Two Diagrams from Crucible Data Sheets

[nozh2002]

Looking for CPM 3V I found this two diagrams in Cricible Data Sheets - I put them together:

Very interesting!

Thanks, Vassili.

 

[cali]

this diagrams don't have values on axes, so i'm afraid this comparition is useless.

 

[averageguy]

That is very interesting.

 

[s0rce]

this diagrams don't have values on axes, so i'm afraid this comparition is useless.

the comparison doesnt provide an abosolute measurment but It can be used as a valid means of relative comparison between the differnt alloys.

 

[Gollnick]

There really isn't a quantitative measure for toughness or even really wear resistance. What they're trying to do here is give a relative qualitative comparision. It's not scientific; I don't think it was intended to be. But it can still give a good comparison.

One of the things you can see is that many of the steels which have achieved wide-spread popularity for blades, D2, 440C, 154CM, have a very even balance between these two traits.

There are, of course, other traits to consider when selecting a steel. D2, for example, is orders of magnitude more rust-prone than 440C. And that's just one of the many traits that define a steel alloy.

 

[Jeff Clark]

Did you put together a toughness diagram with a wear resistance diagram or did you merge two toughness-with-wear-resistance diagrams? The first case insures that the toughness scales are all equivalent and the wear resistance scales are equivalent. The second case might allow for a discontinuity between two series of alloys. Since we don't have numerical values it would be easy to confuse our scales. The diagrams are very nice. I wish they included 1095 and 5160.

 

[TLM]

There really isn't a quantitative measure for toughness

Must have missed something, all those impact and Kc tests are supposed to be just that.

TLM

 

[Ritt]

Are any of the listed alloys similar to, or the same thing as, VG-10?

 

[Cliff Stamp]

There really isn't a quantitative measure for toughness or even really wear resistance.

There are several for each, toughness can be measured by impact toughness, ductility, resilence, and the elastic and plastic deformation limits. Wear is easily quantified by abrasive and adhesive material loss. You can look up the materials data for each in various ASM books, plus various journals.

-Cliff

 

[nozh2002]

Did you put together a toughness diagram with a wear resistance diagram or did you merge two toughness-with-wear-resistance diagrams?

This is two digram - one is left half, other one is right half. You may notice on both sides there is D2 and CPM 10V with same level. I just put two Crucible diagrams together as they are in their datasheets. So it is two merged toughness-with-wear-resistance diagrams from here:

http://www.crucibleservice.com/datasheets/index.cfm

First one from here:
http://www.crucibleservice.com/datash/GFSbroch2.pdf

Second one from here:
http://www.crucibleservice.com/datash/dsS30Vv4b.pdf

Thanks, Vassili.

 

[SAKguy]

Just goes to show you that there is not a darn thing wrong with 440C.

Nice chart.

 

[GarageBoy]

154CM holds an edge better than D2?

 

[Cliff Stamp]

The biggest problem is the hardness values are not listed, for example at what hardness was S30V found to have so much higher wear resistance than D2. Are people really findind S30v knives to stay sharper so much longer than D2 blades?

-Cliff

 

[WYK]

Good point, Cliff. In my personal experience, I find M2 in a Benchmade to have more toughness and wear resistance than S30V in my T2, which recently chipped so badly I tossed it. I didn't like the handle thickness, anyways

As for relevent data, CPM states how it tests it's steel, and it's results in each product description. Here's an example of M2:

PM M2 61HRC Charpy C-Notch test Impact Toughness 26 Ftlbs

http://www.crucibleservice.com/datash/dsPMM2v1b.pdf

WYK

 

[Cliff Stamp]

Yeah, Benchmade hardens their M2 significantly lower than what you find in most spec's sheets which list it fairly brittle as it is usually ~65 HRC.

-Cliff

 

[s0rce]

Good point, Cliff. In my personal experience, I find M2 in a Benchmade to have more toughness and wear resistance than S30V in my T2, which recently chipped so badly I tossed it. I didn't like the handle thickness, anyways

As for relevent data, CPM states how it tests it's steel, and it's results in each product description. Here's an example of M2:

PM M2 61HRC Charpy C-Notch test Impact Toughness 26 Ftlbs

http://www.crucibleservice.com/datash/dsPMM2v1b.pdf

WYK

those specs are mainly about cruicible's particle metalurgy version of M2

 

[STR]

It really does show how good 440C is and why. I have been saying for some time that there is nothing at all wrong with it and that many still consider it a premium knife steel.

Pretty impressive stats to compare steels with. I do wish it had a couple of my other faves in there though but I assume that 1095 would most likely be similar to 01 and that perhaps 5160 is tougher than both or somewhere in between.

 

[WYK]

those specs are mainly about cruicible's particle metalurgy version of M2

That's the idea. We're talking about Crucible here. You might want to check the thread start.

If you want to check out 'standard' M2, Crucible also has that on the very same URL I listed. However, it's likely hardened to HRC 65. My M2 Benchmade is in the 61HRC range.

As Cliff mentioned earlier, the chart at the top of this thread does not cite any specific hardness. You will have to go to every individual data sheet to see the hardness ratigns for their given comparisons. Many of these ratings aren't necessarily adequate for knife blades. And the chart says nothing of the blades ability to take an edge in the first place, or be resharpened. One of the issues folks have with 440C, and many other stainless steels, is in order for them to keep a good edge they oftenhave to be hardened to the point where sharpening is a chore. Whereas with M2 at 61 HRC, it's easy to sharpen, keeps a great edge, and is very tough - same goes for L6 at 56HRC, 52100 at 58 HRC, etc.

WYK

 

[the possum]

Thanks for posting this, Vassili. It really helps to put things into perspective. Just looking at the chart, it really makes one wonder why people even bother with steels like O-1, A2, and D2, when we now have CPM-3V available. It offers more wear resistance, and a lot more toughness than all those steels. I realize there are other factors involved, but some of these steels don't seem to get the praise they deserve. S30V is the hottest steel going, but there are several other steels that meet or greatly exceed its performance in one or both categories. For big knives or swords that will take huge amounts of abuse... how come S7 hasn't gone mainstream? Sure, different hardness levels will affect the chart, but this is certainly a good place to start when selecting a steel for a specific application.

 

[Cliff Stamp]

...it really makes one wonder why people even bother with steels like O-1, A2, and D2

It takes a lot of time to develop a new steel, you have to prototype the design, then do extensive testing to make sure the performance is there in all the catagories, then adjust the geometry to optomize it, all while adjusting the heat treatment over a range of hardness to find the correct balance.

All while doing this you could be making knives and selling them, for guys just trying to make a living without an extensive back order list and a comfortable income this can be problematic. Plus you can be guaranteed that in 1-2 years there will be a new fad steel which everyone will then clamor for to replace the one you just spent all that time doing R&D with.

What you will find is that in many cases, the makers that flip from one steel to another like flavors of soda don't do any of this, the knives don't change in geometry as the steels come in and go out, the scope of work of the knives don't change, and if you ask them for performance comparisons against the steel they just switched, good luck on getting a responce.

Your best bet as a maker is to find someone like Wilson who has a regular job as an engineer aside from being a knifemaker and who does a lot of this R&D and will make the information public. This can cut a lot of the experiement time out as he will tell you the exact times and temps he uses and how the steel behaves at each run.

S30V is the hottest steel going, but there are several other steels that meet or greatly exceed its performance in one or both categories. For big knives or swords that will take huge amounts of abuse... how come S7 hasn't gone mainstream?

Because it isn't the preferred steel for high speed operators man.

-Cliff