New West Knifeworks recipe for fine steel.
Whether you are baking bread or making a chef knife, you need to start out with good ingredients.
The two fundamental ingredients of steel are iron and carbon. Specifically, the combination of the elements must fall between .2% and 2.14% carbon to iron. Bear in mind that the slight variation in carbon content and heat treatment creates steels of extraordinary variety, from ball bearings, jet engine blades, automobile trim, or a chef knife.
The evolution of steel is inextricably linked with the advance of civilization, as evidenced by the fact that we actually refer to the ages of history as "the stone age, Bronze age, iron age, etc." We could call our current age the "alloyed-steel age".
The early history of steel is primarily that of carbon steel. Indeed, carbon steel knives (knives made almost entirely of iron and carbon) are extraordinarily sharp and can take a wicked edge. The problem with these knives can be that iron tends to form bonds with oxygen - a process we know as rust. A carbon steel knife will have a patina on the blade, as the iron on the surface forms bonds with the air. If you don't mind a little brown on your chef knife, (or as some argue, a slight metalic taste to your food!) this may not seem like a big deal. The real problem is that as the blade begins to oxidize it can actually distort the crystalline structure of the molecules on the edge of your knife, bending the edge. (Requiring the edge be "honed" or bent back into shape). So, carbon steel chef knives, as awesome as they can be, do require a good deal of care to function in their optimal state.
Luckily, human knowledge grows with history. Humanity has learned how to build cars, fly planes, and even walk on the moon. All of these advances have made our knowledge of steel more sophisticated. All you need to make bread is flour, yeast and water. But there's a lot more you can add depending on what flavor you are looking for. The same is true with a chef knife. The discovery and understanding of the chemical properties of different elements has exponentially increased our knowledge of metallurgy, allowing us a level of sophistication unimaginable even a century ago.
The point of all of all this is that we've come a long way since burly bearded blacksmiths and the iron age. In some ways, the industrial revolution was a revolution in making super steels. Every industry has unique requirements for precision machinery in every possible environment imaginable- from deep sea exploration, to the precise mechanics of the Hubble Space telescope operating in the cold vacuum of space, to the rigorous specs of a nuclear reactor. The benefit for the home or pro chef is that we can borrow the most beneficial properties of all these processes to make chef knives of an unprecedented quality.
The key to these advances is the special alloys (elements) added to the basic carbon/iron recipe for steel.
Iron and Carbon
The steel we use for all of our chef knife edges is called 154 CM. You start out with iron. Add .85 carbon. Remember .5% is already considered high carbon, so that's a generous amount of carbon. In fact, our 8- inch chef knife has a proportion of iron to carbon 70% higher than a comparable Wusthof trident. This means it is a harder chef knife and can take a sharper edge.
Chromium (the stainless element)
Stainless steel is any steel that has more than 13% chromium. The Chromium prevents oxidization. Unfortunately, for a long time, the added Chromium hindered some of the properties which made a great chef knife (think of your extraordinarily stainless, but dull butter knife.) However, by adding some other alloys, like Molybdenum or Manganese you can alter the grain structure in ways that make up for whatever is lost by the Chromium. The result is what are known as High Carbon Stainless Steels, or "alloyed steel". This is the kind of steel New West Knifeworks uses in its chef knives. We believe you can have your cake and eat it too (without getting rust on your knife from the icing!) We use 13-14.5% Chromium. 13% is the cut off for stainless rating. So, you still want to dry them, they're NOT stainless steel butter knives.
Where Chromium prevents rust, Molybdenum prevents other forms of corrosion. It also provides toughness to the blade at high and low temperatures. These properties make it common in industrial processes and functions like the steel used for Arctic oil pipelines, it is also becoming standard for automotive trim to ensure long life, even along a sea coast or after continued exposure to de icing salts.
A dash of Manganese helps remove sulphur and Oxygen from the molten iron. It makes steel easier to form and work with. It also adds to the strength and toughness of the blade. Railroad tracks, for example, use steel with Manganese in it. A low sulphur content is essential for a high quality machine tool as excess sulphur can make the blade brittle. Manganese combines with sulphur to neutralize its effects. It has been discovered that the steel used to make the Titanic had high sulpher content (the frigid waters of the North Atlantic made the hull extremely brittle.) All steel has some amount of sulphur in it, A8 falls on the extremely low sulphur end of the spectrum.
In very small amounts Phosporous aids strength and corrosion resistance. Like Sulphur, a steel's quality is measured by how little of this substance remains in the blade from the smelting process. Like sulphur, New West knives have very little Phosphorous.
Nickel is alloyed with steel to make armor plate, vaults and machine parts. AUS 8 uses .49% Nickel to take advantage of its strengthening properties.
Silicon Carbide is nearly as hard as diamond. By alloying the chef knife with silicon it helps the steel undergo the extreme transitions of the heat treatment process or tempering the knife undergoes to strengthen its grain structure.
Tungsten is alloyed with steel to form tough metals that are stable at high temps. This is important during its tempering process. High tungsten steel is used for things like high speed cutting tools, drill bits, and rocket engine nozzles.
Our last alloy, Vanadium has several beneficial properties. Its corrosion resistance makes it useful for making special tubes and pipes for the chemical industry. It also provides shock resistance which is why it is alloyed with steels used for axles, crank shafts, gears for cars, and jet engine parts.
The secret ingredient: Heat Treating the Steel
Stick the chef knife in the oven at 910° Celsius….
So, we've gathered the best ingredients we can find, and that guarantees we have the best bread, right? No. Not yet. It all depends on how you bake it, and the same is true with a chef knife.
You can have a low quality steel and put it through a precise tempering process (heating and cooling) and it will perform better than a chef knife made with better ingredients treated poorly.
At room temperature, iron stabilizes in molecular grain structures known as body centered cubic. This means the structure of the grains, the molecules, form Cube shaped lattice bonds. In this state the softish metal can dissolve only a little bit of carbon (carbon is the key to hardness, remember.)
Bear in mind that iron very rarely exists in nature in its pure elemental state. You will not find it lying around in the crust of the Earth. Iron atoms tend to form bonds with either sulphur in the form of iron pyrite (fool's gold) or with oxygen in the process known as "oxidization", or rust. So, in order to get some pure iron, the iron composite material needs to be heated to a high enough temperature to destroy the oxygen or sulphur bonds. Then you've got pure iron . Then, when the pure molten iron is heated to 910 C the grain structure undergoes what's known as a phase transition. (When water goes from liquid to steam or liquid to ice, this is a phase transition.) The iron transforms from its Body-centered cubic molecular crystal structure to what is known as Face Centered Cubic, which means the atoms in the molecules share even more common points in their interconnecting lattices. (The electrons intersect not only at corner positions where the atoms meet, but also along the "face" of the cubic structure, and even in the voluminous space of the cube.)
Also, at this temperature, the iron can dissolve more carbon. This is important because we want the iron to bond with carbon as opposed to oxygen or sulpher. Now, if the molten iron were to slowly cool, it would begin to bond with oxygen, and the Face-centered cubic structure would revert back to the softer structure. To prevent this, the material is suddenly cooled or quenched so that there is no time for it to go back to its previous state. (Henkels advertises there "ice quenching" technique as making there blades stronger. All fine steels use some form of "quenching." New West uses temperatures much, much colder than ice to "quench" its chef knives.)
The result is a new material where the grains are very tight at a lower temperature. You've made an extremely hard steel. However, it is still brittle. It needs to be heated to a medium heat to destroy some of the newly formed crystal structures. The result is a chef knife that is extremely hard but also tough.
As you can imagine this process involves real alchemy. Every minute adjustment creates variations in the resulting chef knife. So, this is where the craftsmanship and art come in to play. At the highest level, as in anything, it comes down to taste. Do you want your chef knife superhard even though it won't be easy to sharpen? Or to take a sharp edge but not hold it as well?
The Axis of Steels - Japan and Germany
Traditionally speaking, German knives have tended to be softer, tougher steels that can take more abuse than a Japanese chef knife. The Japanese knives, however, hold more carbon and therefore are sharper and retain a better edge than their German counterparts. The difference undoubtedly derived from the diets and tastes of these very different peoples. In addition to the regular vegetable chopping and slicing jobs, a German chef knife may often be used as a small cleaver- hacking through bones and joints. The Japanese diet, centering around fish, demanded a precision chef knife handled with finesse and incredible skill.
The Best of Both Worlds
In modern times, both the Japanese and the German styles borrow from one another. New West Knifeworks strives to find the balance between these two styles- the toughness of the German chef knife with the sharpness and edge holding of the Japanese. Furthermore, all of our knives and steel are 100% American Made and we take advantage of the technological advances in metallurgy developed for the US aerospace and defense industries.
Specifically we use powder metal steel. CPM S35VN, a steel that optimizes taking a razor sharp edge, holds it well, is extremely tough and is easy to sharpen.
New West knives have a hardness rating of 60-61 on the HRC scale. Read more about Powder Metal Steel!