Jump to content
Alveprins

Exotic material test - Jet Turbine Steel

Recommended Posts

Ok, so I've got some quite exotic steel that I've been testing out today... All I can say is that I do not know the composition, but I do know that it is from a modern Jet Turbine engine shaft used in commercial aircraft.

Now - I wanted to see if it would take a quench- so I tried.

Quenched it above critical in food oil. I did not heat the oil - and it was probably around 15 degrees celcius.
I tried a file on it - and it would not bite. So - I put it in a vice and banged it with a hammer in hopes to break it and see the grain structure. Nothing. It just bent - slightly. So I banged and banged the steel piece until it had completely bent over. Then I banged it back again, and back, and back again until it finally broke out of structural integrity fatigue.

I measured the hardness of the hardened piece with Japanese hardness tester files. The 60HRC file did not bite - but the 65 HRC file scratched it somewhat.

Here are some closeup images of the break:

Test 01.jpg

I was amazed that even over 60 HRC it would not break - even with no annealing or anything. I simply quenched it in oil, waited for a little while - then cooled it down in room temperature water. And still it would not break.

Oh - and I made a pattern welding billet from this mystery-steel, combined with regular high carbon steel:

Test 02.jpg

This is how clear the pattern is even without acid or anything. Just simply cutting off a piece with my angle grinder - and it looks like this.

Oh - and speaking of angle grinder.. This steel EATS cutting discs like it was candy. I kid you not. The metal is hard to forge - even at almost white hot. Even at welding temperature it moves slowly under the hammer - and leaves almost no scale. Very very strange behaviour. It is almost as if it is both hard and non-brittle at the same time... Incredible stuff.

 

Any thoughts from you guys? :)

Share this post


Link to post
Share on other sites

What shaft in particular?  I would have thought it was either a titanium-nickel or stainless alloy, but neither of those would have forge wleded so easily.

Edited by Brian Dougherty

Share this post


Link to post
Share on other sites
4 minutes ago, Brian Dougherty said:

What shaft in particular?  I would have thought it was either a titanium-nickel or stainless alloy, but neither of those would have forge wleded so easily.

I can't disclose that. Sorry. :D

Share this post


Link to post
Share on other sites

i am following this. can't wait to see a blade forged out of this!

Edited by Joël Mercier
  • Like 1

Share this post


Link to post
Share on other sites

UPDATE: Alright - for those who want to follow the knife build itself - I kindly referr you to the WIP thread in the Show and Tell section of the forum.

Link to thread HERE.

Share this post


Link to post
Share on other sites

Not a lot of parts in aircraft are made of steel. I've rarely had to design anything in steel, and I never worked on engine parts, so I can't help there very much in determining what type of steel it might be. However most steel or other alloys can be found either in MIL-HDBK-5 (outdated) or MMPDS (newer). MMPDS you probably won't easily find online except as expensive download, but MIL-HDBK-5 is easier to find (f.e. here: http://www.barringer1.com/mil_files/MIL-HDBK-5.pdf). It doesn't list hardness, but yield strength can be used as indication, and there are conversion tables online which allow you to see the relation between yield strength and hardness. I don't know of any steel that would have the kind of properties as you describe, with a very high hardness or yield strength, combined with a high ductility. In general the rule is, the harder the steel you choose in a design, the more brittle it will be, as you'd expect. It sounds more like it may be case hardened? So it's got a outer layer that is hardened, but inside still soft and mallable?  I do vaguely remember from materials classes that that was done for shafts in particular, but I could be wrong (it's been 2 decades). 

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...