hardness, temper and temper line

[arty]

Hi kamis use a very different method to zone harden the edges - at least it is different than the methods used by Japanese swordsmiths. The FAQ indicates hardness of RC 60 at the edge. The temper line on my GRS appears to be close to the edge - perhaps 5/16 from it near the tip of the blade. A line appeared after I polished out some corosion at the end of the blade (with 2000 grit abrasive paper), and I assume that it is a temper line. Am I correct in this?

How far back from the edge is the steel at full hardness and how hard is the "softer" steel at the back/spine? I realize that the blades are made by hand, and so there is no sure way to tell hardness without testing. I wondered whether the change in hardness is gradual or sudden. I am asking about this, because I didn't see a discussion of this at the Hi website. I know that the Kamis use a distinctive method ... involving pouring water to cool the blade's edge.

I would appreciate any info.

 

[ddean]

That's probably it.

Search this forum for the keyword: hamon

That should get you several threads on revealing it
by etching.

The pattern varies a lot,
but it usually isn't -very- deep.

The frosty zone is intermediate hardness.

I think the spine is usually around 45 compared to the
edge of 60 or so.

 

[Mark Nelson]

More then likely that is in fact the temper line. most of the Khurks's tips are not hardened. This is so that there is less chance that the tip will break off. For the most part that area isn't going to get alot of abuse. Here is a pic of my 12" Ak as you can see the tips is not hardened at all (the very dark area along the edge is the hardened part).