What is the hardest steel known to humankind? The short answer is Nitinol, also known as Ni-Ti-Nol. It’s no surprise custom knifemakers (and collectors) find it so desirable, but not always for that novelty alone. Nitonol has the ability to be heat treated to produce brilliant colors.
The History of Nitinol
Nitinol, also referred to as “Ni-Ti-Nol,” was first discovered back in 1959 by scientists William Buehler and Frederic Wang at the Naval Ordnance Laboratory. The Ni-Ti-Nol acronym stands for “Nickel-Titanium-Naval Ordnance Laboratory.”
Beuhler and Wang were searching for a super-elastic alloy for missile nose cones that would be pliable at extreme heat, yet return to its original shape after cooling. Their efforts were a success, but because the incredibly tough alloy was so difficult to process and machine, it wasn’t used until much later.
Knifemaking Discovers Nitinol a Half-Century Later
Custom knifemaker Duane Dwyer of Strider Knives became interested in Nitinol back in 2005 while searching for a super hard metal alloy that would not rust. He approached metallurgist and friend Scott Devanna, vice president of technology at SB Specialty Metals, and inquired about the possibility of producing Nitinol using the particle metallurgy process, which had never been done.
Shortly afterwards Devanna introduced Dwyer to Eric Bono, a metallurgist and knifemaker who also had an interest in the alloy, and the three men began to explore the possibilities of incorporating the alloy into knives.
Nitinol Becomes SM-100 (HIPTiNite)
With his metallurgical knowledge and experience, Bono developed a working, powdered metal version of the alloy in 2006, which the partners dubbed “SM-100.” It took several more years to refine the alloy and processes, and in 2009, Bono and business partner Fred Yolton formed a company, Summit Metals LLC, to produce SM-100.
Since that time, SM-100 (60 percent nickel and 40 percent titanium), which the company markets under the name “HIPTiNite,” has garnered interest not only in the knife industry, but also by NASA and the Formula 1 racing industry.
Properties of SM-100
The SM-100 brand of Nitinol, like its forerunner, is extremely tough. While a typical sanding belt can be used to grind several typical, mono-steel knife blades, it requires several belts, in many cases six or more, for the same process using the SM-100 alloy.
Made and sold in small quantities, the cost of SM-100 isn’t cheap. Add to that the cost of belts and additional time to shape and grind the material, and the cost per knife skyrockets.
On the positive side, SM-100 is noncorrosive, and while stainless steel will rust, Devanna says you can throw an SM-100 knife into saltwater for 50 years without the steel corroding.
An Explosion of Coloring
Bono discovered during his development of SM-100 that it can be heat colored into an exquisite rainbow of colors. Due to the titanium content, SM-100 oxidizes into a blaze of bright hues just like other alloys incorporating titanium, but the process of achieving the color effects is quite different.
Bono confides that the magic happens during the heat-treating process, in which he allows small pockets of air to leak onto the surface of the knife. Prior to heat treating, the blades are wrapped in foil and small holes are punched into the wrapping.
When heat treated, different colors occur depending on the oxygen content of certain areas of the blade steel as the surface oxidizes. The end result is the explosion of color on the SM-100 blades.
The price for bright, eye-popping colors doesn’t come cheap, but then new innovations rarely do.
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