Larrin said:
...this thread has gone from discussion of 13C26 variants to heat treatment to ...
In a debate, if you can't contend a point and the truth is of no importance and you have to "win" a common method is to shift the focus directly to the opposition. It doesn't matter if there is no substance to the claims because when they are refuted you just do the same thing and be more drastic. Many people can be convinced by dramatics alone and rumors will be repeated much faster and further than any coherent arguement which refutes it. Even if an arguement is shown to be completely baseless the origional wild claims will still be spread by gossips who are far more interested in a "juicy" statement than emperical reality.
This also attracks hangers-on who love that sort of thing so seek any chance to be personal as a "me too" effect. The behavior is often so dramatic because there are a lot of people just waiting for the "ok" to attack so it can come out in a flood once they seek it is working well or at least there are no negative consequences anyway. Even if you can't actually discredit the opposition you can still win by causing enough misdirection that people forget the origional contention. Ideally the other guy sinks to your level and gets just as personal or better yet he goes further. Once he has given up facts/logic he has of course eliminated any advantage and now it just comes down to whoever is willing to go lowest wins.
Yes if you take this approach you look bad to the people who see through it critically and you will offend some people, but you lost them already when the problems were exposed and you could not counter them. You are also counting a lot of your popularity over the other person because without that inertia it can collapse on you, but again you have already lost on facts/logic anyway. Of course anyone of any intelligence sees through all of this so the question is - can you see that the Emperor has no clothes?
M Wadel said:
dont really know if thats the optimal toughness no, i believe there are some good info in "the damasteel handbook" by erasteel. supposedly brittleness occurs when tempering over 840°F
Yes, that general location is a common point for all stainless. You can likely gain slight hardness by going lower in the temper but I wonder about the toughness/strength relationship. It can be quite peaked around those temperatures. Thanks for the details on the steels. You tend to see a dramatic effect of oil/cold at high soak temperatures because these force a lot of alloy into solution and without oil/cold you will have a lot of retained austensite and secondary carbide precipitation during quenching. This is actually kind of interesting because if you do one thing to improve the properties (increase austenization temperature) but don't do the rest (oil/cold) the steel gets worse than if you did nothing.
Larrin said:
I only have experience with 12C27 and AEB-L ...
You can get 12C27m in the Mora's for really cheap like $10 or so. You might want to get a couple and regrind them to sensible profiles and compare them to the AEB-L blades and note what is the loss in edge retention for the gain in toughness/corrosion resistance. Noting of course that an individual or low scale heat treatment could probably improve the 12C27m significantly so it is basically a lower bound. You could also reharden it after contact Sandvik on how to do so as likely you are going to want to go back to the as bar state for optimal results.
hardheart said:
... that sprint run of AEB-L Paramilitaries...
I'd likely back down to 12C27 or 12C27m for a Paramilitary as I see it as more a general use knife and I would wonder if you were doing primarily fine cutting why you would want that stock thickness and that design of handle which is suited more for heavy exertion. But in general yes, I would still want 13C26 over S30V for such a knife. For those knives I rarely find the edge to be finely worn as they get used for heavier cutting so it is the toughness/hardness which is more critical in their performance. Note that these types of steels are very similar to the low alloy carbon steels, so a comparison of 52100 vs D2 is very similar to 12C27m vs S30V. Most people realize that for tool steels you don't just look at carbides and determine which steel is superior but unfortunately this is common perception of stainless steels.
DGG said:
Is a HRC "60" value only 5% harder than a HRC "57" harness value?
Not exactly but fairly close, the hardness it is calcuated as A-e where e is the resulting permanent deformation and A is a constant, 100 for a diamond indentor. So 57 HC steels will take a 8% increase in deformation over 60 HRC steels under the diamond indentor. This causes a lot of people to think that hardness doesn't matter, but what is often of critical importance isn't the hardness itself but what it implies about the steel. There are many properties which are extremely sensitive to hardness and even moving the hardness by 1-3 points can cause the toughness to be cut in half for example which is why how you harden steels is really important because the properties are often really peaked.
What a lot of people also ignore is that when you are talking about a knife, and especially the edge, it doesn't matter what the properties are on a gross scale because the edges fails on the micron level. For example if you have high amounts of retained austenite then the blade as a whole can still be strong but when you get down to the edge which is as thin as 0.1 micron when properly sharpened, how are those bits of soft austenite going to behave. Most wood workers know you can easily build heavy furniture out of knotty woods but you can't make fine detail because the knots will dominate the behavior at that scale. Now most carpenters don't think in terms of the influence of scaling structure to defect size which would be how you would discuss the math, but that is just a language, the meaning is the same.
On a similar note, if you do a hardness test and it comes out where you expect it to be a lot of makers use this to argue the steel is sound. This isn't the case. This would be looking at bread and noting that since it rose it will obviously taste right - that is obviously absurd, but so is the hardness test when used in that manner. If the bread doesn't rise then you can assume there is a problem just like if you do a hardness test and it comes out really off you know that something went wonky. However if the hardness tests right it can still be far from optimal and there are in fact many ways to get to the same hardness and have very different properties in the steel.
-Cliff
. these knives are also considered disposables, nobody ever sharpens them they just get a new one. the price of 12c27 and 12c27mod is probably the same (the mod might be just a little more expensive a few % maybe, since it has more Cr)