More CPM 3v coming?

[Johnnie1801]

Just wondering now that the Tuff has been discontinued if cpm 3v will ever make a comeback? How about a sprint in the Military or PM2?

[Bodog]

Dude, a 3V millie would be bad ***

A 4V version would tickle my fancy even more

[Ankerson]

Dude, a 3V millie would be bad ***

A 4V version would tickle my fancy even more

I think CPM 4V would be a better choice also as it seems to be a more balanced steel for folders from what I have seen.

[yowzer]

I think 3V would work better in fixed blades. Like, say, a Serrata sprint...

[dogrunner]

Dude, a 3V millie would be bad ***

A 4V version would tickle my fancy even more

+1!!!
yessir, what you said!

[3rdGenRigger]

I think 3V would work better in fixed blades. Like, say, a Serrata sprint...

Oh dear lord yes!!!

[The Mastiff]

I like them both. 3V or 4V , unless pushed harder than I typically do will be totally adequate for my purposes. From a marketing stand point 4V still has that new car smell. I'd guess they sure could sell a bunch of them if it came down to it.

Joe

[Brock O Lee]

I really hope we see more of these tougher steels, rather than more of the ultra high carbide steels.

[Johnnie1801]

Dude, a 3V millie would be bad ***

A 4V version would tickle my fancy even more

I think CPM 4V would be a better choice also as it seems to be a more balanced steel for folders from what I have seen.

Hi JIm, just wondering if you could elaborate a little further? Would 4v be a significant/noticeable improvement over 3v in toughness, edge stability and corrosion resistance? Furthermore, what ht would we talking about for these steels, 60-64 hrc?

thanks :)

Jon

[tvenuto]

4V would be lower toughness, which is why (I think) Jim was saying it would be more of a balanced steel for folders, where the toughness is likely excessive given that other things such as lock and pivot may break in an impact scenario.

[Ankerson]

Dude, a 3V millie would be bad ***

A 4V version would tickle my fancy even more

I think CPM 4V would be a better choice also as it seems to be a more balanced steel for folders from what I have seen.

Hi JIm, just wondering if you could elaborate a little further? Would 4v be a significant/noticeable improvement over 3v in toughness, edge stability and corrosion resistance? Furthermore, what ht would we talking about for these steels, 60-64 hrc?

thanks :)

Jon

Hi Jon,

It can be a rather large improvement over 3V in edge retention and strength without losing too much impact resistance in the same hardness range, 3v drops a lot once you get in the 62-63 range. 4v is nice in the 63-64 range.

From what I have seen 4V actually works better at the higher HRC ranges, but that could be subjective as the steel is still new.

That's why I said in folders, could also add in small fixed blades like 5" and under to that.

However 3V is more corrosion resistant so there are trade offs to everything.

[Ankerson]

4V would be lower toughness, which is why (I think) Jim was saying it would be more of a balanced steel for folders, where the toughness is likely excessive given that other things such as lock and pivot may break in an impact scenario.

Yes, how much toughness does one really need in a 4" or under folder that one would be cutting stuff with? :D

That's something I have always questioned myself other than abusing the knife that is.

[Philo Beddoe]

What would be the point of a 3V Millie when a Cruwear Millie already exists? Cruwear and 3V are close to the same thing.

Seems pointless.

A 4V Millie? That would be way more interesting..

[ohcyclist]

I would love a 3V or 4V Millie or PM2. I assume that either/both would sell out incredibly fast.

[Joshua J.]

If 4V is significantly tougher at the same RC they should switch to that for the Gayle Bradley 2.

[Bodog]

If 4V is significantly tougher at the same RC they should switch to that for the Gayle Bradley 2.

A 4V Gayle Bradley 2 would be too hard to pass up.

[Cliff Stamp]

If 4V is significantly tougher at the same RC they should switch to that for the Gayle Bradley 2.

As a point of clarification, the idea that 3V has low toughness at higher hardness is often based on this kind of data :

- http://www.crucible.com/PDFs%5CDataShee ... 202010.pdf" onclick="window.open(this.href);return false;

The problem is that reasoning is wrong. Here is the same reasoning :

-there are far less pirates now then there used to be

-people are now dying of heart attacks much more than they used to

Conclusion : pirates prevent heart attacks

If you look at that data sheet, there is indeed a large difference in toughness when you look at the hardness at 62 vs 58 HRC. However those steel are not simply different in hardness, they are significantly different in microstructure.

At the high soak temperature, what happens is that the alloy carbide significantly dissolves into the austenite, this has two dramatic effects :

-as the carbon content in austenite rises, martensite starts forming plate vs lathe

-as the alloy goes into solution it strongly raises secondary precipitation

Both of these cause embrittlement of steel. Plate martensite is far more brittle than lathe martensite at the same hardness. All secondary carbide precipitation reduces toughness severely. In fact these two effects are so strong that if you hit the peak of them, it can make the steel far less tough even at a much reduced hardness. This even has a name, it is called TME and it is why low alloy steels avoid the 500F tempering range as it makes them brittle even though they are reduced in hardness.

In general, at the same micro-structure, hardness has a mild effect on toughness. The reason that toughness changes significantly isn't because the hardness is changing, it is because there are other changes in the micro-structure which are happening at the same time and these are what are causing the dramatic change in toughness.

If you want to know how to harden 3V and maximize the strength, toughness and apex stability then read Roman Landes posts on HF. He not only notes how to harden it, but why, on a metallurgical level, the micro-structure produces this combination of properties. Roman's writing, and other sources of actual metallurgy, is convincing makes like Keffeler to change how they view hardening these steels to maximize the properties by using known metallurgy.

As an aside, since people don't seem to be seeing failure of M4 in these folders due to fracture, 3V would be an inferior choice. On a dramatic level, since people are not seeing fracture failure issues in S110V, then those people really would not benefit at all from 3V or similar class steels. The principle for choosing a material is really simple, here is the question you ask :

-the material we are using now, how is it failing in use

Then ask this question :

-what property causes this failure

Then you find a steel that has this property increased.

[Cujobob]

4V's minimized corrosion resistance likely makes it inferior in a folding knife for most users. I also believe that the toughness of both 3V and 4V is wasted on a folding knife because the other areas of the knife being made from much weaker steel and the vast majority of users wouldn't use the knife in such a way that the added toughness would be a benefit.

[Cliff Stamp]

also believe that the toughness of both 3V and 4V is wasted on a folding knife because the other areas of the knife being made from much weaker steel and the vast majority of users wouldn't use the knife in such a way that the added toughness would be a benefit.

You really want to clarify between strength and toughness here as they are two very different properties.

In general, it is very rare for folders to fail by lack of fracture toughness because it is very difficult to actually load a folder in that manner. The only real way it is likely to happen is chipping the edge, but there is a fairly decent amount of people who actually like the performance of S110V and similar steels (10V, S90V) and these steels are very brittle with low apex stability. If that kind of steel isn't failing due to chipping then steels like 3V make no sense (for those people) unless they can't sharpen them.

[3rdGenRigger]

Or unless they want the extra apex stability to play with more acute edge angles. I haven't yet on my Schempp Tuff because it defeats the purpose of the existing geometry, but I run a more acute angle on my SuperBlue than I do my S30V because it is more stable in my experience (Albeit limited) at low edge angles. The Sage and Stretch are similar in geomoetry, though definitely not the same, but that is my basis for SB and S30V comparison.