Question for Kevin, a comment you made. . .

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Fox

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Feb 6, 2000
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Kevin, in Chiro's thread about O1, you said:

"I have been working O1 for a few years myself, and if you have the ability to hold below 1500F. for extended soaks, the benefits are very remarkable. There are tons of carbides that we cannot take advantage of until that is done. HRC goes to maximum and tempering takes a bit more effort but is well worth it."

Can you discuss this a bit more? What are the benefits? What temperatures and times? In reading some manufacturing specifications, notably Crucible's, they have a foot note that indicates using the lower austenitizing temperatures (in their case, 1450 - 1500F) decreases HRC, but increases toughness. Your comment indicates a different result, but there may be other factors not discussed in Crucible's instructions. I use a lot of O1 and am always trying to improve the qualities of my heat treatment. I can do extended soaks and would like to play with this and make some coupons for Rc testing. It would be nice to have a starting point.
 
Fox how would you perform these extended soaks? I wonder if he is talking about bringing the O1 up to the forging temps slowly and then aus-forging or if hes got a HT protocol thats unconventional. Its cool to think about a steel thats very forgiving to the inexperinced heat treater, but has alot of room to improve and experiment. I would like to specialize in O1 when I start forging so this could be a very exciting development showing alot of questions and suggestings for experimentation.
 
ssunfish said:
Fox how would you perform these extended soaks? I wonder if he is talking about bringing the O1 up to the forging temps slowly and then aus-forging or if hes got a HT protocol thats unconventional. Its cool to think about a steel thats very forgiving to the inexperinced heat treater, but has alot of room to improve and experiment. I would like to specialize in O1 when I start forging so this could be a very exciting development showing alot of questions and suggestings for experimentation.
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Sunfish, you need a good furnace or salts with digital controls so that you can hold your austenitizing temperature at a specific point for an extended period before the quench. The questions are: what temperature and what period?
 
I am wanting to hear the answer also. My guess would be he does an extended soak below the 1500° to make sure all the "stuff" in the steel is in solution and then bumps to a higher austenizing temp before quench. That way he avoid grain growth that occurs when you are much above critical.

AC1 is around 1370° based on the info I have so you could do a soak at 1400° and not grow much grain but still get the carbon into solution. Then bump upto your prefered austenizing temp and then quench in your salts to just above Ms, check/fix for warps, and then let her transform to martensite.
 
Laredo, that is my thinking as well. I am curious as to how low one can go with O1 and still get optimum conversion. I believe I read something recently where mete said 1450 and ten minutes gives excellent results. I wonder if Kevin is going lower than that?
 
Fox, I am anxiously waiting for Kevin's response. The only time I have used O1 is for a prototype balisong. I have more O1 that I want to use so it will be very interesting to hear what Kevin has to say. One thing for sure is that he loves his O1 and L6 and has done extensive testing on it. I have the high temp salts but I wish I had the low temp salts too.
 
I'm not Kevin, but I once stayed at a Holiday Inn :)

I didn't play him on TV either.

I austenitize O1 at 1450-1475 for 10 minutes in my salt bath and quench in 129F AAA. :)

-Nick-
 
Fox said:
Kevin, in Chiro's thread about O1, you said:

"I have been working O1 for a few years myself, and if you have the ability to hold below 1500F. for extended soaks, the benefits are very remarkable. There are tons of carbides that we cannot take advantage of until that is done. HRC goes to maximum and tempering takes a bit more effort but is well worth it."

Can you discuss this a bit more? What are the benefits? What temperatures and times? In reading some manufacturing specifications,...
Click to expand...

well- "There are tons of carbides that we cannot take advantage of until that is done. HRC goes to maximum and tempering takes a bit more effort but is well worth it."

O1 has from .9% to 1% carbon but it is not 1095 or any other simple high carbon steel. It is loaded with carbide forming elements (often vanadium or tungsten), it takes time and temperature to bring that locked up carbon into play. Over the years I have worked with Starret, Crucible (Ketos) and Carpenter O1. Each was designated as O1 yet were all different steels to work with. Ketos lacks the vanadium the others can contain and thus does not have quite as much tolerance for over heating, but it was very affordable. My favorite was Carpenters stuff but now their sources are varying so who knows :confused:.

Sorry boys, there is no magic number for universal success. This was my typical treatment for Ketos- austenitize at 1480 for at least 4-5 minutes after rebound of the salts (this is entirely dependent on the prior heat treat. if the microstructure is heavily spheroidal perhaps longer, if it is baintic/pearlitic perhaps shorter).

I always found a discrepency between the real world and the tempering temperatures for HRC values listed on spec sheets until I started enxtending my soaks at precise temperatures. Using O1 with a vanadium content and soaks long enough to get good solutions, I found all my tempering temperatures going up in order to achieve the same old HRC values (440 F. is not uncommon for 59HRC). Abrasion resistance (e.g. edge holding) also increased noticeably.

All of this is in well controlled salt baths, (an oven should get you there as well) not in the forge or during the forging process, and I don't "aus-forge" as I understand it. Each flavor of O1 will behave differently (know your chemistry), each austenitizing heat will be profoundly influenced by what you did to the steel before the heat, and all of this needs to be geared towards your own equipment advantages or limitations. 1084 works great in a forge, for hammering and heat treating, because it is so simple and eutectoid that all you need to do is heat it up and imediately quench it, but the more complicated the steel, the more advanced your tools may need to be in order to bring out its full potential.

O1 has got a bad rap over the years because there were so many folks botching its heat treat, but almost anybody who has nailed it, is convinced that the stuff will outcut most other blade steels quite easily.
 
Kevin, you expressed that well. There is great benefit to having precise temperature control and really getting to know your steel, to achieve the best properties.
 
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