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Hi D! Just sent my email about the 4261 P BK 10.25" chef knife to them. Hoping to own one soon. How's your chef knife working?
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Sandvik Hardening Guide
- Thread starter Razorsharp244
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What would be a good standardized test for knife steels? I agree CATRA does generate some strange results.
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Despite this thread being a year old, I'll ask what CATRA results are you referring to as strange? The only CATRA test results I've ever seen released for blades of equal geometry are the Diamondblade tests, and they do not seem strange to me given known or assumed HRc's or wear resistance.
Now what does seem strange (and for me puts doubt on the entire test regimen and all the test results) to me are some test results where knives with lower hardness and lower wear resistance get better edge retention results than a knife with harder and more wear resistant steels - now that doesn't make sense to me.
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Strange results like hearing that Talonite (45 rc?) outperformed several high end steels. Anyone who has used Talonite know that it doesn't hold an edge at all. But the CATRA is right, Talonite is more wear resistant. Just not something people see in the real world.
I can imagine that some knives with lower hardness and wear resistance in certain situations performing better than higher end steels if microchipping is an issue. An extreme case could be 1095 versus a ceramic (solid oxide/carbide) knife. The ceramic knife should outlast the 1095 twenty times over but in the real world this doesn't happen.
The CATRA basically tests slicing on abrasives. Probably a better test for abrasive wear resistance is simply to sharpen it (assuming blade geometry the same). To me the primary purpose of a knife is to concentrate a massive amount of force onto the microscopic edge that is 0.4 microns thick, ie. cutting into material. This would be primary influenced by strength (proportional to hardness), and is not the same phenomenon tested by the CATRA.
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You have oversimplified it.
The inherent edge retention of an alloy, as Broos points out, is most often a combination of hardness and wear resistance. That is true in the real world as much as in the CATRA tests. There are types of cutting that depend on one more than the other. Some types of cutting are dependent on hardness, other types on wear resistance, but most often both factors combine to provide the edge retention.
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Like you say, there are many different kinds of wear depending on the type of cutting. CATRA only measures a small part of it, ie. slicing soft abrasive materials. This also has some dependancy on hardness as the ASM G65 wear resistance test shows, but what I describe is push-cutting non-abrasives, which has an even stronger dependancy on hardness.
Actually, push-cutting wear resistance might only depend on hardness. I notice no difference in wood carving regardless on what steel I use, they all lose shaving ability under roughly equal use, seems to only depend on hardness. So for my use, it really is that simple. I may do a passaround of an S125V knife (behaves like solid carbide but tougher) and an 1084 knife (in theory no carbides) at the same hardness, and see what others think about this.
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Hi Broos,
I think that the standard CATRA measures re-grindability instead of wear resistance.
The sand paper (paper doped with silicon oxide) that you cut will wear down the edge after a number of cuts. This method has some flaws:
1. If the carbide size is bigger than the size of the silicon oxides in the paper the carbides will tend to "bump" the oxide particles in the CATRA paper. Imagine digging in the ground and hitting a big rock. The rock stays and you cant dig deeper.
2. If the carbides are small they will be plowed or dug out of the steel. Again with your shovel you will not notice small rocks.
This means that for fine carbide steels and carbon steels the CATRA will give strange results compared to coarse grades. The difference in results should be huge, even if the hardness works against the coarse ones. Someone mentioned Talonite. There is the perfect example.
Other flaws with traditional CATRA. Why test what you dont cut? Who would cut sandpaper with a knife? Few will cut anything harder than wood or bone and then the wear mechanisms are different.
So my conclusion is that CATRA measures how fast you can grind away a sharp edge. That would be reversable so it means that it measures how fast you can put a new edge on the knife. Re-grindability.
However, the rope-cutting CATRA actually tests something relevant to knife-use.
//Jerker
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Jerker, Yes a Catra test cutting rope comes pretty close to something relevant to use. I have been trying to correlate actual use in the field in a hunting situation-- field dressing and skinning with the results that you get cutting 5/8 rope. I am a hunter and make a lot of hunting knives.I would have thought that rope would be greater challenge to the edge since there is more force applied -- up to 25lbs as opposed to say something around 5 lbs applied to the knife when skinning an animal. The CATRA test on rope I think is measuring the rate of degregration of the edge of the steel. Combination of abrasive wear, and compressive strength. The hand test is measuring that plus tensile strength (edge is not always exactly vertical to the cut) and the ergonomics of the total knife. That is leverage, handle fit, effects of the curved edge (belly) sharpening method. The hand test is introducing many more variables but is truly testing the total knife. The best way to get an idea of predicted performance is to make the exact same knife with different steels and then to sharpen exactly the same. Since there are so many varibles and since there is a lot of "feel" I have to look for large differences. In spite of all this some knives stand out. In fact you can tell the difference in the first 50 or so cuts. Back to the original thought---
I have recently had the opportunity to field test some of the higher carbide percentage, high hardness steels. One test was on skinning and American Bison and the other was the same knife on 4 Pronghorns. On the Bison I counted the total number of cuts for the skinning operation. In spite of the lower force the Bison knife dulled about 2 times faster (cut for cut) than if I had been doing the same number of cuts on 5/8 rope even at the higher force. The same effect was noted on the Pronghorns. The conclusion is that animal skin and hair is way more abrasive than I had previously thought. The Bison knife, after the field use, would still cut rope with less than 25lbs force and the edge was restored with just a few strokes on a crystalon stone. What I am saying here is that in spite of testing methods and the various testers philosophy the only way to really know how the total knife performs is to use it in the way it was designed to be used. Yes this is all antedotal (sp?) but I did it for my own use and to calibrate testing with reality for my own knife making pursuit. Also when I hear that "my knife did 20 deer and was still sharp enough to do an elk" I am very skeptical. Next hunt I will have the foresight to bring some hide home and do some more controlled testing..
Phil
I have recently had the opportunity to field test some of the higher carbide percentage, high hardness steels. One test was on skinning and American Bison and the other was the same knife on 4 Pronghorns. On the Bison I counted the total number of cuts for the skinning operation. In spite of the lower force the Bison knife dulled about 2 times faster (cut for cut) than if I had been doing the same number of cuts on 5/8 rope even at the higher force. The same effect was noted on the Pronghorns. The conclusion is that animal skin and hair is way more abrasive than I had previously thought. The Bison knife, after the field use, would still cut rope with less than 25lbs force and the edge was restored with just a few strokes on a crystalon stone. What I am saying here is that in spite of testing methods and the various testers philosophy the only way to really know how the total knife performs is to use it in the way it was designed to be used. Yes this is all antedotal (sp?) but I did it for my own use and to calibrate testing with reality for my own knife making pursuit. Also when I hear that "my knife did 20 deer and was still sharp enough to do an elk" I am very skeptical. Next hunt I will have the foresight to bring some hide home and do some more controlled testing..
Phil
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Hi Phil, I could not agree more with you. Actual tests are what really counts in the end. And how different properties (wear resistance, toughness, corrosion resistance etc) are valued by the individual.
Also the CATRA tests examines an idealized cut. No bending of the edge which means that it does not show edge degradation due to chipping or edge-rolling.
In my experience rolling and chipping are the most common reasons for regrinding. Not lack of wear resistance.
CATRA has it's uses but it should be used carefully with a good understanding of what it actually tests and what it doesn't test.
//Jerker
Also the CATRA tests examines an idealized cut. No bending of the edge which means that it does not show edge degradation due to chipping or edge-rolling.
In my experience rolling and chipping are the most common reasons for regrinding. Not lack of wear resistance.
CATRA has it's uses but it should be used carefully with a good understanding of what it actually tests and what it doesn't test.
//Jerker