Thread: Looking for the best heat treatment for O1

Originally Posted by shooter74743

These are all the same steels right? Is your normalization process just letting air cool? Are you quenching more than once?

The 1,2,4 are the same bar and a third one is just from the same retailer.

During my normalization process I take out and then allowing it to cool slowly in still air as long as it will not be all black(less then 1 min.). I do it three times.

I am quenching only once.

Originally Posted by shooter74743

For us on the silly English system, so I have to do the conversions to F:

Sorry, I will use F next time.

Originally Posted by mikew

We use centigrade in England

Originally Posted by mikew

What hardness are you trying to achieve?

Around 61 HRC. But more important for me the fine and durable edge.

Thank you for your help!

Many thanks for your useful advices. I will utilize them tomorrow.

Originally Posted by PapaTony

Hate to throw something else into this age-old debate, but have you done any cryo treatment on these blades. I've heard differing opinions on O1 needing cryo, but Tim Zowada cryos his blades and his edges are legendary. Of course, Hart cryos theirs too and I'm not very impressed with them, but that's a whole different can of worms.

I plan to use cryo treatment, but first I would like to make a really nice edge on traditional way. I am a perfectionist, I'm only satisfied with the best.

Originally Posted by mikew

Is there any need to normalise if you're not forging? I suppose that comes down to whether your steel is of a known quality?

Maybe not, but I thought it could not hurt.

Originally Posted by Mike Blue

You might try thermal cycling with an oil quench instead of normalizing. You only need to quench to black (400C), not to room temperature and the grain structure will be smaller with each cycle. I will do three cycles routinely. Warm oil would be fine. I suspect with your normalizing process that the grain was much larger than you see in these broken sections.

Today I have made a new small razor for the next attempt. How warm the oil would be?

Originally Posted by Mike Blue

A second variable I would attempt to change given all that has been reported here is to limit the austenitizing soak time to five minutes. O-1 is a simple steel but it does have a minor chromium content and chromium is aggressive in carbide formation. My shop soak times are five minutes.

This will be the next attempt. Thanks!

Originally Posted by Mike Blue

Thanks for the most excellent pictures and good notes on your times and temperatures.
...
Keep up the good work!

Your welcome.

Thank you so much!

Originally Posted by gregg71

... How warm the oil would be?...

Your normalizing process should have refined the grain in your bars/blades. Thermal cycling is basically the same process, as I understand it, but you are quenching into oil from 800C rather than waiting for the blade to cool to room temperature. What you want is the carbon to go into solution at above the critical temperature and back below the critical temperature where it will form grains at a smaller size. Repeating this cycle will reduce the grain structure to finer than you started.

I've done this in all range of oil temperatures. Warmed oil will not help or hurt the cycling process but may have more an influence at the final quench to hardness.

Thanks, I see. And keep it just for a few seconds in the warm oil?

Originally Posted by gregg71

Thanks, I see. And keep it just for a few seconds in the warm oil?

Correct, not long at all.

One more question. And what about the Preheating Temperature: 1110-1290 ° F (600-700 ° C)? I ignored it so far.

Originally Posted by gregg71

One more question. And what about the Preheating Temperature: 1110-1290 ° F (600-700 ° C)? I ignored it so far.

A razor is pretty small compared to some of the industrial sized parts that would take some time to heat into the center of the mass. I don't think you'll need to. I think this situation would be better for someone who owned two ovens because most of them won't ramp up to 800C quickly even if they are already at 600C.