Exotic steels not real steel?

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USCGGM

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Feb 24, 2010
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I got the Spyderco Opfocus product guide in the mail and in the back index section they a wealth of info (very cool, Spyderco!) including descriptions of steels. In the "exotic steels" section they describe it as not true steels and give ZDP-189 as the example. My question is, what makes it not a true steel and what others fall in this category?
Just curious. Thanks.
 
Perhaps because ingot steels top out at 2.1% C, and then the iron/carbon alloy is called cast iron.
 
If you're talking about Talonite that's a cobalt alloy not iron based. You can harden iron with nitrogen also .IIRC H-1 has that .
 
They use ZDP as a example because I believe its technically a ceramic or near that state.
 
I may be wrong, but I think to be considered steel an iron alloy has to have between 0.3%-2.5% carbon content. Above or below and categorization changes.
 
yep has to do with carbon content. I forget the range, but Wikipedia says above 2.1% is cast iron. Also H1 is a nitrogen-iron alloy, and so not steel. Additionally it is important to not that some HSS are barely steels at all; some of them are more like cemented carbide with an iron binder. All the terminology dates back way before powdered metallurgy technology, and so many of the steels we use today could not have been produced.
 
H1 has carbon. Just not very much.

As for high carbon iron alloys being called "steel" even if it technically isn't, I really don't see a problem with that. Because a) if it's not steel, what do you call it? and b) the definition of "steel" was created years ago before modern metallurgy began to stretch that definition.

If Spyderco started marketing knives in ZDP-189 cast iron, I doubt they'd be selling very well.
 
USCGGM said:
I got the Spyderco Opfocus product guide in the mail and in the back index section they a wealth of info (very cool, Spyderco!) including descriptions of steels. In the "exotic steels" section they describe it as not true steels and give ZDP-189 as the example. My question is, what makes it not a true steel and what others fall in this category?
Just curious. Thanks.
Click to expand...

hardheart said:
Perhaps because ingot steels top out at 2.1% C, and then the iron/carbon alloy is called cast iron.
Click to expand...

Bingo. "Steel", by strict definition, has a carbon content less than 2.1%.

However, taking into account that I am not a metallurgist, it is my opinion that this strict definition applies to straight carbon steel. Once some of the carbon is in the form of chromium carbide or vanadium carbide, it has a different effect and the resulting alloy is still "steel".

I especially don't think it applies to PM alloys. The PM process allows the existence of alloys whose composition cannot be made using a melt alloy process.

mete is a metallurgist. Perhaps he can confirm these opinions.
 
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