N690 Stainless Steel for Knife Blades
N690 Cobalt Stainless Steel
N690 or N690Co as it is sometimes called, is a Cobalt-enriched stainless steel from Austrian steel company Bohler. N690 shares some similarities with it's other Cobalt-steel bretheren such as ATS-55 and VG-10, which are used by Spyderco. Spyderco in particular has a tendancy to use Cobalt steels in their knives a lot and uses N690 in the Spyderco Volpe.
One of the first companies to use N690 steel in their knives was Extrema Ratio, and the steel was well-received. Though not given a "super-steel" stamp, it was and is still considered an exceptional steel that performs up there with VG-10. Now N690 it mostly found in knives that are manufactured in Europe, as N690 is from Austria.
The added Cobalt improves the wear resistance and edge retention of the steel in addition to ensuring a uniform grain structure.