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seved
11-07-2010, 04:43 AM
What is the best and most optimum hardness for O1.

Seved

Kevin R. Cashen
11-07-2010, 07:05 AM
If it is for a knife, what kind of knife? What are you going to do with it?

seved
11-07-2010, 07:18 AM
No i just mean in general.Hm Maybe utility knives.

Seved

Doug Lester
11-07-2010, 07:18 AM
Another question is how are you going to test the hardness? Is it going to be tested with an insturment or is it going to be a performance test? A hardness tester of some type, whether a machine or calibrated files, is more specific. Performance testing is something more between and estimate and wishfull thinking.

Doug Lester

seved
11-07-2010, 07:32 AM
I have a Durometer, a swedish machine for HRC testing a very good machine :).

Why i ask is, i have heard that the optimum hardnes for O1 is 61-62 HRC and that it will hold up with very thin edge with that hardnes. But i doubt that. I like O1 and use it very much, but i doubt that it is preferable.

Seved

Doug Lester
11-07-2010, 08:43 AM
Ok, now we know a bit more what we are talking about but optimal hardness is going to have to be determined by the intended usage of the blade. An HRC of 61-62 is a little high for most blades but some something that is going to be strictly a slicer, like a skinning blade, may do well with that hardness but that that would probably be a little too high for something that will get rougher use. Remember, edge retention is only one factor here, there is also the toughness of the blade to consider. A blade for rougher use may need more toughness than O1 can deliver at an HRC of 61-62 and you might need to temper 25-50 degrees higher to get a softer but tougher blade. If you want a blade with some flexability in it I would recommend something other than O1. Instrument testing can only take you so far. In the end you are going to have to design a blade for a certain job and then test it in use to see how it holds up whether it is slicing things like rope, skinning animals, preparing food, chopping wood, quartering large game, or whatever.

Doug Lester

seved
11-07-2010, 09:28 AM
Ok, now we know a bit more what we are talking about but optimal hardness is going to have to be determined by the intended usage of the blade. An HRC of 61-62 is a little high for most blades but some something that is going to be strictly a slicer, like a skinning blade, may do well with that hardness but that that would probably be a little too high for something that will get rougher use. Remember, edge retention is only one factor here, there is also the toughness of the blade to consider. A blade for rougher use may need more toughness than O1 can deliver at an HRC of 61-62 and you might need to temper 25-50 degrees higher to get a softer but tougher blade. If you want a blade with some flexability in it I would recommend something other than O1. Instrument testing can only take you so far. In the end you are going to have to design a blade for a certain job and then test it in use to see how it holds up whether it is slicing things like rope, skinning animals, preparing food, chopping wood, quartering large game, or whatever.

Doug Lester

Yes sorry i should have explaned better. Yes absolutly with skinning,slicingknives i like a bit harder blades, you dont bend and such a things with the knife and if you skining a moose its very hard on the edge and the edge will be sharp a little longer. But for a utility and such knives i prefer a little softer blade even if i have to sharp it a little more often. But to say that O1 is made for high hardnes is wrong i think. It is more what you are going to used for.
Yes i agree totaly with you, if i try to design a blade for a speciell task, and then test it for that, if you are satisfied with it, its good for use. Often its the design of the knife that is important.

Seved

LRB
11-13-2010, 05:00 PM
I use 01 exclusively, and I found that a hardness of around 58, give or take a point, is a very good range of hardness to cover most cutting projects, while allowing for easy touch up. I can work two deer without touch up, and probably three, if needed.

Kevin R. Cashen
11-13-2010, 05:31 PM
There really isn't any one best answer, it is kind of like asking "how long is a piece of string?" Yes the desired hardness level will change from a skinning knife to a large chopper, but it will also be very dependent on edge geometry. For a fine slicer, skinner or hunter from 61 on up to 63 will work nicely with O1 if the heat treat is optimal. For really fine kitchen cutlery it can also go from 63 and beyond. For large knives used for chopping 58 to 62 will work. If the heat treat is dead on so that there is optimal grain size and carbide distribution with nothing funny going on in the grain boundaries you would be surprised how hard you can leave an O-1 blade. So long as the loading is not extremely sudden impact deformation is actually more plastic than brittle even at higher hardness.

But then you get into edge geometry, the more obtuse or beefy the edge bevels, the less chance of deformation regardless of the hardness, but the less effective it will be in the cutting. A really thin edge will cut great with Little resistance but will need to have just the right hardness and conditions to support it. Heat treating with a torch or a forge with O-1 it is probably better to go with thicker edges at lower hardness, but if you have the means to hold the temperature precisely for a given time then you can go thinner and reap the benefits of the strength provided by higher hardness. Flexibility is a function of cross section and thickness, and not effected so much by hardness level like actual bending is.

DLBrothers
12-01-2010, 11:10 AM
While we are on the subject of O1 - a personal favorite of mine - How much benefit is deep cryo to O1? Seeing as how it is a complex alloy compared to 1085 for instance, it would seem that it could gain a little toughness that would benefit it at higher hardnesses. (I just put three blades in the tank to see....)