Experience of a more accurate O1 heat-treat?

[daizee]

Hi Heaters and Treaters,

As is evident from an earlier thread, I'm interested in understanding and evaluating my current O1 heat-treat process. Several times experienced makers have said that shade-tree O1 can be quite good, but treating to the potential of the steel will really knock your socks off.

I'd like to know what it feels like to have my socks knocked off without testing a blade to destruction.
Hopefully there are some detectable properties that don't spark a religious war...

Assuming identical profiles, grinds, and edge geometry, what differences should I look for with knife-in-hand that would allow me to detect differences in a useful way? How do YOU know that you've really nailed it?

My understanding is that a proper soak, for instance, will fully diffuse the alloying elements, allowing a finer grain structure to be created during quench, resulting in greater hardness prior to temper. Assuming equal tempering cycles, how might I detect that difference while finishing and using the blade short of snapping it and looking? (I wouldn't know what or how to look anyway). What else should I look or feel for?

I'm looking for thinks like "the edge feels like X vs. Y when doing Z", or "a such-and-such cutting test shows this on my own blades", rather than "the knife just feels better".

I was mulling over scrounging a hardness tester, but I'm more curious about in-use differences.

Thanks,

-Daizee

 

[sunshadow]

My experience was that the blades didn't break even under extreme abuse, the edges didn't chip or roll, and the blades were able to take and keep a finer (read sharper) edge.

-Page

 

[butcher_block]

also jsut cause you get more harness from proper heat and quench doesnt mean that you should keep all that extra hardness post temper
you should still temper to the finish hardness you are after. you might fine tho in testing that you can now run a point or 2 harder then you are use to while still haveing toughness you ae after

 

[parbajtor]

Cutting testing using a range of bushcraft chores and then back to paper slicing should show a difference in performance.
With plenty of experience, you can fairly accurately assess the hardness during sharpening.
Brass rod test.

 

[Rick Marchand]

My understanding is that a proper soak, for instance, will fully diffuse the alloying elements, allowing a finer grain structure to be created during quench, resulting in greater hardness prior to temper.

I don't believe that the soak refines the grain. The grain size was determined by everything you did PRIOR to the final quench. As long as you don't overheat during the final quench, your grain size will be exactly as you left it. The soak allows carbon and alloying to properly diffuse and distribute throughout the grain matrix. That way all the "stuff" that induces hardness, corrosion resistance, etc... gets spread out evenly. I hope I got that right.... I know the concept but sometimes the terminology eludes me.

You probably won't notice the effects, off-hand(aside from a couple HRC points, perhaps).... but in time they WILL be apparent in performance and maintenance.

 

[Darrin Sanders]

If you actually wanna break a blade and not lose it do this. Make it a couple of inches longer than you want, H/T it and break the first 2 inches off, then reprofile the tip and finish grind it and go from there.

 

[Patrickknives]

I keep a few cutoffs from the same bar and put them though the heat treat process along with the blade. I also will experiment with some tempertures to see if there is much difference. There are two things I notice when you get the HT just right if you have been off a bit, first you will wonder why the blade is so hard to finish grind, typically you will need to switch to fresh belts. the other is if you do the cuttoffs and put them in the vise and try to bend, you will have the beat the _______________ out of them to bread or bend. You can also put an edge on a scrap and try some cutting. You dont need big pieces