Cryo hardening effect on old blades?

[kbright]

I was asked to fix an old Sabatier 10 inch chef's knife with a broken tip. Don't know much about the blade, but it is stainless and maybe 50 years old. Maybe a K-Sabatier product.

So I fixed the tip, but then went crazy and did a regrind, lowered the tip, took out the bolster, did distal taper and a flat grind close to zero degrees. Changing the handle to Wa style. I'm calling this a SabaGyuto. Current dimensions are 235 x 45mm with spine width about 3mm above the choil.

Anyway, I believe these old blades were maybe RC55 hardness. Would cryo treatment raise the hardness much on this 50 year old stainless blade?

 

[DevinT]

Retained austenite is what converts to fresh martensite during cryo quench. Retained austenite becomes stable over time so it is unlikely to increase the hardness of this one. Some high speed steels can convert RA with a cryo quench even after significant time has passed. Maybe if the stainless is alloyed with moly, you might gain a point.

Hoss

 

[kbright]

Yeah, Thanks. I was not optimistic but thought I would ask. One additional point hardness isn't worthwhile, I was hoping to get up to 59 or 60.
But this is an experiment to make an older knife useful again. Anyway, it will be easy to sharpen.

 

[scott kozub]

That new profile looks so much better. Man I hate those bolsters that go down to the edge.

The old handle had some big pins but the holes in the tang are small? How was the old knife pinned?

 

[kbright]

That new profile looks so much better. Man I hate those bolsters that go down to the edge.

The old handle had some big pins but the holes in the tang are small? How was the old knife pinned?

The old Sabatier scales were held on with rivets. I used the platen corner of my belt grinder to grind off the heads, and the scales came off.
I was really surprised how much rust and uneven rough surface was under the scales.