Various alloying elements (chromium, vanadium, phosphorous, manganese, molybdenum, nitrogen, etc.) used in blade steel, particularly in the family of corrosion-resistant “stainless,” produce certain desirable properties (edge retention, hardness, corrosion resistance, impact strength, etc.). One of the most exotic alloying elements is Cobalt, which is known to increase hardness and strength, as well as intensifying the effects of other elements in a particular steel formulation.
As an individual element, Cobalt is not found as a native metal. This element is usually found in the form of ore. As such, it is not mined alone but is produced as a byproduct of nickel and copper mining. There are many applications for Cobalt, including use in what can be termed “superalloys,” such as those used in gas turbine aircraft engines, high-speed steels and corrosion- and wear-resistant alloys. In blade steels, Cobalt is one of the components of ATS-55, CPM 125V, VG-10 and one of the very latest steel developments N690 (also known as N690Co and N690BO).
Adding Cobalt To The Mix
Bohler, an Austrian steel manufacturer, is the current source for N690. This firm is considered a worldwide leader in their production of rolled sheets and plates that offer superior uniformity. The chemical composition of N690 is as follows: carbon 1.07%, chromium 17%, cobalt 1.5%, manganese .40%, molybdenum 1.10%, silicon .40% and vanadium .10%. Typically, N690 is hardened to a factor of Rc 58-60. Obviously, the key here is the addition of cobalt in the steel matrix. The cobalt allows the creation of a very uniform structure within the steel. And when used in blade steel, this provides a fine and consistent edge, enhancing edge retention and sharpening receptivity.
In discussion with various knife makers who have had experience with N690, some liken it to a sophisticated 440C with better edge holding and stain resistance. Other makers regard the steel as somewhat similar to VG-10 and see little difference between the two. One comment that ran through all of my conversations was the fact that the steel is extremely fine grain. When it comes to edge holding, every maker agreed that the finer the steel grain the better.
Who’s Using N690
There are several production cutlery firms using N690 in their knife lines. Boker USA is offering a professional hunting and outdoor fixed-blade, designed by German maker Armin Stutz, in this new steel. Fox lists their USMC Predator fixed-blade, in camo and black, with both tanto and Bowie blade patterns in N690. The Ontario Knife Company offers their Retribution-1 folder with a liner-locking mechanism and linen Micarta handle scales in the steel. TOPS Knives has a couple of models in N690, including their COT Magnum 711 Tactical folder, featuring a tanto blade pattern and G10 handle scales. TOPS also provides this blade steel in their mid-size CQT Thunder Hawk folder that features a Teflon-coated, tanto pattern blade. And Spyderco utilizes N690 in their Jerry Hossom-designed line of large fixed-blade outdoor knives, including the Forester, Forager, Woodland and Dayhiker. The only thing limiting the use of N690 would be simple economics—material cost and availability.
I had an opportunity to use a Boker Savannah fixed-blade, which features a full tang blade crafted from N690. This knife was designed in response to Armin Stutz’s hunting experiences in Africa. The drop-point pattern blade itself is impressive, measuring 5 inches in length and featuring an attractive two-tone finish. The Micarta handle scales are elaborately grooved in an alternating pattern to provide an enhanced grip surface. Stainless steel bolsters, with a red fiber underlay and a lanyard hole at the end of the handle, complete the package.
On two successive hunting trips for wild pigs, the knife was used for field dressing and skinning chores. I found that the edge-holding ability of N690 was superior to most stainless formulations, even when working around bone. After use, I touched up the edge with a diamond rod and discovered an uncommon uniformity to steel. It would seem that the addition of Cobalt to an already outstanding steel formulation provides that extra edge that all of us are looking for.
For more information on the Savannah knife, contact: Boker USA, 303-462-0662, www.bokerusa.com.
Various alloying elements (chromium, vanadium, phosphorous, manganese, molybdenum, nitrogen, etc.) used in blade steel, particularly…
by Tactical Life / Mar 20, 2009