Darrel Ralph outfits his assisted-opening DDR Gun Hammer 3-D Alpha in a 3.95-inch blade of stainless damascus with a Stellite 6K core by Chad Nichols. The frame is Nichols 3-D-carved Moku-Ti titanium damascus. Ralph’s list price: $3,500. (knife photo courtesy of Darrel Ralph)
Some of today’s alternative blade materials may change the way you look at knives
By Pat Covert
TO MOST KNIFE ENTHUSIASTS, THE WORD STEELis so closely associated with blades it would be hard to describe a knife without it. After all, since its earliest known production about 4,000 years ago, in one form or another steel has ruled the roost not only in cutlery but so many other things that pervade our lives.
Simply put, steel is everywhere. Unfortunately, most versions of it rust.
Progressive thinking in the knife arena has led to a boom in the technological aspects of blades, which includes those of materials that do not rust or rust very little in comparison to stainless steel. (Stainless steel resists corrosion but is not impervious to it.) In the process, cobalt-based alloys such as Stellite®, Talonite and Cobalt Dendritic have received attention. Other materials such as laminates using titanium and carbon fiber, as well as ceramics, also have been used to good effect.
Frost on a Windowpane
Not a common metal, most of the world’s cobalt is mined in the Republic of the Congo. Today, most cobalt is used in corrosion-resistant “super alloys,” which are particularly suited for gas turbine and jet aircraft engines.
David Boye has been making knives for over 40 years. He offers fixed blades and folders for use around saltwater and other rust-inducing environments. He has used dendritic material exclusively since 1980 because he says he prefers its strength, cutting performance, ease of sharpening, and ability to cast roughly to shape.
(Editor’s Note: For a better understanding of forging various metals into blades, check out The Complete Bladesmith: Forging Your Way to Perfection, pictured at left.)
“Dendritic is the kind of pattern [damask] which naturally forms when a carbon alloy cools after smeltering,” Boye explains. “It looks like frost on a windowpane.”
According to many knifemakers, the finer the blade’s grain structure, the better it cuts. Boye supports the opposite view.
“These relatively large, rooted and fully bonded carbides produce microscopic teeth along the cutting edge, and this is what actually does the cutting,” he notes. The combined attributes of extreme cutting performance, no rusting in seawater and being non-magnetic so it does not affect a compass or electronics make the material ideal for the ocean environment. “We have used dendritic cobalt for over 15 years and have received virtually zero chips, broken blades or complaints,” Boye says, “and many customers have raved to me about the blade performance.”
He states that the material’s downside is each knife design requires a set of porcelain molds which are challenging and/or expensive to make, the mold created for each individual blade has to be discarded after only one use, the casting alloy is costly, and the waiting time for blades from the foundry can be lengthy.
Chad Nichols is a large supplier of damascus to the cutlery industry and has pioneered a new blend of patterned steel using cobalt 6K, commonly known as Stellite, and stainless steel—particularly AEB-L and 304. “The interesting thing about the 6K cored steel is that the cobalt alloy itself does not have to be heat treated to retain edge-hold abilities,” he observes. “The only reason the material needs to be heat treated is for corrosion resistance [for the stainless steels in the damascus] and for etching purposes.”
Nichols outlined several attributes of the hybrid damascus, “The addition of the cobalt-based alloy increases its durability and oxidation resistance,” he states. “The cutting performance of the 6K damascus is great. It’s a workhorse of a steel for cutting and can retain a razor edge even under the most vigorous conditions.” As for the disadvantages of the material, there are two. “The blade material is expensive. You already have a relatively high cost for the damascus and then you add the 6K which, pound for pound, costs more than the handmade damascus,” Nichols says, adding, “It’s not a lot of fun to make, either!”
“Won’t Crack Under Flex”
The book on modern laminate blades using metal bonded to synthetics was co-authored by knifemaker Warren Thomas (also, see page 114, August 2011 BLADE®). He indicates he began making laminate blades in 1991 using stainless steel and carbon fiber. Shortly thereafter he substituted titanium for steel, creating a lightweight, zero-magnetic knife. Thomas says he uses a “trade-secret” chemical bond that positively adheres the two materials.
“My laminates have half the weight of a steel blade, absolute zero corrosion, won’t crack under flex, and don’t micro-fracture under heavy stress along the cutting edge like steel blades do,” he explains. “To improve the performance of the blade, I weld tungsten carbide along the cutting surface to enhance the edge retention. This gives it a toothy edge that improves the cutting performance.
“There is no chance of corrosion using carbon fiber and titanium. Both materials are impervious to common destructive forces like sea salts, body sweat, and other elements that wreak havoc on steel,” he notes. “Steel knives have a very hard time cutting some synthetics, such as Kevlar™. My knives actually cut these materials quite well due to their ability to saw through them.”
Laminated blades do have their disadvantages. “In very rare circumstances, the blade can delaminate. I’ve had this happen approximately a dozen times in 20 years and have always corrected the problem for the customer,” he says. “Due to the direct cost of the state-of-the-art materials involved and the time spent fabricating the laminates, there is a higher cost for my blade over steel. However, you get what you pay for.”
That’s Edge Retention!
Ceramic blades are made by taking zirconium oxide—also known as zirconia—powder, compacting it under intense pressure, and heating it in blanks at high temperatures in the 1,400° Celsius range. The blades are much more common among kitchen knives, and for good reason. For straightforward slicing and dicing they are extremely effective, but for lateral blade movement with torque, such as for prying, they tend to snap or shatter.
Boker Knives has never shied away from thinking outside the box, and its ceramic knife line not only includes kitchen knives but tactical and everyday carries as well. “If used as intended, ceramic blades will outperform steel,” Boker USA CEO Dan Weidner says. “In an independent lab test performed comparing ceramic to steel, technicians measured the amount of pressure required to cut through a standard piece of cardboard. After 1200 cuts the pressure required to cut using the ceramic blade was the same as the first cut, while the identical task using a steel blade showed decline after 400 cuts.” Now that’sedge retention!
Ceramic blades also have other benefits over stainless steel, including corrosion resistance. “This is one of the prime advantages of ceramic,” Weidner opines. “It cannot rust, which is why it’s used so often in maritime and military saltwater environments.”
There is also good news on the economic front. “Initially the cost of ceramics was on the high side, but now there are sufficient manufacturers producing the material to put the price point in the same range as good, quality steel,” Weidner says. Moreover, ceramic blades are non-magnetic.
Is One For You?
The strange brews in blade technology are not for everyone, but they offer a wide range of features, including either no rust or a huge reduction of same, zero magnetism, weight reduction and enhanced edge holding. Granted, there are downsides in some instances, though apparently not enough to discourage enough buyers of the blade brews outlined herein.
Is there an alternative blade in your future?
For more on alternative blade materials such as Spyderco’s H1, Strider Knives’ Nitinol, and Bohler-Uddeholm’s Vanax 35 and 75, see page 68 of the April 2011 BLADE®.
Also be sure to check out BLADE’s Guide to Making Knives.
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