just purchased a survive knives gso 4.1 in s90v steel

[bravodelta]

I would LOVE to see a shootout between the GSO 4.1 in M390, S90V and 3V versions!! Same knife, same grind, different steels. Come on Guy, please lend a few to Ankerson.

 

[Ankerson]

I would LOVE to see a shootout between the GSO 4.1 in M390, S90V and 3V versions!! Same knife, same grind, different steels. Come on Guy, please lend a few to Ankerson.

I have one in M390, did a full test on it already....

 

[bravodelta]

Ankerson, I missed the M390 as I was away. However, your M390 4.1 review is the sole reason I pulled the trigger on the S90V version. I hope it achieves similar performance. Thanks for all the testing that you do.

I have one in M390, did a full test on it already....

 

[Ankerson]

Ankerson, I missed the M390 as I was away. However, your M390 4.1 review is the sole reason I pulled the trigger on the S90V version. I hope it achieves similar performance. Thanks for all the testing that you do.

I am sure it will be fine, just use the heck out of it.

 

[chiral.grolim]

Where do you draw your data from? I ask because for me personally there is just to many conflicting data to determine one final value to steels.

Charpy tests are known to have issues with regards to keeping standard samples from lab to lab etc.

The data are drawn from various sources including Crucible's site as well as MatWeb, and Zapp, etc. but I have actually found that these data do NOT really conflict, though perhaps your concern is the lack of "one final value"? Where the values are identical, I assume that the measured test sample was identical, i.e. one source just copied the published data from another source as I did here. In reality, the values should never be identical due to variables, rather they should fall within a measurable range for a given hardness (note that the hardness measurements themselves aren't all that precise but also fall within a range).

http://www.smt.sandvik.com/en/materials-center/material-datasheets/strip-steel/sandvik-chromflex/

I found that Sandvik testing, but it measures toughness at different testing temperatures without mentioning Rockwell hardness. We want toughness at room temperature as a function of tempering.
I sincerely doubt that 13C26 can only absorb 12 J/cm2 at 58-60 Rc, but I haven't found those figures.

http://www.seamountknifeworks.com/articles/Knife_steel_impact_toughness.pdf

I don't think Phil is Charpy-testing the steel in-house, just relying on the same supplier information we have, but i like his statement: "I think the tool steel companies are very conservative with their Charpy values. Especially on the CPM grades. For example I have been making a lot of hunting blades out of CPM 10V. The data sheet from Crucible on this steel indicates that it has about the same toughness as D-2 at the same hardness. I have found that I can heat treat 10V to about Rockwell 63 and it still has more than adequate toughness for a working knife. My experience with D-2 in the past indicates that it starts to get pretty brittle at about Rockwell 60."

Look at the impressive values of CPM-M4 in this test

http://www.zapp.com/fileadmin/downl...blaetter-Werkzeuglegierungen/CPM RexT15_E.pdf

Those CPM-M4 values correlate with Crucible's data on CPM M4 HC(HS)
No problem there.

one more:

http://www.zapp.com/fileadmin/downloads/01-Produkte/Datenblaetter-Werkzeuglegierungen/CPM 3V_E.pdf

Again, good correlation with Crucible's published data, so much that i worry it is a mere reprint.

Some good value arguments: http://www.steeluniversity.org/content/html/eng/default.asp?catid=151&pageid=2081271963

"The objective of Charpy testing is twofold:

To determine the ductile to brittle transition temperature for the steel in question.
To allow comparison between different steel suppliers and to demonstrate that a given process route consistently produces the same level of impact toughness.

... the notch acuity, some of the temperatures and the strain rate used in the test are not representative of the conditions in which many steels are used. Therefore the results of Charpy impact tests cannot be used directly to predict in-service behavior and failure characteristics, because as stated previously fracture mode depends critically, not only on the properties of the steel, but also on these parameters.

... the energy to fracture depends critically on the sample geometry... and is very dependent on the strain rate..."

We are only concerned with the ductile-to-brittle transition NOT falling within normal environmental parameters, a very narrow temperature range. After that, we are FAR more concerned with zones of embrittlement from HT & tempering. Note how CPM-3V loses toughness quickly as tempering-time/temperature is reduced, demanding careful heat-treatment to maximize its potential.

The most important point for us, as Phil's quote and also Ankerson suggest, is the part about geometry and strain rate. Knives use thin geometry that, through miniscule changes, can dramatically affect behavior when used at normal force-levels for hand-tools. A thin rolled edge can lead to brittle fracture from hand-pressure, but thickening the edge only 0.010" could prevent both rolling and fracture.

Ankerson asserts, "S90V isn't brittle at all." Well, fracture at <30 J/cm2 is a far cry from endurance up to 100 J/cm2. However, the threshold of forces exerted on the geometry of an edge 0.035" behind the edge may not reach that level in ordinary use. The S90V edge might fracture out at 0.010" under the same forces that fail to fracture a 0.010" 3V edge, but at 3x-thicker geometry you'd never notice a difference! Perhaps this is why 440C was popular and is still used despite its relative fragility. S90V gives 440C-level toughness with more than double the wear resistance.



It was proposed that in a knife of this design, with such thick geometry, one won't notice the increased wear resistance over, say, 440C. I think that Ankerson has shown that even a thick knife like this one evinces that increased wear-resistance, though perhaps not as much as a thinner knife would. But one could just as easily argue that, with such thick geometry, one won't notice the increased toughness of CPM-3V! I would love to see how much better CPM-3V performs over 440C at thinner geometries since wear-resistance should be about equal. Is that 4-fold increase in toughness noticeable?

 

[the5farrs]

I missed out on all the versions of the 4.1. They are going to make a GSO 5.1 in cpm-20cv. Which one do you think is better, the cpm-20cv or cpm-3v? Not sure which one to get.

Thanks,

Matt