Hardness vs Wear Resistance?

[Cynic2701]

This thread is quite long, and very informational, if sometimes confrontational. I will take the time, later, to read it more closely.

One variable that I believe would be virtually impossible to eliminate are the variances in the sharpening of the edge being tested. I cannot think of a way in which the sharpening of the cutting edge can remain constant for every edge being tested.

 

[Ankerson]

This thread is quite long, and very informational, if sometimes confrontational. I will take the time, later, to read it more closely.

One variable that I believe would be virtually impossible to eliminate are the variances in the sharpening of the edge being tested. I cannot think of a way in which the sharpening of the cutting edge can remain constant for every edge being tested.

We can get them close enough to the point that it won't matter at all in the results....

 

[Premiumsteel]

This reply is about concerns about consistent hand sharpening of blades to be tested for edge retention. What about machine sharpening as done by CATRA.

We had 3 steels blind tested by CATRA in England. We sent them 3 heat treated blanks, all tempered to as close as 61.5 Rc as we could get. The samples were 1" x 5" and ground to .060" thick. CATRA sharpened the blanks themselves and then ran their tests to measure initial sharpness(ICP is their term) and edge retention (TCC is their term).

We tried to eliminate as many variables as possible, by using same size blanks, same hardness level, and had the sharpening done in CATRA's lab.

The blades were tested on the automatic CATRA. Is this an objective test method? If not, what could be done to improve the test?

(other than of course doing 10 or more test samples per grade tested)

 

[BITEME]

wow, this is awesome guys ,your answering questions I've had for a while ,all while I'm enjoying a cup of joe on a saturday morning -thank guys

 

[Folderguy]

You have to have a solid base for cutting rope to get consistant results I believe. The way I test anyway. As long as you are doing the same thing, cutting the same way all the time the results will be consistant and repeatable. I can get it down to + or - 10 cuts so that is very consistant and I can hang my hat on that. The rope is much more abrasive than the wood I am cutting on.

Sharpness, well as long as I use the EP and match the bevels like I do and test the sharpness Like I do I am convinced in the data. The edges settle down after about 100 cuts anyway so it's good data.

Jim, perhaps you've posted it already, but I must have missed it.

Could you give us a idea of how, say an S30V blade, or any other one you've tested and is common, say a 440C or an AUS8 or 154 CM, does using your setup? I've never tried the kind of testing you do, and if you could give me a sort of baseline of the kind of results you get with any one blade at a specific HRC? And then perhaps compare that to another blade in one of your other categories. If the edges settle down after about 100 cuts, does that mean they lose their ability to continue to cut the rope well?

 

[Ankerson]

Jim, perhaps you've posted it already, but I must have missed it.

Could you give us a idea of how, say an S30V blade, or any other one you've tested and is common, say a 440C or an AUS8 or 154 CM, does using your setup? I've never tried the kind of testing you do, and if you could give me a sort of baseline of the kind of results you get with any one blade at a specific HRC? And then perhaps compare that to another blade in one of your other categories. If the edges settle down after about 100 cuts, does that mean they lose their ability to continue to cut the rope well?

I have 154CM, AUS-8 on the list, 154CM was at 61 HRC.

What I ment by the edge settling down means it will stabilize after so many cuts. That's something you would see if you started testing different steels, you would start to see patterns develop.

 

[Folderguy]

I have 154CM, AUS-8 on the list, 154CM was at 61 HRC.

What I ment by the edge settling down means it will stabilize after so many cuts. That's something you would see if you started testing different steels, you would start to see patterns develop.

Thank you. You've mentioned that your results are in the 10 cuts range, that is that when you test a blade, it's results are repeatable and the variance with that blade is usually within 10 cuts accurate, or something like that.

When you tested the 154CM at 61HRC, how many cuts did it perform given the conditions you established for your tests?

 

[Ankerson]

Thank you. You've mentioned that your results are in the 10 cuts range, that is that when you test a blade, it's results are repeatable and the variance with that blade is usually within 10 cuts accurate, or something like that.

When you tested the 154CM at 61HRC, how many cuts did it perform given the conditions you established for your tests?

I don't post raw data for a lot of reasons, one is that if someone else started cutting they might not get the exact results I get.

THat's the thing about testing, it becomes your data that you can compare too and your patterns.

It doesn't matter if I get x number of cuts and you get y number of cuts doing the samething, it's the groups they fit into in relation to the other steels that matters in the end.

If you did it the way I do exactly you would start to see some steels get the exact same results, like say 30 cuts, all the steels that got 30 cuts would be in the same group ect.

You might not sharpen the same way I do, your rope might not be the same as mine and the way you cut might be different.

 

[Folderguy]

I don't post raw data for a lot of reasons, one is that if someone else started cutting they might not get the exact results I get.

THat's the thing about testing, it becomes your data that you can compare too and your patterns.

It doesn't matter if I get x number of cuts and you get y number of cuts doing the samething, it's the groups they fit into in relation to the other steels that matters in the end.

If you did it the way I do exactly you would start to see some steels get the exact same results, like say 30 cuts, all the steels that got 30 cuts would be in the same group ect.

You might not sharpen the same way I do, your rope might not be the same as mine and the way you cut might be different.

Great!

I'm just trying to get a grip on the real differences. Your rankings have 6 or 7 levels, if I remember correctly. How big a difference typically is there when going from one group to the next? Is it really noticeable?

 

[Ankerson]

Great!

I'm just trying to get a grip on the real differences. Your rankings have 6 or 7 levels, if I remember correctly. How big a difference typically is there when going from one group to the next? Is it really noticeable?

They are noticeable differences, the difference between the categories will be decided based on YOUR data and how tight you keep your variations in the specs for the knives. The tighter you tighten the variables the tighter the categories can be.

I removed as many as I can doing it by hand.

While not set in stone or the last word on anything my data is good for the way I test and with the standards I have set.

 

[Folderguy]

They are noticeable differences, the difference between the categories will be decided based on YOUR data and how tight you keep your variations in the specs for the knives. The tighter you tighten the variables the tighter the categories can be.

I removed as many as I can doing it by hand.

While not set in stone or the last word on anything my data is good for the way I test and with the standards I have set.

One of the things I've noticed with AUS8, for example, is the degree to which different blades made from that steel have performed for me. You've mentioned in some of your posts that Cold Steel seems to have really gotten the heat treatment of AUS8 really down. Non Cold Steel knives I have in AUS8 seem to be quite a bit softer, and won't hold an edge as well. One of them is awful, and I'm almost ready to chuck the knife (NOT!)
From what I heard, 440C is very similar to AUS8, but I have a Boker Plus production knife made in 440C that apparently is way harder than the AUS8 steels I have from Cold Steel. How I "know" this comes from the way the steels react when I sharpen them on a Worksharp. WAY harder in the 440C. Could it be that the 440C has been hardened to maximum hardness and may be a bit brittle, while the AUS8 is tempered better? If AUS8 were hardened to maximum hardness and not tempered at all, how hard could that be?

 

[Ankerson]

One of the things I've noticed with AUS8, for example, is the degree to which different blades made from that steel have performed for me. You've mentioned in some of your posts that Cold Steel seems to have really gotten the heat treatment of AUS8 really down. Non Cold Steel knives I have in AUS8 seem to be quite a bit softer, and won't hold an edge as well. One of them is awful, and I'm almost ready to chuck the knife (NOT!)
From what I heard, 440C is very similar to AUS8, but I have a Boker Plus production knife made in 440C that apparently is way harder than the AUS8 steels I have from Cold Steel. How I "know" this comes from the way the steels react when I sharpen them on a Worksharp. WAY harder in the 440C. Could it be that the 440C has been hardened to maximum hardness and may be a bit brittle, while the AUS8 is tempered better? If AUS8 were hardened to maximum hardness and not tempered at all, how hard could that be?

The steels have to be tempered for stress relief or ugly things can happen.

There is a balance that has to be met, and that will depend on the use of the knife and the standards set by the manufactor to the one doing the HT.

There isn't a simple answer to any of it.

 

[Folderguy]

The steels have to be tempered for stress relief or ugly things can happen.

There is a balance that has to be met, and that will depend on the use of the knife and the standards set by the manufactor to the one doing the HT.

There isn't a simple answer to any of it.

I didn't think there was a simple answer .

So, is it fair to say that some of the steels in your listing could jump into a higher category depending on the quality of the heat treatment they receive?

 

[knarfeng]

One of the things I've noticed with AUS8, for example, is the degree to which different blades made from that steel have performed for me. You've mentioned in some of your posts that Cold Steel seems to have really gotten the heat treatment of AUS8 really down. Non Cold Steel knives I have in AUS8 seem to be quite a bit softer, and won't hold an edge as well. One of them is awful, and I'm almost ready to chuck the knife (NOT!)
From what I heard, 440C is very similar to AUS8, but I have a Boker Plus production knife made in 440C that apparently is way harder than the AUS8 steels I have from Cold Steel. How I "know" this comes from the way the steels react when I sharpen them on a Worksharp. WAY harder in the 440C. Could it be that the 440C has been hardened to maximum hardness and may be a bit brittle, while the AUS8 is tempered better? If AUS8 were hardened to maximum hardness and not tempered at all, how hard could that be?

In this case, you are looking at composition differences, not heat treat differences.

440C is significantly different from AUS8.

AUS8 does not have enough carbon to form significant amounts of carbides. 440C does. This gives 440C better wear resistance, but it it doesn't take the fine edge that AUS8 takes.

For most folks, AUS8 takes a finer edge than 440C, but 440C holds the edge that it does get longer than AUS8.

 

[Ankerson]

I didn't think there was a simple answer .

So, is it fair to say that some of the steels in your listing could jump into a higher category depending on the quality of the heat treatment they receive?

Some could yes depending on hardness and the tempering process.

That's the reason I put in the HRC hardness on the blades I had tested, it does matter.

 

[Ankerson]

In this case, you are looking at composition differences, not heat treat differences.

440C is significantly different from AUS8.

AUS8 does not have enough carbon to form significant amounts of carbides. 440C does. This gives 440C better wear resistance, but it it doesn't take the fine edge that AUS8 takes.

For most folks, AUS8 takes a finer edge than 440C, but 440C holds the edge that it does get longer than AUS8.

That's very true, no way one can turn AUS-8 into ZDP-189 or 440C into S90V, it's just not going to happen due to the different alloy content of the steels.

But results can vary greatly even at the same hardness depending on the tempering process, that can really throw a wrench into the works.

 

[knarfeng]

It would take a significantly crappy heat treat on the part of the 440C blade maker for it to not out-perform AUS8.

 

[Ankerson]

It would take a significantly crappy heat treat on the part of the 440C blade maker for it to not out-perform AUS8.

That's likely.

Just too many variables to make solid predictions all the time unless the steels are a lot different. Then you should be able to get a good idea just based on the alloy content alone.

Something like S90V and S30V, I can pretty much guarantee that S90V will give better performance just based on the alloy content.

 

[knarfeng]

That's likely.

Just too many variables to make solid predictions all the time unless the steels are a lot different. Then you should be able to get a good idea just based on the alloy content alone.

Something like S90V and S30V, I can pretty much guarantee that S90V will give better performance just based on the alloy content.

440C and AUS8 are enough different that, if it is really 440C and not mislabeled 440A, then it's a pretty sure thing that the 440C will outperform the AUS8. All other things being equal.

What confuses the issue more than heat treat is blade geometry. Blade geometry has more impact on the force necessary to cut than alloy or heat treat does.

 

[Ankerson]

440C and AUS8 are enough different that, if it is really 440C and not mislabeled 440A, then it's a pretty sure thing that the 440C will outperform the AUS8. All other things being equal.

What confuses the issue more than heat treat is blade geometry. Blade geometry has more impact on the force necessary to cut than alloy or heat treat does.

Blade geometry can be huge, really huge as can edge angle, edge finish.

Or 440C is at 54 and AUS-8A is at 59 or something stupid like that.

Steels can also vary between batches so that's another variable and sometimes they can make changes to the steels over time, that's another one.

That's why it's impossible to rate steel in order from 1 to 200 and be accurate about it, way too many variables to even try.