WIP discontinued after HT

[Karim 62]

Just wanted to share my mistake in HT this blade.

 

Frustration got the best of me after careful preparation and 2 times oli quench still not a hard edge.

So threatened the blade whit water and yes the edge listened ... slowly realizing differential edge HT whit water and then oli could have worked out.

 

Please feel free to comment, still learning

 

I liked this one

 

preparation

 

 

Check out the cracks!

[Dan Bourlotos 26]

It is interesting that it cracked the way it did and I think it might tell you something about what happened. I think you are right in that the edge cooled too quickly for the spine, but there is another way to look at it: The spine cooled too slowly for the edge. Usually when I differentially harden I use (what looks to be) a thinner layer of clay on the spine and I leave the actual spine uncovered. I had cracks out the yin-yang until I started doing that. Its just an observation.

Also, what alloy?

[Austin_Lyles 187]

A real bummer. Oddly though, that cracked backwards???... In my experience, when quenching like you did, if the blade cracked, it would be along the hardened edge as positive sori took place. The edge couldn't take the strain of stretching and gave away.

 

A few things. Dan brings up a good point, thinner is better with clay. Yours is on very thick. Also, like Dan, I'd like to know the alloy of steel? It sounds like you may be using a "mystery" steel which will cause problems like this.

[Karim 62]

nothings seems as it is The steels are mostly recycled:

-Old file damask for the edge (till where it cracked)

-Spingsteel alloy that is super tough

 

My assumption was that the file damask would harden in oli, dont know why it didnt

[Theodore An. 20]

overheated??

[jake cleland 719]

High alloy, deep hardening spine and low alloy, shallow hardening edge is just asking for trouble, I'm afraid. If you have spring steel anywhere in the mix, water is not your friend If it doesn't harden in oil, bump up the temp 25f and try again. Remember to file through any surface decarb when checking for hardness. Have you checked if the edge hardened on this attempt? If not, your files were probably case hardened.

[Karim 62]

Yes the edge listened, knowing this i agree this combination is asking for troubles

[Ryan Merton 0]

Still looks pretty sweet.

[Gary Mulkey 1,445]

This one is a little odd in that it cracked at the spine and not at the edge. I'm would also guess that it was over heated. Also, judging by your photo, you used too much clay (satanite) on it.

 

Remember for a good hamon, low temp---thin clay. I usually H/T @ 1440 with approximately 1/16" of satanite.

 

Gary

[Joshua States 2,500]

I have a theory......more like an hypothesis really, about why the blade cracked where it did.

The clay acts as a thermal insulator. This not only keeps the blade from getting hot enough to harden, but it also keeps it from cooling as rapidly as the areas with no clay. So what happened, is the edge got up to temp while the spine area lagged far behind (clay too thick). When the quench occurred, the edge cooled rapidly and contracted while the spine did not. This contraction pulled the edge in lengthwise which would pull the spine out longer. If the spine is not hot enough to stretch a little with the edge contraction, it breaks.