WHY A DUNN KNIFE HOLDS ITS EDGE
LONGER THAN ANY OTHER KNIFE.

For several years, I have been debating with myself about whether I should try to explain to you – my customers, and in many cases, my friends – the technical reasons why my steel and my knives are superior to others. Part of my internal debate was about not boring you, and part was whether you would understand the technical parts. I think that I was underestimating you – my friends and customers – and for that I apologize. And now, I will try to explain in both laymen’s terms and some technical jargon what has happened to steelmaking over the last thirty years.

Conventional steelmaking begins by melting all of the alloys going into specific steel; i.e. carbon, molybdenum, chromium, silicon, vanadium, and the list goes on according to what the end-use of the steel will be. The melting is done in a large electric arc furnace.

This is typically followed by a second refining process during which the slag or any other impurities are removed, after which the molten metal is poured from the furnace into molds and formed into ingots. While the alloys in the molten steel are uniformly distributed (homogeneous), as the ingots cools, the various elements segregate, resulting in a non-uniform microstructure. Even though further mill processing breaks up and refines this microstructure, the separation effects are never completely eliminated. The higher the alloy and carbon content, the more detrimental are the effects of the segregation on the finished steel product – in this case, knife blades.

In recent years, steel manufacturers have developed a particle/powdered metal process which eliminates the separation/striation of the steel’s alloy components. This particle metal process also begins with a homogenous molten mixture, but instead of being poured into ingot molds, the molten metal is forced under extremely high pressure through a small nozzle where high pressure gas breaks up the liquid stream into a spray of tiny, round droplets. These quickly become solid and collect as powder particles; this powder is relatively spherical in shape and uniform in composition. Each particle is essentially a miniature ingot which has solidified so rapidly that separation of alloys has been almost totally eliminated. The carbides which do form during the solidification are extremely minute because of the rapid cooling and the tiny size of each particle.

Now the powder is screened and loaded into steel containers which are pressurized to remove all the oxygen and then sealed. The containers are then reheated to approximately the same temperature used in forging, but this time under extreme pressure; this is known as hot-isostatically pressed (HIP). The extreme pressure used bonds the powder into a fully dense compact. The resultant microstructure is extremely fine-grained and homogeneous, and in the high-carbon and vanadium steels which we use exhibits a uniform distribution of minute carbides. These compacts are then processed using the same standard milling procedures for conventionally melted ingots, but the powdered metal steel has improved toughness, little or no segregation of the alloys, and thus offers much higher performance than the old-fashioned method.

Up until a few years ago, only custom knife makers, and very few of us, were using these superior-quality steels to make our knives. Several of the mass-production knife companies attempted using these steels for a short period of time. Most of them have pretty much discontinued using the higher-end powdered metal steels because of the toughness. The problem they all had was that they had to continually replace the grinders in their computerized milling machines. Of course, we who make custom knives and use the steel already knew that these superior powdered metal steels were really rough on abrasives. What the mass manufacturers requested of the foundries was that they lower the carbon and vanadium contents in the steels they have chosen to use in order to cut down the cost of replacing their grinders.

When you read the testimonials on my website; talk to hunters, fishermen, and trappers who use my blades; and after the above discussion, I hope you will understand a little better why your Dunn Knife serves you so well.