Originally posted by Ed Severson
The nominal chemistry for S30V:
Carbon: 1.45%
Chromium: 14.00%
Vanadium: 4.00%
Molybdenum: 2.00%
Comparison time, based on metallurgy/content, Ed Severson's commentary, and some educated guesswork:
D2
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Carbon: 1.4 - 1.6%
Chromium: 11-13%
Vanadium: 1.1%
Molybdenum: 0.7-1.2%
420V
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Carbon: 2.3%
Chromium: 14%
Vanadium: 9.0%
Molybdenum: 1.0%
BG-42
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Carbon: 1.15%
Chromium: 14.5%
Vanadium: 1.2%
Molybdenum: 4.0%
S30V compared to D2:
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* CPM process especially, but secondarily the high vanadium content should help refine grain structure significantly vs. D2. That means finer edges if you want them, and plenty good response to coarser stones for a grabby edge if that's what you want (D2's forte). May have less propensity for ripping out big carbides during extended slicing.
* More Vanadium content in S30V means more carbon is tied up in vanadium carbides (very hard... edge holding & abrasion resistance benefit). Couple more vanadium with more chrome, & that means less carbon tied up in chrome carbides I'm guessing, and therefore more free chrome at surface to oxidize to Chromium oxide which boosts corrosion resistance (iron oxide) vs. D2.
* similarly high carbon content should yield similar attainable hardness figures (also born out by Severson's comments that Rc 60-62 is very doable and useable)
* Crucible's tests show better toughness than D2, and more toughess is always good if edge holding isn't compromised. D2 is well below A2 in toughness, so S30V should fit in between somewhere.
S30V compared to 420V:
======================
* S30V has less Vanadium, so at the limit, less abrasion resistance.
* still apparently enough free chrome to be similarly stainless, but I'd guess S30V would be a bit below 420V here. Would like to see lab salt water or other testing results. The old "slice a lemon and don't clean knife for a day" test would be illustrative also.
* Clearly if S30V give's A2 a run for it's money in toughness dept, it'll significantly surpass 420V in toughness, the benefit for trading off somewhat lower ultimate edge holding.
* grain structure should be similar, i.e. CPM process.
S30V compared to BG-42:
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* CPM process should yield as good or better grain structure refinement given optimum heat treatment
* more Vanadium + plenty more carbon = better edge holding and similar if not higher attainable hardness
* same amount of chrome, along with more vanadium but with more carbon, means what... corrosion resistance should be similar probably?
* tougher is better if edge holding not a tradeoff, and it shouldn't be with so much vanadium.
* S30V trades molybdenum for vanadium. This should help grain structure, and help edge holding a bit as vanadium carbides are harder than molybdenum carbides. Yet there is enough molybdenum to prevent pitting type corrosion.
* one guy on the forums (a hunter type from Colorado, but his name slips my memory ... Jeff ____ ) indicates that he finds molybdenum content equals harder to sharpen. If so, tradeoff should make sharpening the same if not a bit better for S30V vs. BG-42.
[side bar 1: I consider 440V to be fairly well obsoleted by 420V. My read of the Crucible literature leads me to believe that Crucible thinks the same thing. 440V doesn't do anything as well as 420V from what I can tell. Best I can figure, 440V might be somewhat easier for the production vendors to deal with both in grinding and heat treating (slightly lower austenizing temp). Otherwise, 440V is more brittle and less corrosion resistant than 420V.]
[side bar 2: Phil Wilson commented to me that Bob Loveless really liked A2's edge holding and toughness, and suggested that if he hadn't committed to making a stainless knife as one of his primary goals, he'd have otherwise settled on A2 long ago. This is what prompted Wilson to look into 3V, since 3V is a "souped up CPM version of A2" more or less.]
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