High Carbon Stainless

Joined
Mar 6, 2012
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804
Will high carbon stainless patina or darken any? Specifically Boker?
I picked up a Boker awhile back and when I looked at it, the seller told me it was carbon steel. It does say high carbon in pretty big writing on the tang, but under it stainless, which is much smaller and harder to read and I missed that when I bought it. Can't find much info out there. Thanks in advance.
 
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Sep 21, 2010
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In my experience high carbon stainless usually refers to 420/440 variants. Very stainless steels that won't take a patina.
 
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Feb 25, 2001
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I have a few Camillus folders in stainless steel, from the late 1980's to early 1990's, that have developed 'patina-like' spots on the blades and springs. No real rust or pitting anywhere on the knives, but just a few nagging spots. The spots are probably due to the rather coarse finish on the blades, where moisture had seated in at some point, or improper storage. I assume that these Camillus knives are 440A steel.

Nothing as nice as a real carbon steel patina though, I'm afraid. Just ugly spots.

You can see some in this picture:

nGN6Nnqh.jpg
 
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Apr 12, 2009
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'High carbon stainless' is essentially anything with 0.5% or more carbon (the minimum to be called 'high carbon' steel of any kind, whether stainless or not), and ~12% chromium content (the minimum to be called 'stainless'). By that definition, it's not going to take a natural 'patina' (by oxidation) like a non-stainless 'carbon' steel will, though it can be etched or stained to emulate a somewhat greyer 'patina-ish' look. When stainless steel 'oxidizes', it's not a dark iron oxide that forms, but a very thin & essentially invisible layer of chromium oxide, which reacts more immediately to the presence of oxygen, and therefore prevents the iron in the underlying steel from oxidizing. That is how it's 'stainless' (which means it 'stains LESS', but still won't quite be rust-proof).

The minimum 0.5% carbon requirement (give or take ~0.5%) is what allows most decent cutlery steels to be hardened by heat treat, which then allows the steel to take and hold a relatively sharp, thin and durable edge. So, almost any reputable cutlery designed to take and hold a sharp edge will likely meet that 'high carbon' definition, whether stainless or not. The 'high carbon stainless' moniker could therefore be applied to almost any decent stainless steel used for sharpenable knives; that would mean essentially everything from 420HC (which was created and named to meet that 'High Carbon' definition, as other variants of '420' had less carbon) and up. Other 'cutlery', like stainless flatware (knives, forks, spoons) will usually contain lower amounts of carbon (maybe much lower), which then limits or prevents their ability to be hardened for edge-holding.

Chances are, the 'high carbon stainless' blades in Boker's traditional knives will very closely approximate that minimum 'high carbon stainless' standard, in something like 420HC or equivalents from Germany/Europe, maybe China, depending on where the steel & knife materials were sourced. The 'high carbon stainless' labelling is sort of a catch-all for the most basic stainless blades. Higher-alloy specialty steels will usually be specifically identified (440C, 12C27, etc), as that's usually a selling point in itself.


David
 
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Joined
May 12, 2015
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1,759
I had my Buck 110 stuffed away for a couple of months after I moved to Nebraska. There's more humidity here than Colorado. I finally dug it out and it was rusted but not in the way Carbon Steel rusts. It was a little here and a little there. The rust was rust red and kind of chunky, you'd have to see it to understand.
Anyway you wouldn't want that kind of rust on anything so I got some stainless steel polish and polished the rust off.
Stainless steel can rust in extreme situations, in my case it was stored a way with little air movement and such. Since restoring the blade,I have forgotten to dry it off a couple of times and no rust showed up, just water spots that were easily wiped off with a towel.
Before Case obviously acqiessed and started offering stainless steel, they railed against stainless steel with ads that 'Stainless Steel only stains less'.
In short, from my experience, you will not get a patina on stainless steel, the rust that may show up is ugly and you will want to polish it off.
 
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