question about quenching swords

cbr900son

cbr900son

Joined
Mar 3, 2011
Messages
1,010
Ive been looking at alot of japanese sword making videos and threads and keep seeing something about the curve coming from quenching? Is that true? IS it something with forging or do the stock removal guys deal with it too? Just curious
 
If you are quenching in water, the curve will come naturally. I understand that the really good quenching oils limit deformation, but all oils will make the blade curve in the wrong direction (toward the edge), so you have to forge the curve in. Stock-removal sword makers either need to make the curve themselves or grind a straight blade and quench in water.

- Chris
 
It's called a Sori

It results from the differences in steel structure when doing a clay backed differential heat treat.
 
Didnt know the clay baked thing could do that much for the curve. Is that the part where they make the hamon or is it something else they do?
 
I've had quite a few blades have negative sori when quenched in oil, with no clay involved, or edge quench. I did not think a differential quench (be it clay or an edge quench) was needed for a blade to develop sori?
 
There are smarter people here that I to answer that.
I was aiming for the quick generality.

I believe that the difference in thickness between spine and edge on a shallow hardening low alloy steel
has the same effect.

The thicker spine quenches slower than the thinner edge and gives essentially the same result.
 
I have been reading up quite a bit lately on this because I am wanting to attempt an aikuchi soon. One way I have seen people prevent the negative curve with oil is to quench spine first. Water quenching can be scary with a high failure rate, but those who have quenched spine first in oil say this solves the problem. I don't know first hand though.


-Xander
 
Steels differ in their response to quenching, this is where you need to do your homework.
 
Ed is right, the steel has to match the quench medium, which inturn has to be compatible with the desired results. I had a vertical quenchtank with a fast oil that was great for knives but as I got into longer pieces the negative sori reared it's ugly head. I switched to a horizontal tank and quenched spine first to resolve the problem. My Houghton Quench K is as fast as Parks 50 and I have no problem getting a sori with a clay-backed blade.
 
You must log in or register to reply here.
Back
Top