8cr13mov vs s30v

So, a thread comparing my least favorite steels. Ought to be renamed barf vs puke.

One is cheapo stainless, the other is vastly overrated. Just my opinions. At least with 8cr you know you will be getting average performance at best.

I love reading about all of the differences, but when it comes down to it its really hard to compare and contrast steels because there are too many variables. One company's 8cr maybe better than anothers s30v. With s30v, I've yet to find any consistency whatsoever. I've had it by Benchmade, Spyderco, ZT, Strider and a few others.

Personally, I will take Cold Steel's AUS-8A over most of the s30v I own/have owned.
 
There is nothing wrong with 8Cr, but S30V is overall a much more premium steel. Companies like Spyderco and Kershaw make some excellent value priced knives using 8Cr, S30V is going to raise the price substantially if used.

I won't repeat what others have already said, but another thing to add about S30V is that it is one of the few steels that were specifically engineered for use in knife blades.
 
Very good point. I think that is what I was saying in an earlier post in this thread where I referenced s30v to Crucible and Chris Reeves. Thank you for being much more to the point!
 
davek14 said:
I learn much in these threads on knife steel. I will never be close to an expert but more of a dilettante.

The above statement says a lot. There is more than the hardness of a metal. There is also how "tough" it is. Toughness in this case being a finer, harder grain structure?

"Tough" was always a bit hard for me to wrap my head around.

Stainless is a pain to machine even though it is soft. They say it's tough". Toughness in this case meaning it's gummy and hard to rip apart, even though it bends and deforms easily.

Toughness in a carbon steel machete means the edge will roll before it breaks, it's not brittle.

There's abrasion resistance and other factors also I suppose.
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Dave,
The terminology and the different ways different people use it can boggle the mind!

Go here for layman's definitions, These are the ones I use since I am a knife maker but I am not a metallurgist.

http://metals.about.com/library/bldef-Toughness.htm

Have fun.
 
The linked definition above pretty much is the metallurgical definition of impact toughness. Simplified a little, toughness is the ability to withstand impact loading.
 
me2 said:
The linked definition above pretty much is the metallurgical definition of impact toughness. Simplified a little, toughness is the ability to withstand impact loading.
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I've also heard impact loading referred to a a Charpy test.
 
IMHO getting to technical, 8cr decent Chinese steel, s30v much better Crucible steel. Bam the end. Lol
 
I hate 8CR specifically because I think it is over hardened. I'm a fan of 9CR though as it does pretty well in my experience.
 
davek14, Ive been into knives for a couple years now and this is what I have gathered, both from lurking on BF and elsewhere. I may be wrong in some areas, so I encourage you to also cross reference with the other much better sources that reside here

Toughness is the ability to not snap under lateral stress (this includes chipping at the edge, which is just the steel snapping in a place where it is very thin). Tough steels tend to roll at the edge rather than chip, but steels that are both tough AND hard usually dont do either (the magical balance)
Carbon steel is very tough. When you get to stainlesses, it gets more complicated because you have to factor in all of the other elements that are added that form carbides in the steel. These carbides increase wear resistance, but usually have a negative effect on toughness. The different elements in their different proportions interact with one another in a delicate balance, with some elements being there as a way to increase toughness, and others to increase wear resistance and or corrosion resistance, etc. In general, stainless steels are less tough by nature than carbon steels. That said, the toughest carbon steels usually dont have the best wear resistance (which, along with hardness, edge geometry, etc, contributes to the edge retention of the steel)

In all steel, toughness relates in a complicated way to several factors, such as the chemical composition of the steel, the hardness it is run at, and how well it is heat treated. Each factor is interconnected with the others and makes for a very complicated system. For instance, if you took a blade of s30v and ran it to 64HRC, it would chip very easily. But if you took a compositionally tougher steel (meaning the chemical composition lends itself to toughness better) like m4, you could still get decent toughness at the same hardness. And with the ability to stay tough while having better edge retention from being run harder, m4 is therefore usually regarded as a "better" steel. But then if you did the same thing with the m4, but botched the heat treat, the end result would be bad regardless of whether you got the other factors right or not.
You see? Everything is interdependent and oh so complicated. But I digress. The main thing to know is most steels become less tough (more brittle) as they are taken to higher hardnesses, but just how hard you can run the steel depends on the chemical composition. "Better" steels are usually capable of being run harder without loosing too much of their toughness. This is because of their better composition and grain structure, but also can depend heavily on how well the heat treat is done. A bad heat treat can make s30v worse than 8cr13mov very easily.......

And this of course is all very simplified and in no way complete. Im still learning myself. (honestly, Im not sure if I even made any sense in this post.... but it made sense in my head! :eek:)
Welcome to the confusion:) I think im getting to the point where id rather just enjoy the darn steel than try to understand it!
 
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Rhinoknives1 said:
I've also heard impact loading referred to a a Charpy test.
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Impact toughness is measured with a Charpy test, among others. Toughness is a little confusing because when someone says a steel is tough on a knife forum, I've seen them mean anything from tough to grind to tough in impact. There is also a different type of toughness called fracture toughness, though it's rarely mentioned on knife forums. It is a measure of how resistant a material is to failure in the presence of flaws. Low fracture toughness is a problem when a knife blade chips when sharpened with a coarse edge but works fine with a polished edge. The most dramatic example of this is a ceramic blade. The above issues of rolling vs. chipping and bending vs. breaking when lateral loads are used is more a function of ductility, strength, geometry, and possibly fracture toughness.

For what it's worth, basically no cutlery steel is really all that tough with regard to impact, with a few exceptions (S5, S7, L6). Saying something like M4 or S30V is very tough is like saying I can run really fast. It's only true in a relative sense, like if you watch me run on a track by myself and have never run before yourself. The minute someone shows up that is really fast, I'm not anymore. The good news is for most knives, impact toughness isn't much of an issue. Choppers and knives used for batoning do require impact toughness, but for most folders, it's not much of an issue.
 
me2 said:
Impact toughness is measured with a Charpy test, among others. Toughness is a little confusing because when someone says a steel is tough on a knife forum, I've seen them mean anything from tough to grind to tough in impact. There is also a different type of toughness called fracture toughness, though it's rarely mentioned on knife forums. It is a measure of how resistant a material is to failure in the presence of flaws. Low fracture toughness is a problem when a knife blade chips when sharpened with a coarse edge but works fine with a polished edge. The most dramatic example of this is a ceramic blade. The above issues of rolling vs. chipping and bending vs. breaking when lateral loads are used is more a function of ductility, strength, geometry, and possibly fracture toughness.

For what it's worth, basically no cutlery steel is really all that tough with regard to impact, with a few exceptions (S5, S7, L6). Saying something like M4 or S30V is very tough is like saying I can run really fast. It's only true in a relative sense, like if you watch me run on a track by myself and have never run before yourself. The minute someone shows up that is really fast, I'm not anymore. The good news is for most knives, impact toughness isn't much of an issue. Choppers and knives used for batoning do require impact toughness, but for most folders, it's not much of an issue.
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Very true perspective and very informative. Thank you for the post, after all, most everything is relative to something!
 
HRC isn't what's important. The microstructure is what's important. HRC is a quick way to check if the steel is more or less at the target hardness.
 
You can take some steels to over 70 HRC. Böhlers S290 Microclean comes to mind. It will make a great die or punch, but its not the best choice for a knife.
 
me2, thanks for the info man. I now realize just how little I actually know about steel!

In regards to your statement about relativity, I wasnt saying that m4 is a very tough steel, only that it was tougher than s30v. The fact that it was all just relative was a given, but I guess my over simplification may have caused some confusion. Things dont usually come out on paper as well as they do in my head :o
 
Krissig12 said:
me2, thanks for the info man. I now realize just how little I actually know about steel!

In regards to your statement about relativity, I wasnt saying that m4 is a very tough steel, only that it was tougher than s30v. The fact that it was all just relative was a given, but I guess my over simplification may have caused some confusion. Things dont usually come out on paper as well as they do in my head :o
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Oh, I wasn't really referring to your post specifically. I see people talking about toughness and say things like that. Stuff like S30V is a tough steel or M4, or D2. While its true they may be tough enough for whatever they're being used to do, they aren't tough in any real sense when compared to steels made with high toughness in mind. You are absolutely right that the relationship between all these things is fairly complicated. There are some trends though.

Regarding the 2 steels in question, I tested a Griptillian in S30V and a Cara Cara in 8Cr13MoV a couple years ago and couldn't tell a difference in edge retention. Now, you have to know that my testing is limited in scope. I tested them for push cutting, using thread on a scale to measure sharpness. After about 100' of cardboard, they would take the same effort to cut the thread. Had I kept going, the S30V would have eventually pulled ahead, but I, and many others, sharpen well before that point.
 
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