Thread: Looking for the best heat treatment for O1

I'm not the expert that Mike is, but I have produced a bunch of great edges so please take this for what it's worth. My setup is just a forge with a pyrometer. I can play with the valves and control temperature pretty well. I quench in a medium oil I got from Mcmaster Carr which I keep around room temperature (85 F usually, I'll heat up a piece of steel and drop it in if it's cold outside).

I've tried a lot of different HT methods, but found that Kevin Cashen's worked the best for me. http://www.cashenblades.com/steel/o1.html

To boil it down to what it means for you, here's what I'm seeing:

1. I think you're normalizing too low (1500 F instead of 1600 F).
2. I think you should stress relieve at 1250 F and ramp to 1500 F before quenching.
3. I think your oil is too hot. From what I understand, o1 doesn't want a super fast quench. Many people recommend Park's AAA quench oil, which is a slower oil than Park's 50. Not sure how it compares to what you're using. If we look back at Mike's previous comments, the hotter the oil, the faster the quench.
4. I think you should temper a bit hotter. Perhaps this is a personal preference, but I like my blades between 60 and 61 HRC; I just think that more than that is a pain to hone and feels too rigid on my face. This shouldn't really affect grain size, but should play into the edge you end up getting out of it.

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.

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?

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?

In this case, clearly yes. The steel mills produce bars. They don't necessarily control the temperatures to do so. There are several of us who have been fooled by materials we purchased from mills in quantity. It always requires test batches to make sure it performs the same as we expect.

Over time, the experienced smiths seem to have developed a cynical skin about this. Sometimes they send you something that is "close enough" but not what you really wanted. Sometimes the yard monkeys are color blind and send you the wrong color coded material.

Papa, the subject of cryotreatment is interesting.

I don't think this problem will require it. It adds a set of variables that will only distract from the set of tools Gregg has to work with now. I don't believe it will change the grain structure in a good way since most of the work there is done before the final quench.

I have done it, and don't believe it to be useful or economically practical IF the steel is heat treated correctly AND is a low alloy steel like O1. High alloy steels (stain resistant etc.) can be improved after quenching. YMMV.

Update: I read the Uddeholm link that Mikew provided. It contains cold treatment information my old sheets do not. They include a data line labelled retained austenite, and that is the structure than cold treatments attempt to correct. That Uddeholm includes it is enough for me to acknowledge I don't know everything especially when trying to keep up to date on so many things at once. Uddeholm suggests such treatment for dimensional stability and structural components. I don't know how that will translate to razors but eventually one of us will figure it out.

Caveat: To this date, none of the O1 razors I've heat treated have returned for problems, or I have not been made aware of feedback I would like to have.

Originally Posted by Mike Blue

Papa, the subject of cryotreatment is interesting.

I don't think this problem will require it. It adds a set of variables that will only distract from the set of tools Gregg has to work with now. I don't believe it will change the grain structure in a good way since most of the work there is done before the final quench.

I have done it, and don't believe it to be useful or economically practical IF the steel is heat treated correctly AND is a low alloy steel like O1. High alloy steels (stain resistant etc.) can be improved after quenching. YMMV.

Update: I read the Uddeholm link that Mikew provided. It contains cold treatment information my old sheets do not. They include a data line labelled retained austenite, and that is the structure than cold treatments attempt to correct. That Uddeholm includes it is enough for me to acknowledge I don't know everything especially when trying to keep up to date on so many things at once. Uddeholm suggests such treatment for dimensional stability and structural components. I don't know how that will translate to razors but eventually one of us will figure it out.

Caveat: To this date, none of the O1 razors I've heat treated have returned for problems, or I have not been made aware of feedback I would like to have.

I appreciate your input as always Mike

I'd like to highlight some of the things you said that stand out to me.

1. Quality (or state) of the steel is questionable. If he's just doing stock removal, the grain size wouldn't be explained.
2. Thermal cycling. Why didn't any of us think of that? I've done this with different steels, but not O1. This could be great!

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.

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.