Comparative Abrasive Wear Resistance

N

nullack

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Nov 17, 2008
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Gday knifemakers,

I'd like to try to pool together abrasive wear test data. Ideally, the data should be from a standardised abrasive wear test like the ASTM G65 abrasive wear test and also include the rockwell C grade hardness as we know that effects the test result too.

So far Ive managed to find the data below but Im keen to know other results especially 52100, CPM3V and CPMS30V.

My personal tests are showing anecdotal effects in two areas (which obviously could be observed in error):

1. a breakage mode from a lack of toughness and strength on the edge.
2. a wear mode where the greatest proportion of wear seems to be caused by abrasive wear. Note I believe that other types of wear are still a factor though.

abrasive_wear.gif
 
Thanks for creating this very interesting thread.

Is there a free copy of how to set up the ASTM G65 abrasive wear test apparatus? If I can set it up, I have CPM 10V (A11) to use as the standard reference, and a bunch of other steels I could test.

The only thing I can find is this:
http://www.cladtechnologies.com/Articles/Wear Testing/Wear Testing.htm

Seems like one would need to find a consistent source of sand, or just use silicon carbide, but then, that might put the high-carbide steels at less of an advantage.
 
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This is a little bit off topic, but I'd like to make two observations.

1: There are a few different "wear" mechanisms, and I'm not sure any of the tests do a great job of simulating wear of a knife edge.

2: I frequently see edge degradation as a function of edge roll or chipping rather than pure abrasive wear (you've seen the same thing). And this is in fine cutting tests in cardboard and leather, not chopping. I think that a knife that is reasonably sharpened for cutting performance needs edge stability as much or more than raw abrasive wear resistance, and some of the things that improve abrasive wear resistance values work against edge stability. For example, S30V has a high carbide volume and a lot of chromium - both things that reduce edge stability. So, despite really good abrasion "numbers", the real world edge retention of an S30V blade really isn't that special compared to other good steels with good HT with much lower abrasive wear resistance values.

I'm just mentioning this because you might be disappointed if you're trying to correlate edge retention with abrasive wear resistance numbers. I tried that once too. But other than that it will be cool to see what you come up with.
 
Nathan I think you make an excellent point.

I do conduct personal cutting tests but it's limited by the wife approval factor of buying more materials :) also it's hard to relate poorly standardized personal tests to fellow knifemakers tests.

I've been trying to connect the phrase edge retention to the billions spent on research within the tool and die industry. I don't think cutting tools exist in a bubble seperate to all that money spent on professional research. I could be wrong, but edge retention seems to be mainly about strength, hardness, toughness and abrasion resistance. There seems to be other minor factors such as adhesive wear resistance and corrosive wear resistance where Ive seen rust dull the edge. All of these properties can be measured using standard tests and terms that is directly comparable. I can't look up a tool steel book and directly compare edge retention.

I fully welcome any reasoned criticism or suggestions of the approach.
 
Most every steel company uses a different wear resistance test, so it's difficult/impossible to compare them all, and that's even before getting to more rare grades. Rope cutting and catra is basically a wear resistance test that is more knife-specific, it would be more useful to do your own tests comparing whatever steels you're wondering about. General comparisons can be made otherwise.
 
Wear comparisons are a constant moving target. Nathan has hit the nail on the head with the testing not being completely relevant. Wear is a complicated mechanism involving many variables. Hardness, toughness, fatigue strength, carbide type, carbide volume, etc. All these properties are engaged when a material is put into a "wear" environment. Nullack, the G65 test is one that is very sensitive to hardness more than carbide content. Notice how the A11 improves dramatically as the hardness increases. Same with D2. When stamping steel parts made from 10V punches, they can easily outlast D2 5-10 times in the same application. This is where the carbides now have the upper hand. When you stamp heavy gauge steel 3V can outlast 10V because the edge chips off rather than wears. I'll dig up some of the data I have in my files and get it in here. It's good to see a lot of different wear tests, then look at the dominant property resisting the wear. Fun stuff.
 
Larrin said:
Most every steel company uses a different wear resistance test, so it's difficult/impossible to compare them all, and that's even before getting to more rare grades. Rope cutting and catra is basically a wear resistance test that is more knife-specific, it would be more useful to do your own tests comparing whatever steels you're wondering about. General comparisons can be made otherwise.
Click to expand...

Yeah if I can get the directions to set up the apparatus, I could test all the steels obtainable, on my own. CATRA results are not available for most steels, unfortunately. The few results that are available, have no hardnesses assigned to them. Also, just a couple degrees difference in the edge bevel can give dramatically different results.

Satrang said:
Nullack, the G65 test is one that is very sensitive to hardness more than carbide content. Notice how the A11 improves dramatically as the hardness increases. Same with D2. When stamping steel parts made from 10V punches, they can easily outlast D2 5-10 times in the same application. This is where the carbides now have the upper hand. When you stamp heavy gauge steel 3V can outlast 10V because the edge chips off rather than wears. I'll dig up some of the data I have in my files and get it in here. It's good to see a lot of different wear tests, then look at the dominant property resisting the wear. Fun stuff.
Click to expand...

Hardness also plays a big role in the wear resistance of knives, so this G65 test seems like a plus to me. CPM 10V outlasts everything in the knife world too, but it did not outlast D2 5 times in various rope-slicing/cardboard-cutting tests.

The punches seem to favor adhesive wear resistance over abrasive, doesn't it? I'm not too sure. What steels are favored in punches?
 
It's a VERY easy test to set up if we replace the rubber/sand wheel with a common belt grinder. The specimen size is 1/4" x 1" x 3", which I can easily make.

g65apparatus.jpg


The setup is not completely standardized with regards to rotation speed, but intralab results are typically within 3% of each other. The results are easy to normalize by using CPM 10V as a standard.

g65apparatus2.jpg
 
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Im glad you found the info useful Cotdt. I look forward to you sharing any test result data with us. Obviously the results will need to be taken logically in context for reaching conclusions but I do think looking at abrasive wear resistance has some place of relevance to knife materials.

Also Ed I'm keen to see any info you can dig up and share. I think part of the reason why we dont have a clear definition of what edge retention is, is because of the complexity you mention. It seems most of us agree it is to do with two items - breakage and wear. With breakage, strength and toughness is easily measured. For wear, its a more complex thing to define and measure but I dont think it is impossible.
 
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