Jump to content
Alveprins

*WIP* Jet Turbine Shaft material Chef's Knife

Recommended Posts

Alright - so this whole thing started in the Metallurgy section of the forum where I test some highly exotic steel from a Jet Turbine Engine shaft... That thread can be found HERE.

As for the continuation of this little project - keep an eye on this thread right here. :)

Alright, so I've tested some steel - and it seemingly has some incredible properties. It hardens to above 60 HRC when quenched in oil - but it stays maleable and not brittle - even at that hardness level. I had to use serious repeated force to break one in half.

Here are some closeup images of the turbine shaft steel itself:

Test 01.jpg

Now - I was lucky with welding the first billet shown below:

Test 02.jpg

However - when attempting to double that - things did not go as well:

Metal Test Progress-3.jpg

Half the billet had a really bad weld going down the middle - it simply would not take. So - I've split them in half to be used later.

Even when twisting the "good" billet - a piece came off. You can see it to the very left in the image.

Metal Test Progress-1.jpg

Some of it WAS usable though - so I proceeded with the build:

Metal Test Progress-2.jpg

Alright - so I put some high carbon steel in the middle as a san-mai lamination between what is now about 70 layers of folded turbine shaft steel, some steel from a couple of fixture pieces for holding turbine exhaust cases in place while machining as well as som 15/20 steel. The san-mai steel is Øberg-steel which hardens to a maximum of 63 HRC.

 

Stay tuned for more progress updates. ;)

  • Like 1

Share this post


Link to post
Share on other sites

Did you test the turbine shaft for edge retention, and how it would temper? Seems like to me chromium, or molybdenum might be an additive in that mystery steel. Could be why it was a booger to weld. But, I am the farthest from a metalurgist as it gets. But still, I am really intrigued by this. I hope Jerrod Miller, or Allan, or Ric, or some other knowlagable fellow might stumble across this. Can't wait to see what you're making :)

  • Like 2

Share this post


Link to post
Share on other sites
12 minutes ago, Zeb Camper said:

Did you test the turbine shaft for edge retention, and how it would temper?

I did not.

I did just quench the knife though... :D at 45 degrees celsius. I did not use this particular alloy for the edge. I used an ordinary high carbon steel for that - so... the shaft steel is a part of the pattern welded steel only:

Metal Test Ground-1.jpg

I did a quick 30sec etch after grinding it to shape. Mind you - this is at #40 grit... :)

The knife is cooking in my kitchen oven right now at 200C, and will continue to do so for a couple of hours.

And then I need to sleep. I've been in the forge for 9 hours today...

  • Like 3

Share this post


Link to post
Share on other sites
Just now, Zeb Camper said:

Quite the pattern you have there!

Nothing out of the ordinary really. Just 70-something layers and a few twists. The bar tor asunder when I twisted it (bad weld) so I ended up using only half of it - with not so many twists. Like, maybe 20 twists, in contrast to 40 which is what I usually do. :)

Share this post


Link to post
Share on other sites

Whatever you did I dig it! Looks almost like granite, or oil sitting on water. You know, natural. I have forge welded before, but only to see if I could. I want to do some pattern welding in the future, but I keep faithful to Aldo's steel, and It seems rare that he ever has anything in stock under a 48" length. So, price is my biggest obstacle. Shouldn't be an excuse with all the scrap A36, and 1018 in the world, but I just haven't tried. Anyway, I won't hijack this thread! Looks good!

  • Like 1

Share this post


Link to post
Share on other sites

UPDATE:

Polished and etched the blade today. I havent cleaned of the oxidation yet - so here's a quick look at what exactly 70 sec. in +12C ferric chloride resulted in:
Metal Test Etched-1.jpg

There were a few misshaps though. A few bad welds, and also a bubble on the other side of he blade.. But - I made the best out of it. Functionally there is nothing wrong with the blade.

Oh, HRC at edge is about 62.

Share this post


Link to post
Share on other sites

Nice work, will be watching this in the hope the misery unravels

  • Like 1

Share this post


Link to post
Share on other sites

UPDATE: Knife is Finished! :D

Blade length: 150mm
Blade width: 34 mm
Blade thickness: 4 - 0,5 mm
Blade hardness: 62 HRC

Handle length: 113 mm
Handle thickness: 15 mm
Handle width: 21 mm

Weight total: 133 gram

Blade material: Jet Turbine shaft steel + mystery-carbon-steel, + 15/20 steel and Øberg-steel for the edge.
Handle material: Borneo Ebony, Camphor wood, buffalo horn, silver tinn, vulcanized fiber.

kokkekniv 001.jpg

Kokkekniv 002.jpg

Any and all critique is as always most welcome. :)

  • Like 1

Share this post


Link to post
Share on other sites

My bet would be that the jet engine material is not even steel, but a nickel base super alloy (or possibly but less likely: cobalt based).  In which case the HT for optimal properties would be quite odd (compared to a standard steel), and the microstructure even more odd.  As a patterning material, as it is here, it would be no problem in a blade, but I would think edge taking and holding would not be so great.  Just a guess though, as I have never really dealt with these applications and materials.  

  • Like 1

Share this post


Link to post
Share on other sites
26 minutes ago, Jerrod Miller said:

My bet would be that the jet engine material is not even steel, but a nickel base super alloy (or possibly but less likely: cobalt based).  In which case the HT for optimal properties would be quite odd (compared to a standard steel), and the microstructure even more odd.  As a patterning material, as it is here, it would be no problem in a blade, but I would think edge taking and holding would not be so great.  Just a guess though, as I have never really dealt with these applications and materials.  

I agree completely... I will most likely use this for pattern welding only - because it makes some insane contrast. Also - it bolsters the hardned edge steel very very well with its super resilliance.

 

I will try the edge retention though... to see whether or not it will hold up.

I have heat treated this like any other steel though. :) It is probably a nickel, titanium-whatever alloy... But at least it forge welds - althought not too good I'm afraid... :P haha!

Share this post


Link to post
Share on other sites
1 hour ago, Jerrod Miller said:

My bet would be that the jet engine material is not even steel, but a nickel base super alloy 

I agree. 

A side note: good check would be to look at the spark pattern. I dissected an in718 airfoil for a project at my last job and made two dive knives from the leftovers. Super tough, very resilient, garbage edge retention. It also barely sparked and the few it gave off were a dull cherry red. 

  • 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...