How tough CPM-3V really is?

[J. Doyle]

So in a nutshell - if you aim for toughness you're getting tougher knife buying well done 1095 than "budget" 3V...

Even this statement can lead to some confusion because "well done" 1095 really isn't all that tough, and if you make 1095 tough it really isn't all that "well done".

Now before the ESEE fans (I like ESEE and 1095) grab pitch forks and light torches, in order to make 1095 so tough, usually it is made with thick(er) geometry and/or low(er) hardness, thereby leaving some performance on the table. If you're going to do that, one would be better off with something like 1075 or 15n20 where you could have better toughness at higher hardness with better geometry.

 

[LostCause]

Even this statement can lead to some confusion because "well done" 1095 really isn't all that tough, and if you make 1095 tough it really isn't all that "well done".

Now before the ESEE fans (I like ESEE and 1095) grab pitch forks and light torches, in order to make 1095 so tough, usually it is made with thick(er) geometry and/or low(er) hardness, thereby leaving some performance on the table. If you're going to do that, one would be better off with something like 1075 or 15n20 where you could better toughness at higher hardness with better geometry.

Now I wonder what's the deal with Terava and their 80CrV2?

I know 3V is more stain and wear resistant, but that 80CrV2 is some extremely tough stuff.

 

[hugofeynman]

I mean, kinda sad that 3V exists for so long and only few makers are able to heat treat it right.

So in a nutshell - if you aim for toughness you're getting tougher knife buying well done 1095 than "budget" 3V...

It’s more or less that. Another way of thinking is: is much much easier to mess 3v heat treatment (or other pm steel) than to mess much simpler steels heat treatment. And look at the steels that won Forged in Fire knife or death competition (I know, I know, who won where the guys that handled the knives/swords): superbly well heat treated 1075 and 80crv2. For me, no more pm steels. Just good ol simple steels (1075, 5160, 6150, 80crv2) or high alloys with extreme toughness in mind (Bohler K600, Ultrafort Maraging steel, Aermet 100 (if I can get a piece of it)…).

 

[Larrin]

It’s more or less that. Another way of thinking is: is much much easier to mess 3v heat treatment (or other pm steel) than to mess much simpler steels heat treatment. And look at the steels that won Forged in Fire knife or death competition (I know, I know, who won where the guys that handled the knives/swords): superbly well heat treated 1075 and 80crv2. For me, no more pm steels. Just good ol simple steels (1075, 5160, 6150, 80crv2) or high alloys with extreme toughness in mind (Bohler K600, Ultrafort Maraging steel, Aermet 100 (if I can get a piece of it)…).

The number of simple steels with bad heat treatments is much higher than complex steels. Forge heat treating is the best way to make heat treating more likely to fail, which is the preferred method for many knifemakers with simple steels. And simple steels have much narrower temperature ranges for austenitizing before you get grain growth, plate martensite, etc.

 

[hugofeynman]

And look, for instance, at Roman Landes recommendation to heat treat 3v:

Roman Landes Heat Treatment recomendation

:Now this is what I would recommend for heat treat cpm 3v:



1st preheat: 500-600°C, equalize

2nd preheat:800-900°C, equalize

Autenize: 1060-1070°C, equalize, soak 30-35min

Quench in Oil preheated 60-80°C

Cryo: immediately after cleaning, minimum -80°C or lower soak 30min

1st Temper: 150°C equalize, soak 2hrs, quench in water

Cryo: immediately after temper

2nd Temper: 180-200°C equalize, soak 2hrs

should give you 60+ and a fine durable grain.

You need at least two furnaces and cryo setup. And lots of TIME, and time is money!

 

[shane45-1911]

Another way of thinking is: is much much easier to mess 3v heat treatment (or other pm steel) than to mess much simpler steels heat treatment.

That is not true. Simple steels have a higher likelihood of improper HT/tempering with a narrower margin for error.

EDIT - Larrin types faster than I do, above.

 

[hugofeynman]

And look, for instance, at Roman Landes recommendation to heat treat 3v:

Roman Landes Heat Treatment recomendation

:Now this is what I would recommend for heat treat cpm 3v:



1st preheat: 500-600°C, equalize

2nd preheat:800-900°C, equalize

Autenize: 1060-1070°C, equalize, soak 30-35min

Quench in Oil preheated 60-80°C

Cryo: immediately after cleaning, minimum -80°C or lower soak 30min

1st Temper: 150°C equalize, soak 2hrs, quench in water

Cryo: immediately after temper

2nd Temper: 180-200°C equalize, soak 2hrs

should give you 60+ and a fine durable grain.

You need at least two furnaces and cryo setup. And lots of TIME, and time is money. Do you think most companies follow this exact steps? I seriously doubt.

 

[hugofeynman]

The number of simple steels with bad heat treatments is much higher than complex steels. Forge heat treating is the best way to make heat treating more likely to fail, which is the preferred method for many knifemakers with simple steels. And simple steels have much narrower temperature ranges for austenitizing before you get grain growth, plate martensite, etc.

I mean, “simple” steels heat treated in a furnace.

 

[LostCause]

The number of simple steels with bad heat treatments is much higher than complex steels. Forge heat treating is the best way to make heat treating more likely to fail, which is the preferred method for many knifemakers with simple steels. And simple steels have much narrower temperature ranges for austenitizing before you get grain growth, plate martensite, etc.

Speaking of manufacturers, they don't do their HT in a forge, now I wonder do you perhaps have any data on who gets the most out of their steel?

Example is Buck and their 420HC. I am less concerned about what steel I'm getting, and more concerned with how well is the maker heat treating their steel.

But I understand if you have no suggestions, as I know that you often use samples of steel for testing and not actual knives by manufacturers.

Any imput is appreciated.

 

[Alberta Ed]

Intriguing topic. Most commercially produced knives hold up quite well IMHO, if used sensibly; the torture/abuse tests really aren't relevant. Even "simple" steels contain various alloying elements such as nickel, silicon and manganese. PM steels with high carbide content don't lack toughness - latest example being Magnacut, for instance.

 

[Larrin]

Speaking of manufacturers, they don't do their HT in a forge, now I wonder do you perhaps have any data on who gets the most out of their steel?

Example is Buck and their 420HC. I am less concerned about what steel I'm getting, and more concerned with how well is the maker heat treating their steel.

But I understand if you have no suggestions, as I know that you often use samples of steel for testing and not actual knives by manufacturers.

Any imput is appreciated.

Buck knives is one of the few where I was able to test toughness coupons of steel while consulting for them. They asked if there were potential improvements on their 420HC heat treatment. I said it was already as good as it could be.

 

[hugofeynman]

That is not true. Simple steels have a higher likelihood of improper HT/tempering with a narrower margin for error.

EDIT - Larrin types faster than I do, above.

My bad, then. Yes, I forgot about grain growth, forge heat treatments, you’re right. So, then, I’m with the OP, why 3v knives break so easily if abused? Really bad geometry??? Paper thin???? If they are so well heat treated, something else must be terribly wrong… and I know, a knife is meant to slice, not to be used as a hammer (like I thought before 2010, when my knife obsession started. Since I joined forums and started to watch videos on YouTube, I was amazed about what people use knives for, battoning, chopping… abusing knives beyond comprehension and some survived!).

 

[Larrin]

Intriguing topic. Most commercially produced knives hold up quite well IMHO, if used sensibly; the torture/abuse tests really aren't relevant. Even "simple" steels contain various alloying elements such as nickel, silicon and manganese. PM steels with high carbide content don't lack toughness - latest example being Magnacut, for instance.

“High carbide content” is relative though. MagnaCut has half the carbide of th prior common PM stainless steels. Even less than half of carbide monsters like M390. The microstructure of that steel is not pretty.

 

[Larrin]

My bad, then. Yes, I forgot about grain growth, forge heat treatments, you’re right. So, then, I’m with the OP, why 3v knives break so easily if abused? Really bad geometry??? Paper thin???? If they are so well heat treated, something else must be terribly wrong… and I know, a knife is meant to slice, not to be used as a hammer (like I thought before 2010, when my knife obsession started. Since I joined forums and started to watch videos on YouTube, I was amazed about what people use knives for, battoning, chopping… abusing knives beyond comprehension and some survived!).

The most common reason for blades breaking easily are stress risers. Sharp corners, laser cut blades that don’t have the HAZ removed, etc. After that the stock thickness, yes. Chipping of edges from edge geometry, of course.

 

[hugofeynman]

The most common reason for blades breaking easily are stress risers. Sharp corners, laser cut blades that don’t have the HAZ removed, etc. After that the stock thickness, yes. Chipping of edges from edge geometry, of course.

What’s HAZ, Larrin?

 

[hugofeynman]

Heat affected zone.

 

[000Robert]

In my part of the world CPK is unavaliable and if you want to import it - it's crazy expensive.

So, here if you want crazy toughness options are these, from cheapest to most expensive:
Hultafors Heavy Duty
Mora Robust
Terava - their 80CrV2 is crazy tough
ESEE
ANV - apparently does Sleipner good
TOPS

None of these will quite match the combination that delta 3V has (stain resistance, edge retention and toughness). But, that is what we have.

European makers are mostly making knives that are very balanced. Meaning covering edge retention, stain resistance and toughness without any of it being extreme. So they use steels like Sleipner, Niolox and so on. And when it comes to carbon steels - 80CrV2 sees more use lately. And the Elmax of so called "super steels" - TRC is using it a lot, Fallkniven started to use it too.

I'm sorry to hear that. I don't see why they want to charge yall so much to buy stuff from the USA.

 

[Deino]

Now I wonder what's the deal with Terava and their 80CrV2?

I know 3V is more stain and wear resistant, but that 80CrV2 is some extremely tough stuff.

80CrV2 has almost no hard carbide, which contributes to its shock resistance, the down side is the wear resistance is poor. I just got my Terava 140 and I can attest this.

Laurin metal, the company that makes blade for most of Finnish production knives, including Finnish military issued knives and Terava (intended to be budget friendly version of the military one), uses the differential tempering, with the spine softer than the edge. Therefore, you can smash the spine (batonning) more with it. Since they are more of military field craft tools, durability is prioritised over edge retention.

Edit: The general durability over edge retention is a trend in standard military knives and their substitutes. Well, until they need some more specialized tools certain jobs that the parameters get to change. 55Si7 is a steel used in some standard Nato field knife/bayonet that I oddly never hear many things about, despite being the mass produced for many armies. They are made very soft by knife standard however. Does anyone have 200$ to buy one to test out for us?

 

[hugofeynman]

80CrV2 has almost no hard carbide, which contributes to its shock resistance, the down side is the wear resistance is poor. I just got my Terava 140 and I can attest this.

Lauri metal, the company that makes blade for most of Finnish production knives, including Finnish military issued knives and Terava (intended to be budget friendly version of the military one), uses the differential tempering, with the spine softer than the edge. Therefore, you can smash the spine (batonning) more with it. Since they are more of military field craft tools, toughness is prioritised over edge retention.

Are those Finish military issued knives only for militaries or they also sell for public? Can you recommend a website to see those knives? I like Terava products, maybe those are even tougher.

 

[Deino]

Are those Finish military issued knives only for militaries or they also sell for public? Can you recommend a website to see those knives? I like Terava products, maybe those are even tougher.

They are available to the public. The info that I get from, a Finnish collector website: http://www.nirvi.fi/nnbm/page93.html.
That and the fact that they are both made by Lauri metal and having the very similar dimensions (the official one is a little longer, but not by much) kind of suggest that they are the same knife in practice.
Since the knife is only available from retailers, and most of them are from Europe, I can't recommend you where to get it.

Back to the main subject, many production 3V knives are so damn thick. Cold Steel Master hunter is 4.8mm (0.1875") for 115mm (4.5") and the SRK 3V is 5mm (1.95) for 152mm (6") blade, Lion Steel new T6 3V is 5.5mm thick(!!!) for 155mm (6.03") blade... That's insane for a tough steel.