Are Crucible's comparison charts nonsense?

R

RX-79G

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Jun 23, 2006
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I realize they aren't built on numbers, but just relative values. While trying to wrap my head around the difference between various steels, I thought I'd look up S30V and CPM 154cm.

http://www.crucible.com/PDFs\DataSheets2010\dsS30Vv1 2010.pdf
http://www.crucible.com/PDFs\DataSheets2010\Datasheet CPM 154 CMv12010.pdf

What got my attention was that the Comparographs of toughness/wear resistance on the S30V page show S30V being roughly comparable to both standard D2 and standard 154cm for toughness.

But on the CPM 154cm page, its toughness is shown to be roughly twice that of both standard D2 and standard 154CM, but the exactly the same as S30V.


So one chart has S30V at the same toughness as 154cm and D2, and in another it is twice as tough. And I don't think it can be because the chart numbers are arbitrary, or D2 and 154CM wouldn't be consistent in both.

I get that these are just silly little charts, but the claims about S30V between these two documents are wildly different and make all of these comparisons completely suspect. Has anyone ever talked to Crucible reps about this kind of thing?
 
I would call crucible. 1800 365 1180. Maybe there is just a piece missing to the charts . As in the first one was done one way the second another . Who knows .
 
most the time the graph doesnt have RC numbers and that can missleading or the steels are not heat treated in the same manner
you jsut have to guesstimate and test for your self
 
I don't think it's manure but more likely inconsistencies with testing procedures. I know even when they test several blanks with the same geometry and HT they can sometimes get unexpected results. Especially with the Charpy Impact test. The toughness of CPM S30-V should be much higher than airmelted D2 or 154-CM. I have sent this thread to Crucible to get their take. I'll let you know what they find.
 
It's not nonsense, but its what I'd call unconstitutionally vague. Toughness depends on direction. Which directions are being compared? There is more than one type of wear resistance. I've seen both used by Crucible. Which one is on a particular chart?
 
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