Non Optimum performance from O1

[duurza]

So I've seen videos on backyard heat treating of O1 and have read on this forum that those instructions are pretty poor as O1 requires proper temperature control and hold times to achieve optimum performance. Without ordering from the USA or paying a lot for shipping, my only readily available supply of knife steel would be O1.

Suppose I profile a kitchen or outdoors knife out of O1, heat it up in the backyard until non magnetic and hold for 10 minutes (because some instructions mention it and might as well do it) and then quench in canola. It is then cleaned up and tempered twice in a toaster oven at the required temperature and time for the desired hardness.

For sure, this process will not achieve optimum performance but is it worse off than if I used 1084 or simpler carbon steels that don't require such precise heat treatment processes? My biggest concern is time and money. O1 is cheaper and more readily available in my area (Toronto, Canada). Also, I think O1 has more options in terms of available heat treatments as it will harden up on its own due to heat loss via radiation (magnitude of energy lost to still air is not on par with radiation until 350 °C and at that point, it is equal in magnitude to radiation).

Is there any drawbacks of not getting the most out of O1 especially when it is cheaper than other steels that are easier to work with? Thoughts? Comments?

 

[Stacy E. Apelt - Bladesmith]

Canada has knife suppliers that sell steel.

Use 1084 if all you have is a back yard HT setup. It will likely make a blade superior to one done as you describe in O-1. Try as you may, it is nearly impossible to hold O-1 at exactly 1475-1500F for ten minutes in an open forge or BBQ.

You want the blade heated to non-magnetic and then about 50-75F higher. We usually describe this as "a shade redder than non-magnetic".

 

[samuraistuart]

To piggy back on what Stacy mentioned, if you're using "backyard" heat treating for O1, it is highly likely you'll end up with a blade that has the performance close to 1084, hopefully. It is indeed very difficult to hold a 25 degree window in a forge for 10 minutes or more, and I think O1 should get a solid 20 minute soak at temp. However, if you don't have access to any other steel besides O1, don't let that stop you from giving it a go. Make sure you are hotter than non magnetic, like 50-75f hotter, again as Stacy said, and hold it there for a soak as best you can.

 

[Metalhead0483]

I never really understood this. I know it's hard to get "optimal" performance out of O1 using said backyard heat treat techniques. But I have found the end results to be more than satisfactory in all the knives that I have made using those same techniques. I've certainly never had any complaints, and my own personal knives have held up quite well...

Just my $0.02.

 

[jdm61]

You can properly HT steel like O1 or W2 in a forge, but the forges typically used for that process are set up up to run at those lower temps and hold them and had a thermo couple setup. Think a Don Fogg word HT forge. i sa the late John White use a small versos of one of those and he could hold it to with in less than 5 degrees of target temp for long periods of time, but that was a specialized piece of gear. I did it for a brief time in a Chile forge with a black iron muffle pipe, a thermocouple and the smaller 1/2 inch burner setup on the of the ports.

 

[RX-79G]

O1 seemed like the solution to the fast quench problem for backyard smiths, which is why this question seems so familiar. The difficulty soaking steel at temp is the most obvious objection, followed by the fact that O1 is pretty expensive compared to a lot of other choices.

I don't doubt that someone with a steady hand and good eye might be able to judge decalescence well enough to keep temps bumping around in a 50° window, which would probably produce a blade that isn't too far off. But that is unlikely to happen with a newer smith and a relatively crude forge.


A quick google revealed Canada Knifemaker Supply, which has the 1084 you want, as well as 15N20 which can be treated similarly if you want to try some forge welding with the two.

 

[Willie71]

I never really understood this. I know it's hard to get "optimal" performance out of O1 using said backyard heat treat techniques. But I have found the end results to be more than satisfactory in all the knives that I have made using those same techniques. I've certainly never had any complaints, and my own personal knives have held up quite well...

Just my $0.02.

You can probably get sort of the right amount of carbon in solution, but if you are too hot, you will get too much, resulting in retained austentite. The chromium and tungsten won't get evenly into solution, possibly not at all, or in uneven clumps. This will all work against the performance of the blade. It might harden, but it won't be optimum. At best, you might get close to 1084, and at worst, a mess structurally.

 

[Willie71]

O1 seemed like the solution to the fast quench problem for backyard smiths, which is why this question seems so familiar. The difficulty soaking steel at temp is the most obvious objection, followed by the fact that O1 is pretty expensive compared to a lot of other choices.

I don't doubt that someone with a steady hand and good eye might be able to judge decalescence well enough to keep temps bumping around in a 50° window, which would probably produce a blade that isn't too far off. But that is unlikely to happen with a newer smith and a relatively crude forge.


A quick google revealed Canada Knifemaker Supply, which has the 1084 you want, as well as 15N20 which can be treated similarly if you want to try some forge welding with the two.

I deal with them all the time. They get most of their steel from Aldo, so their 1084 is good stuff. Rob and Marilyn are good people.

 

[jdm61]

There is some misunderstand of the whole "fast quench thing" You don't have to get the piece from the forge in 1 second or whatever the "nose" is on the TTT diagram. You have to get it from 1450or so down to 900F once you get it in the quenching in that time.

O1 seemed like the solution to the fast quench problem for backyard smiths, which is why this question seems so familiar. The difficulty soaking steel at temp is the most obvious objection, followed by the fact that O1 is pretty expensive compared to a lot of other choices.

I don't doubt that someone with a steady hand and good eye might be able to judge decalescence well enough to keep temps bumping around in a 50° window, which would probably produce a blade that isn't too far off. But that is unlikely to happen with a newer smith and a relatively crude forge.


A quick google revealed Canada Knifemaker Supply, which has the 1084 you want, as well as 15N20 which can be treated similarly if you want to try some forge welding with the two.

 

[RX-79G]

There is some misunderstand of the whole "fast quench thing" You don't have to get the piece from the forge in 1 second or whatever the "nose" is on the TTT diagram. You have to get it from 1450or so down to 900F once you get it in the quenching in that time.

The "fast quench problem" is the one where people are told that water is going to cause the blade to crack, but finding Parks 50 is so difficult that they decide to look for a steel that doesn't require a fast quenchant to get past the nose. Not talking about the moment between forge and quenchant, but the quenchant speed itself. Medium speed quenchants are easy to find.

 

[duurza]

Thanks for all of your replies everyone. I am aware of Knife Maker Supplies but since I'm 2/3rd of the country away, I would need to order 1084 which I believe would be more expensive in the end compared to buying O1 locally especially if I just need to make a cutting implement that works.

 

[woodwrkr221]

There is some misunderstand of the whole "fast quench thing" You don't have to get the piece from the forge in 1 second or whatever the "nose" is on the TTT diagram. You have to get it from 1450or so down to 900F once you get it in the quenching in that time.

This is certainly true but we still need to go from the oven or forge to the quench quickly. The steel will cool off down to below the desired quench temp pretty quickly so get the steel into the quench quickly.

 

[Runthemall]

Is there any way to quantify "optimal performance" of a NON-backyard heat treated O1 blade? I've done O1 blades in my coffee can forge and they've turned out great. Everybody seems to have their own opinion on proper heat treat, so I'm wondering if things are a bit "over-scienced" here?

 

[RX-79G]

Is there any way to quantify "optimal performance" of a NON-backyard heat treated O1 blade? I've done O1 blades in my coffee can forge and they've turned out great. Everybody seems to have their own opinion on proper heat treat, so I'm wondering if things are a bit "over-scienced" here?

Sure. When you see charts that compare wear resistance and toughness for different steels, those charts assume proper heat treat. 1050 is not a terrible blade steel, and an O1 heat treat executed haphazardly might perform similarly to 1050 heat treated correctly. The O1 blade is full going to have a lot of pearlite and other stuff that we don't want to make a blade out of in it, so the steel will behave like it has less carbon in it than it does - or worse. Or, it could end up with martensite formations and carbdes that are large and uneven, causing the blade to be fairly brittle and not take a fine edge.


That's assuming that the steel actually hardened at all, and doesn't come out below 50 Hrc on most of the edge.

 

[Willie71]

Is there any way to quantify "optimal performance" of a NON-backyard heat treated O1 blade? I've done O1 blades in my coffee can forge and they've turned out great. Everybody seems to have their own opinion on proper heat treat, so I'm wondering if things are a bit "over-scienced" here?

Yup, there is a difference. O1 is a pretty great steel that will vastly outperform 10XX steels. That is the point if the alloying. 1095 can get close if really well heat treated. w2 with its vanadium is in the same group with 52100 and O1 in performance.

Backyard heat treat makes it unlikely to get the performance of 1084 with O1. Too much can go wrong with the structure without the proper temps and soaks.

 

[duurza]

This is certainly true but we still need to go from the oven or forge to the quench quickly. The steel will cool off down to below the desired quench temp pretty quickly so get the steel into the quench quickly.

That actually depends on the starting temperature and effective surface area. If you give me the starting temperature, the ending temperature and the surface area, I can do some simulation runs and see how much energy is lost in what time due to radiation and natural air convection.

 

[samuraistuart]

That actually depends on the starting temperature and effective surface area. If you give me the starting temperature, the ending temperature and the surface area, I can do some simulation runs and see how much energy is lost in what time due to radiation and natural air convection.

Math! Oh no! he he! Luckily for use math challenged, all we need to do is make sure recalescence doesn't happen before the blade is quenched, and everything will still be in solution.