SOG 1 case hardened ?

[kwackster]

Some time ago i heard the story that the original Seki City SOG 1 was given a special kind of heat treatment.
It was said that the outside of the blade was made quite hard while the inside was kept much softer, mimicking more or less how samurai swords were made.
First question: is this true, and second, is this then the same as case hardening ?
And if so, what is the hardness of the outside versus the inside ?

 

[ashtxsniper]

If the outside was hardened and the inside was soft then it would never hold a decent edge.

 

[Hammer27]

If the outside was hardened and the inside was soft then it would never hold a decent edge.

X2 I think you got it backwards

 

[ashtxsniper]

Theoretically if this is true then every time you sharpened it the edge would get a little bit softer.

 

[kwackster]

I think i have found the source of the story:

http://www.agrussell.com/knives/by_...cialty_knives/sog_20th_anniversary_bowie.html

It must be that the hardening goes a few millimeters deep,

 

[Ravaillac]

I think i have found the source of the story:

http://www.agrussell.com/knives/by_...cialty_knives/sog_20th_anniversary_bowie.html

From the AGRussell description, sounds like differential heat treatment to me, rather then case hardening.

There not too many case hardened knives in those day. Not sure why. Probably it is not effective enough compared to other modern treatments.

The only manufacturers I've heard of using that kind of treatment are some custom maker and a small French manufacturer that has a very limited production.