Steel Testing YouTube Videos

[Chumango]

Yes I have heard that carbide tear out is a myth, even with Michael Christy's tests with s110v he had minimal difference in tests when sharpening with softer abrasives as compared to using only diamond stones, I have done no scientific research myself but most people consider it a myth

Almost all the sharpening done in that test for carbide tearout used the same type of abrasives for both blades. One blade did have some diamond media used, but that was only part of the total sequence of abrasives used, and if I recall correctly it was an earlier stage - still finished with non-diamond.

[Supersteelsteve]

He has interesting opinions. He believes carbide tear out is 100% a myth.

I've never seen evidence to support carbide tear out. I've looked at over 300 hand sharpened knives with a loupe, never seen it.

Carbide tear out would be an interesting topic for Larrin to research and write up.

My theory behind why carbide tear out is more myth than fact.

It's kinda 2 fold.


First, alot of guys talk about alumina oxide abrasives and ceramic abrasives as if they are two separate things.

Ceramic abrasives are made from alumina oxide. Matter of fact alumina oxide is used in the production of glass.

The spyderco UF is a ceramic stone made of alumina oxide with a hardness rating of 9 Mohn which is harder than vanadium carbide. Now that hardness is from the process and there are different levels of alumina oxide with different levels of hardness. So alumina oxide can cut vanadium carbide.

Then It comes down to apex size.
Sharpness is based on apex size... the finer the apex the sharper the knife.

Vanadium carbide is 2-3 microns in size.
A human hair is between 18 and 120 microns in diameter.
That means we can have an apex at 9 microns in size, a hair whittling edge.. and never have to cut the vanadium carbide.

Also , I feel that if we brough an apex to 2 microns....if the steel could even hold that fine of an edge... we would be just as likely to experience micro chipping as we would tear out..

And on that note .. can we even perceive a 2 micron tear out ?

Again... just my theory.
Feel free to dismantle it lol

[sal]

We did some research with carbon tear out in 440C a while back. I'll try to get to it this weekend.

sal

[Deadboxhero]

Oh Snap, Steve is in the house!

Wad up G! :cool:

He has interesting opinions. He believes carbide tear out is 100% a myth.

I've never seen evidence to support carbide tear out. I've looked at over 300 hand sharpened knives with a loupe, never seen it.

Carbide tear out would be an interesting topic for Larrin to research and write up.

My theory behind why carbide tear out is more myth than fact.

It's kinda 2 fold.


First, alot of guys talk about alumina oxide abrasives and ceramic abrasives as if they are two separate things.

Ceramic abrasives are made from alumina oxide. Matter of fact alumina oxide is used in the production of glass.

The spyderco UF is a ceramic stone made of alumina oxide with a hardness rating of 9 Mohn which is harder than vanadium carbide. Now that hardness is from the process and there are different levels of alumina oxide with different levels of hardness. So alumina oxide can cut vanadium carbide.

Then It comes down to apex size.
Sharpness is based on apex size... the finer the apex the sharper the knife.

Vanadium carbide is 2-3 microns in size.
A human hair is between 18 and 120 microns in diameter.
That means we can have an apex at 9 microns in size, a hair whittling edge.. and never have to cut the vanadium carbide.

Also , I feel that if we brough an apex to 2 microns....if the steel could even hold that fine of an edge... we would be just as likely to experience micro chipping as we would tear out..

And on that note .. can we even perceive a 2 micron tear out ?

Again... just my theory.
Feel free to dismantle it lol

[vivi]

We did some research with carbon tear out in 440C a while back. I'll try to get to it this weekend.

sal

Curious to hear what you discovered during those tests.

[sal]

The first time was bout 20 years ago. we were making a "Challif" for a Kosher chicken processing plant in New York. The Rabbi said that our MBS-26 in our kitchen knives was the best steel for their processing. They ground them so the edges were .01 mm thick. He said that they shipped our Santoku model to Israel to be reground into Challif's. Our kitchen knife maker didn't want to make them so we sourced a different steel from the same foundry as MBS-26 was proprietary to the maker. MBS-26 has about .95-1.05 carbon. We decided to use MRS-30 which had about 1.15 carbon and the rest of the chemistry was very similar to MBS.

We were getting complaints that the edge was "chipping". I flew to Japan with samples and met with Prof Onoue, who is a leading metallurgist in Japan. We Magna-fluxed the samples and under the microscope, we could see minor chips. Prof Onoue said that the MRS-30 had too much carbon for the very thin edge being used and the carbides were breaking out. This was an ingot steel. We were just beginning to experiment with powdered metals at the time. The plant couldn't use them because the the chickens necks need to be cut with such a sharp knife that they cannot feel the knife. If there is a nick, the chicken might feel the knife. Kosher means that the animal was killed with no fear when the animal is killed so it doesn't affect the meat. The Rabbi's are constantly sharpening their knives and there is an inspector that goes around with a loupe to inspect the edges.

The 2nd time was when we had a metallurgist on staff and I sent him to another metallurgist in the Midwest that had discovered carbide break-out in 440C on very thin edges. He taught our guy how to test for it.

sal

[Bodog]

So carbide tearout is real. After all these years.

[Crux]

Hi all,
I’m watching a YouTube channel that compares blade steel from different manufacturers, Spyderco PM2s and Para 3s being common comparables. The author suggests the heat treat on all the spyderco models / steels are the same, respective to the test conditions and his results. Check it out and share your thoughts. Supersteel Steve is the YouTube channel.

The overwhelming majority of people in the knife "community" have no idea what they're talking about.

You are such a pleasant person with your endless critiques. Any chance you can add something positive to the conversation sometime?

[Pelagic]

So carbide tearout is real. After all these years.

Yep. What people need to realize is just because someone claims carbide tearout exists, doesn't mean they're claiming it's a huge issue or that it must be avoided in order to obtain a very sharp edge. There certainly is a difference between an edge in which the carbides have been cut versus an edge in which they are either still intact or torn out, but in real world use can anyone really tell the difference? Certainly not everyone can. But if you're an edge snob or a perfectionist things like this can bug you. But I think edge angle, the grit rating of the products used, whether or not you have a microbevel, and other specifics of the sharpening methods used are more important than whether or not you cut the carbides.

[sal]

I believe that carbide, or carbon collecting at the edge is eliminated with powdered metals, though I an not a metallurgist and don't have that knowledge. Also our experience was with razor thin edges, much thinner than would be practical.

sal

[JacksonKnives]

Larrin's post about edge chipping covers a lot of the theory and some comparisons of toughness effects from a few different carbide structures:
https://knifesteelnerds.com/2018/05/28/ ... -of-edges/ under "Crack Initiation vs Fracture Toughness."

[JacksonKnives]

I believe that carbide, or carbon collecting at the edge is eliminated with powdered metals, though I an not a metallurgist and don't have that knowledge. Also our experience was with razor thin edges, much thinner than would be practical.

sal

What Larrin reports could be interpreted this way: basically that PM helps "tear-out", but doesn't solve all the problems. (High volumes of carbides, even tiny carbides, seem to help cracks propogate.)

Tough/fine grained steel definitely makes a bigger difference at low edge angles. It wouldn't surprise me if factory edge angles won't show the difference in many cases; I had to take S90 down to 12° to really see a difference in stability (a rod resting on the edge at 30° loaded with 15lb) compared to CPM-M4 in the test I did. In that test, M4 rolled while S90V popped out a chunk.

[Doeswhateveraspidercan]

I think that all testing is valuable and offers some useful information. We use a CATRA and it's going often. All of our test Mules are identical in size, thickness and edge geometry. Trying to reduce variables as much as possible. Rc is based on optimal hardness as recommended by the foundry, though we will sometimes deviate to experiment. Also, the CATRA test does not pass through the material so only the edge is being tested. Friction, when passing through material sometimes skews results.

sal

How does Spydercos S35VN compare in hardness to the knives Chris Reeve puts out? It always seemed to me his S35VN was harder as in held a sharp edge longer. My conparablies are the Spyderco Paramilitary2 and Reeve Nyala

[Supersteelsteve]

The first time was bout 20 years ago. we were making a "Challif" for a Kosher chicken processing plant in New York. The Rabbi said that our MBS-26 in our kitchen knives was the best steel for their processing. They ground them so the edges were .01 mm thick. He said that they shipped our Santoku model to Israel to be reground into Challif's. Our kitchen knife maker didn't want to make them so we sourced a different steel from the same foundry as MBS-26 was proprietary to the maker. MBS-26 has about .95-1.05 carbon. We decided to use MRS-30 which had about 1.15 carbon and the rest of the chemistry was very similar to MBS.

We were getting complaints that the edge was "chipping". I flew to Japan with samples and met with Prof Onoue, who is a leading metallurgist in Japan. We Magna-fluxed the samples and under the microscope, we could see minor chips. Prof Onoue said that the MRS-30 had too much carbon for the very thin edge being used and the carbides were breaking out. This was an ingot steel. We were just beginning to experiment with powdered metals at the time. The plant couldn't use them because the the chickens necks need to be cut with such a sharp knife that they cannot feel the knife. If there is a nick, the chicken might feel the knife. Kosher means that the animal was killed with no fear when the animal is killed so it doesn't affect the meat. The Rabbi's are constantly sharpening their knives and there is an inspector that goes around with a loupe to inspect the edges.

The 2nd time was when we had a metallurgist on staff and I sent him to another metallurgist in the Midwest that had discovered carbide break-out in 440C on very thin edges. He taught our guy how to test for it.

sal

Thanks for the info sal.

I've worked in kosher kitchens and butchered chicken "kosher"
The kosher butchers I worked with used honing rods (a steel)religiously ( haha) . They would smack the **** outta those edges against the honing rods.


They did this because one of the requirements for a meat being kosher is the throat must be cut ear to ear in one motion so the animal bleeds out humanely. ( like you said , they don't know they are being cut)


How were you guys able to tell that what they were experiencing was from carbide tear out and opposed
To just edge damage from honing, or the very thin edges sliding up against the chickens spine?

[Chumango]

The Nyala is 58-59. CRK folders are 59-60, the same range as Spyderco.

[Mstach07]

Steve,
Great video on 52100 vs 154. Keep up the great work.

[jasonstone20]

Carbide tear out during wear is a real thing, this is how medium to high carbide steels wear, by chipping. It is a completely different matter to say that you sharpened a knife and had carbide tear out due to abrasive used. This is what is in dispute, not that it cannot happen, it can, it is just rare and thereby not a common problem. Also, it is interesting that a steel like 440C/MBS 30, not a PM 'Super Steel' was victim of carbide tear out when taking to a thin edge. This is because the steel doesn't have a high edge stability as Dr. Roman Landes describes, while MBS 26 has a good level of edge stability. Also, those are chromium carbides, which can be cut with common abrasives, not the Vanadium carbides often blamed for carbide tear out. It is going to be greatly informative to see the Spyderco report on the MBS 30 carbide tear out problem.

[jasonstone20]

Steve,
The 52100 vs 154cm video is great. It is amazing how the steels rank when you measure to high sharpness.

[sal]

How were you guys able to tell that what they were experiencing was from carbide tear out and opposed
To just edge damage from honing, or the very thin edges sliding up against the chickens spine?

Hi Steve,

the Rabbi's said they were getting nicks. It was not until we examined the Magna-fluxed edge under a microscope that we could see cracks. The conclusion was from Prof Onoue. I have to trust his judgement. He is so revered in Japan that the government lets him cut core samples out of ancient Swords for research.

sal

[anagarika]

Thank you Sal, and others. I didn’t expect discussion about Youtube can be this educational.