Hardness vs. Toughness?

J

jerrywyatt77

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Feb 10, 2014
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Greetings, my name is Jerry, I am new to this forum and type of medium in general. I have a basic question for the seasoned knife users out there.

I have always been a huge fan of tanto blades for a few reasons, and for the most part will always gravitate towards them be they fixed blade or folding. However, I have recently become more concerned with the type of steel my blade is made of and it's functionality. So, I understand hardness is related to durability, resistance to corrosion, deformity, etc. I also know toughness is related to the blades impact and breaking. What I am looking for and not getting clear info on is a happy medium between the two. Typically I go for CRKT tactical knives with a 2cr13 58-62HRC, or a H&K with a 9cr13 58-60HRC. I even really like the hard durablity of Benchmade's knives with 154CM. But there are so many different types of tempered steel out there.

The actual question: Is there a steel out there that balances hardness and toughness (maybe a little more on the toughness side as I need a knife that can sustain repeated impact). and is a good all around knife?
 
There are a handful of steels that have both high hardness and great toughness.
CPM 3V is at the top tier of toughness and you can harden to 59-60
CPM M4 is also very tough and can be hardened into the low 60's
52100 is very tough and has a high harden-ability
0-1 is also very tough and can be around 60 if I'm not mistaken
Probably one of the toughest steels would be L-6. However, corrosion starts to become an issue
5160 would also be a good choice
 
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Most carbon steel with 0.6 - 1.00 carbon content with well heat treated will have a greater balance between hardness and toughness than any stainless steel.
 
Thanks much, that is really helpful. I was also looking at VG-10, but your pointers give me some things to look over and see what is available in my price range. what makers use these?
 
You said that you need a knife to withstand repeated impact. The amount of toughness you need will depend on what you're chopping. Cooked brisket wont require much toughness but seasoned hardwood knots will require very high toughness. It also depends on whether you want the steel to be stainless or not.
 
Darrin, you obviously haven't had to endure a cold plate of my ex sister-in-law's 'brisket':eek:. She couldn't understand how anything could take more than 3 hrs to smoke/cook properly...

Guys don't forget how big a role geometry and weight distribution impact this conversation. Especially if you are coming at this from the angle of getting a specific job done. Even if you are just wanting to reckon differing steel's performance over time for a given blade design, studying optimal edge geometry for a given hardness could probably use up the rest of your days.
 
I'm a big fan of A2 and CPM3V for hard-use knives. The extra toughness they bring to the table allows you to keep your edges really thin. In my experience the toughness of O1 is a little lower than those two, with CPM154 coming in after that. Having CPM154 and CPM3V as low and high benchmarks should let you use the comparison data from Crucible to make your decision.

If you want the ultimate then CPM3V is where it's at from what I've seen. A2 will match it in pretty much all normal use cases though, you have to really abuse a knife to see the advantages that CPM3V potentially brings to a knife. And from what I've seen CPM3V will start to plastically deform just a little before the point where A2 with a good heat treat will fail, so you kind of have the choice between a bent knife or a broken one on the macro scale. And when I say abuse I mean bending a 4" blade to 55º with one end stuck in a vise, not exactly a normal use case.

My knives at the moment are done in A2 hardened to 62HRC and their edges will still dent/roll rather than chip if you do something nasty to them.
 
I have been getting great reviews from 15N20. These 3/32" or 1/8" blades should not take the beating they do at Rc60.

"I just carved up some elk ribs,using the skinner knife,slammed through bones and cut through gristle,chopped through one fairly large bone..was still sharp,but hit it exactly 8 times per side with the ceramics I showed you and it's ready to cut fxxxxxg hair,!!!,,fxxxxxg love that shit!..next time will use the newest kitchen knife,or the hunting knife..decisions decisions..lmao"

This is guy with 40 years hunting/skinning use under his belt. He has never owned a custom knife before. He likes the O1 and 52100 as well, but I get the sense he really likes the 15N20. :)
 
Willie71 said:
I have been getting great reviews from 15N20. These 3/32" or 1/8" blades should not take the beating they do at Rc60.

"I just carved up some elk ribs,using the skinner knife,slammed through bones and cut through gristle,chopped through one fairly large bone..was still sharp,but hit it exactly 8 times per side with the ceramics I showed you and it's ready to cut fxxxxxg hair,!!!,,fxxxxxg love that shit!..next time will use the newest kitchen knife,or the hunting knife..decisions decisions..lmao"

This is guy with 40 years hunting/skinning use under his belt. He has never owned a custom knife before. He likes the O1 and 52100 as well, but I get the sense he really likes the 15N20. :)
Click to expand...

I love how excited people get when using a good steel with a good heat-treat!

There are so many great steels out there, I wish I had time to test all of them...
 
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