.
 
Take it to your local scrap yard. They have one of those $5,000 lazer guns. They will shoot it for you and tell you what it is if you ask nice!
 
You must log in or register to reply here.
Back
Top