Toughest stainless steel ?

[tvenuto]

I think the real issue is that there is confusion regarding semantics. Toughness (engineering) is a quantifiable property of a particular material, and even there you can get more specific about meaning. Toughness (colloquial) has no rigorous meaning, and generally refers to a knife as a whole resisting damage regardless of the mechanism. Thus, people tend to get all huffy when you state that a particular material has low toughness (engineering) since they equate that with poor build quality or “fragility” which is what you would mean if speaking colloquially.

I think we have to remember that when discussing esoteric details of a handheld tool, we’ll find ourselves at the intersection subjective experience and objective facts. When the conversation straddles these two zones we need to take care to remember the distinction and recognize which side of the line our information falls on.

To beat the horse:
“S110V has generally low toughness run at ##hrc”
“Well I’ve beat the heck out of my military and never had an issue, seems like it’s plenty tough to me”

Both of these posters could be correct they’re just talking about different things. The fact that you’ve never experienced a failure with your knife has no bearing on the measured toughness of a particular steel. It’s a useful data point for other users, but might not be relevant to the question.

So before getting defensive, or assuming that some people are discounting your experience just remember that you may be talking about different things.

[Pelagic]

To me, it's easy to misuse terms when describing knife attributes. Edge retention is partially a function of wear resistance, toughness, and even corrosion resistance for example. And since there's an endless amount of combinations of tests or stress that you could put on a blade, it can be confusing when a blade passes a test in regard to whether it did so due to its wear resistance, or its toughness (or whatever), especially if you didn't witness exactly how the cuts were made. I know each term has its own clear cut definition, but even with user subjectivity aside, there often seems to be some gray area in certain scenarios regarding which term is most appropriate.

[me2]

I have a related question about toughness in steel. Are some forms of stainless steel tougher in one section than another, like certain forms of glass, or, are the properties across the board? Isotropic vs anisotropic are the technical terms. Isotropic means the properties are the same in all directions and the anisotropic materials have directional properties, like tensile vs compressive strength. Steel tends to be isotropic but I am asking if anyone here knows of stainless knife steel that is directionally-dependent?

Steel is anisotropic. Powder processed steels are less so, but still a little. The main promotion of S30V originally was its transverse toughness. The longitudinal toughness of powder processed steels like S30V is very close to conventional steels like 440C. However, in the transverse direction, 90 degrees to the rolling direction, cpm steels are tougher. Tensile and compressive strength are not really examples of anisotropic behaviour. Isotropic behavior would be something like a wood having the same tensile strength in all directions relative to the grain. True isotropic behavior is very difficult to get. Glass would be the closest I could think of, but the processing would have to be done with that in mind or it wouldn't happen.

[steelcity16]

Let's dust this one off! :D

Elmax, CPM-154, M390, AEB-L...what's the toughest??

[Larrin]

[SpyderEdgeForever]

Larrin and others: The Fallkniven and other people who are into laminated steel seem to think if you take the various super steel and laminate them, you get an even tougher end product.

[gonzokat86]

Aeb-L definitely should be one of the top “tough” stainless steels

[thewoodpecker]

I am curious. Why does CPM S35VN have such low toughness if the carbide content is lower than CPM-154/Elmax/M390/etc.?

[attila]

Is NioMax your "new steel" that you mentioned as being in the design phase a few months ago? Can you tell us more about it? Thanks.

[MacLaren]

The manufacturers don't make it easy to figure out.

If I wanted a tough stainless knife, I'd probably place a bet on a Busse ELMAX knife.

That they've actually made a few is a good clue.

+1

[The Mastiff]

Even at rc 57.5 it's not all that tough. That chart should put paid to the often repeated statement that Elmax is the toughest of stainless steels. It's a good steel but really not all that tough. Even for a stainless steel. I can't count how many times I've read that especially over at Bladeforums.

[Baron Mind]

I have been in the "kindly keep your chromium out of my blade steel" camp for sometime now. Aside from stain resistance, it is detrimental to all other characteristics we want in our knives.

Except, lately I've been pondering the effect of corrosiveness on the retention of high levels of sharpness. I find my low chromium blades losing their hair whittling edges after sitting unused for a night or two. At first I thought it might be the steel decompressing after sharpening, but it doesn't seem to happen as much with my stainless steels. I can strop the low chromes back before I start my day, but it is somewhat annoying and worrisome.

What do you guys think?

[blues]

I have been in the "kindly keep your chromium out of my blade steel" camp for sometime now. Aside from stain resistance, it is detrimental to all other characteristics we want in our knives.

Except, lately I've been pondering the effect of corrosiveness on the retention of high levels of sharpness. I find my low chromium blades losing their hair whittling edges after sitting unused for a night or two. At first I thought it might be the steel decompressing after sharpening, but it doesn't seem to happen as much with my stainless steels. I can strop the low chromes back before I start my day, but it is somewhat annoying and worrisome.

What do you guys think?

It may be mildly irksome, but not worrisome. (Imho,..YMMV)

[Baron Mind]

I have been in the "kindly keep your chromium out of my blade steel" camp for sometime now. Aside from stain resistance, it is detrimental to all other characteristics we want in our knives.

Except, lately I've been pondering the effect of corrosiveness on the retention of high levels of sharpness. I find my low chromium blades losing their hair whittling edges after sitting unused for a night or two. At first I thought it might be the steel decompressing after sharpening, but it doesn't seem to happen as much with my stainless steels. I can strop the low chromes back before I start my day, but it is somewhat annoying and worrisome.

What do you guys think?

It may be mildly irksome, but not worrisome. (Imho,..YMMV)

Yea, as they say, blade steels are all about tradeoffs, and trading a little edge maintenance for increased toughness, strength, better sharpening, and increased edge retention is a pretty good deal in my book.

I guess I should preempt any replies by stating that number of those traits, like almost everything, are dependent on heat treat, but for the most part they are factual and indisputable. And that's not to say you can get great performance out of some stainless steels, and if stain resistance is important to you I do not mean to denigrate you in any way.

Ok, there. :)

[Larrin]

I am curious. Why does CPM S35VN have such low toughness if the carbide content is lower than CPM-154/Elmax/M390/etc.?

Vanax and S35VN have similar carbide/nitride volume and look similar. M390 appears to outperform relative to those. Why CPM-154 does so much better I don’t know. Hoping to do some more samples sometime in the future.

[Larrin]

Is NioMax your "new steel" that you mentioned as being in the design phase a few months ago? Can you tell us more about it? Thanks.

Can’t say that much about it. It’s designed to have similar carbide volume to AEB-L but niobium carbide instead.

[ferider]

I am curious. Why does CPM S35VN have such low toughness if the carbide content is lower than CPM-154/Elmax/M390/etc.?

Vanax and S35VN have similar carbide/nitride volume and look similar. M390 appears to outperform relative to those. Why CPM-154 does so much better I don’t know. Hoping to do some more samples sometime in the future.

Hi Larrin, do you have a feeling where M390 goes with lower HRC (around 60) ?

[Woodpuppy]

Larrin and others: The Fallkniven and other people who are into laminated steel seem to think if you take the various super steel and laminate them, you get an even tougher end product.

Perhaps for prying or batoning, but not for edge stability.

[Larrin]

Hi Larrin, do you have a feeling where M390 goes with lower HRC (around 60) ?

Best guess is a similar slope to Vanax and S35VN. I think we have samples coming with other heat treatments. We will see.

[Larrin]

Larrin and others: The Fallkniven and other people who are into laminated steel seem to think if you take the various super steel and laminate them, you get an even tougher end product.

Perhaps for prying or batoning, but not for edge stability.

And tips tend to break more frequently than whole blades. San-mai has its uses but it’s not a cure-all.