Combination & Compilation of Crucible's Comparagraphs

Daniel Koster

Daniel Koster

www.kosterknives.com
Knifemaker / Craftsman / Service Provider
Joined
Oct 18, 2001
Messages
20,978
How's that for some early morning alliteration?

:D


Ok....I got up too early today I guess....:p





Here's a little chart I made by carefully scaling and redrawing the various comparagraphs that Crucible (now SB Specialty Metals) has put out on the steels they offered.

Have a look, tell me what you think, and definitely let me know if you have any graph evidence contradicting any of the data below so I can correct it.

Like I said, this is their info, not mine....I just compiled and combined it into one graph. It's also not 100% inclusive, but just the more common steels.


I'd also be interested in hearing if your experience echoes what's shown in the graph. (for example, does the crazy wear-resistance of S90V make it much harder to grind/sharpen than D2)

I know there's more at play here than just their toughness/wear-resistance data....other components to the steel that factor in...(for example, A2 and O1 have very similar numbers, but A2 has a lot more Chromium in it and has better stain-resistance...and so on).

I just wanted to share this chart with y'all.

Here it is:

attachment.php


(I compiled this from 7 MSDS Data Sheets published by Crucible)


Dan
 
Last edited:
I've been at this a while and I still don't understand the difference between the terms "toughness" and "wear resistance".

They sound synonymous to me.

Can someone explain - in simple english - the difference between them?

Sorry for the painful newbie question.
 
It's simple. One is "tough" another is "resistant"
Didn't you get that in most it is a marketing trick? Personaly I don't give a S..T to a parameter wich does not have a clear reference and a scale.
For example HRC. It has well known units, references and the test equipment is calibratable.
Tensile Strength- the known size and shape of steel sample is stressed and precisely measured. No place for the trick.

But when it is "toughness" - it is the same as "beauty".
I can make a chart where the rubber will be tougher than O1.... so what? Yes, the rubber is tougher if stretched 50%.
 
Thanks for the chart I am looking forward to the discussion, I have gone back and forth through those charts many times trying to make a comparison, this is great.
 
Not sure how much weight I'd put into those graphs. They've got 440C as being more wear resistant than both A2 and O1? And, not just a little bit, either. Looks like 440C is about twice as wear resistant than O1. :rolleyes:
 
Los Angeles said:
I've been at this a while and I still don't understand the difference between the terms "toughness" and "wear resistance".

They sound synonymous to me.

Can someone explain - in simple english - the difference between them?

Sorry for the painful newbie question.
Click to expand...

Toughness is impact strength. Wear resistance is a measurement of how long you can go between sharpenings.

Dmitry.M said:
It's simple. One is "tough" another is "resistant"
Didn't you get that in most it is a marketing trick? Personaly I don't give a S..T to a parameter wich does not have a clear reference and a scale.
For example HRC. It has well known units, references and the test equipment is calibratable.
Tensile Strength- the known size and shape of steel sample is stressed and precisely measured. No place for the trick.

But when it is "toughness" - it is the same as "beauty".
I can make a chart where the rubber will be tougher than O1.... so what? Yes, the rubber is tougher if stretched 50%.
Click to expand...

It's no marketing ploy, Dmitry. It's formulas, Charpy testing, and hard science by the steel makers themselves. There's no hype. Just facts. You might need to spend some time reading the MSDS sheets - it's all there, very clearly spelled out with lots of testing results freely published. Google it...;)

Matthew Gregory said:
Excellent Explanation of Toughness
Click to expand...

Great link - good reading there. :thumbup:

Patrickknives said:
Thanks for the chart I am looking forward to the discussion, I have gone back and forth through those charts many times trying to make a comparison, this is great.
Click to expand...

:thumbup:


Danbo said:
Not sure how much weight I'd put into those graphs. They've got 440C as being more wear resistant than both A2 and O1? And, not just a little bit, either. Looks like 440C is about twice as wear resistant than O1. :rolleyes:
Click to expand...

Why wouldn't it be? Wear-resistance is influenced by the presence of vanadium and chromium content (IIRC). O1 has little/none of either.

Dan
 
Even assuming the scales are non linear or whatever, 440C is supposed to be just about as good as D2 except full stainless?

Not to mention hardness would have an impact on the toughness/wear resistance.
 
440C contains no Vanadium either. And, some O1 does contain Vanadium.
 
most important thing is missing from the chart thats the hardness tested liek for 9v its tested at 54 RC and thats the target HTY for that steel jsut liek the 3v is also run on the softer then it could be side for the extra tughness but even at62 3v is plenty tuff
the only steel on that chart i have not worked with is A2 and S90v (but have worked s125v )
 
Daniel Koster said:
It's no marketing ploy, Dmitry. It's formulas, Charpy testing, and hard science by the steel makers themselves. There's no hype. Just facts. You might need to spend some time reading the MSDS sheets - it's all there, very clearly spelled out with lots of testing results freely published. Google it...;)
Click to expand...

Ok.
In what unuts this "toughness is measured? "toughs"? "figs"? Ohms? Kilograms\second?
What material has 100units of toughness?
What material has 0 units of toughness?

The same applyes for the wear resistance.

Those scales are compilative, it is convinient and understandable measure of COMPLEX of steel properties. But it is not what can be reliably and directly measured.
Toughness and wear resistance are CALCULATED, not measured.

Hardness can be measured directly.
Tensile strength - directly.
Module of elasticity - directly.
Etc.

From consumer point of view and from traders point of view "toughness" and "wear resisnance" are very convenient and good "parameters". It is easy to choose and easy to sell and promote.

But!!!
Anmyone can write the formula to calculate let's say the "GOODNESS" of steel.
Put there all measurable and calculatable parameters, add more calculatables - and here we go. The ultimate formula is ready.
What it will tell ME? - nothing. But it is true and honest. Because the result is calculated from the real measurable steel properties. No trick there. It's all good. It's all true.

I am exadurating a bit.
I understand what tougness ane wear resistance are. University degree you know...
But knifemakes should not rely on those secondary propeties. Look at the basic measurable numbers. It's all there.

I have to add something. Every steel can be processed to make it tougher or harder. How that is reflected in those graphs in the first post?

So. I conclude my point. Toughness and wear resistanse are convenient compilative properties, in general. Agree. But they do not accurately reflect the real life.
 
I have found a few more sheets to study and am in the process of making this chart more accurate. Like I said, these aren't my claims, they belong to the manufacturers.

Dmitry - spend some time reading the MSDS sheets on the various steels - here is a link: http://www.burgessknives.com/34601.html - he seems to have a pretty decent collection. Also, look into Charpy testing. It is a very scientific process. I think you may find your suspicions unwarranted.
 
butcher block - you are correct. It seems each steel was tested at its ideal hardness level. If you look at the MSDS sheets in detail, you can see the hardness curves. The quantities for the comparagraphs correlate to those "peak" numbers.
 
While Charpy is a scientific test it sometimes does not correlate with the real world ! Many people look at the numbers as being exact for their application , not realizing that the tests are done under specific conditions which may not be the same as what they have.
 
ASTM G83-96 Standard Test Method for Wear Testing with a Crossed-Cylinder Apparatus

1.2 When the rotating and stationary bars are of the same material, wear test results are reported as the total volume loss in cubic millimetres for the rotating and stationary cylinders. The manner of recording the results also specifies the particular test procedure used. The value is obtained by adding the volume loss of the rotating member to the volume loss of the nonrotating member. Materials of higher wear resistance will have lower volume loss.

Note 1-To attain uniformity among laboratories, it is the intent of this test method to require that volume loss due to wear be reported only in the metric system as cubic millimetres (1 mm = 6.102 X 10 in. ).

Charpy impact test
The quantitative result of the impact test—the energy needed to fracture a material—can be used to measure the toughness of the material and the yield strength. Also, the strain rate may be studied and analyzed for its effect on fracture. reported in ft-lb or joules.
 
You know, I'm not stupid enough to think EPA Highway Mileage and City Mileage ratings for my car are going to translate into actual results for me - but they are sure as heck useful in comparing different vehicles against a common standard.

These comparagraphs are a lot like that. They are a simple, useful comparison, that tells enough of the story to be useful, without overwhelming the reader. If you want to be overwhelmed, check out the stickies. :D

Thanks for this Dan

Rob!
 
KnifeMaker.ca said:
You know, I'm not stupid enough to think EPA Highway Mileage and City Mileage ratings for my car are going to translate into actual results for me - but they are sure as heck useful in comparing different vehicles against a common standard.

These comparagraphs are a lot like that. They are a simple, useful comparison, that tells enough of the story to be useful, without overwhelming the reader. If you want to be overwhelmed, check out the stickies. :D

Thanks for this Dan

Rob!
Click to expand...

Best post yet! Thanks, Rob!
 
zaph1 said:
So, if I don't want to ever have to sharpen again, I should use nothing but s90v? You got any, Rob?
Click to expand...

kind of they also make s110v and if you dont need SS there is 15v
but you trade into a blade a bit more likly to have a chappy edge or to brake the tip off (oooo and the HT for them is extreeme)

i havea blade in s125v and while its holds an edge like nothikng i have ever seen i find that i chip the edge up in my use (read abuse) like cutting most of a role of kawool and still beig kind of sharp
 
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