Steel is the best medium for knives because it is malleable. It can be made soft or hard depending on how it is heated and cooled. It can be shaped while soft and then hardened to make a great cutting tool.
In the old days, steel was mostly just iron and carbon. There was no way to remove impurities in the raw materials. When the steel cooled, its grain structure formed randomly. You can think of the grain structure like water: cooled one way it forms snowflakes, cooled another way it forms very dense ice. In steel, dense compacted grain structure, like ice, is what you want for a cutting edge. Forging, or hammering, on the steel as it is cooled compacts the grain structure along the edge so it was its hardest and most dense.
With the advent of modern, high-carbon stainless steels, or alloy steels, forging has become obsolete. These steels were developed for the aerospace and industrial machining industry. Parts made for airplanes and space ships are made to such precise tolerances that it was impossible to forge them. Therefore, super-hard, super-dense steel that could be precision machined had to be developed. Precision machining is what is often referred to as stamped.
Modern steels are a precise mixture of many different alloys that control the structure of the steel. Different alloys cause steel to have different properties. Manganese and silicon are two key alloys that are responsible for controlling the growth of grain structure. There are many different alloys that are added to the steel to give it other beneficial qualities such as stain resistance, wear resistance and toughness.
The other step in creating a superior blade is heat-treating. Steel must be precisely heated and cooled to bring out the ideal properties of the alloys it contains. It is very much like baking bread - you can put in all the right ingredients, but if you don't let it rise enough or bake it at the wrong temperature or humidity and so on, it just does not come out right. It is the same story with steel. It must be precisely heat-treated (cooked). Cryo-treating is an additional step added to the process in which the steel is frozen to -110 degrees Fahrenheit. Studies have shown that this insures that the alloys in the steel perform at their optimal potential. It usually raises the Rockwell Hardness of the steel by one point.
Forging does not improve the edge-holding ability of a blade made out of quality, high-carbon steel because the grain density is already as tight as it can get. There is much evidence showing that forging can be detrimental to the performance of modern alloy steels. Hitting the steel as it is cooling and the alloys are doing their thing can cause micro-cracks in the grain structure. This is the reason it is common for forged high-carbon stainless steel knives to break when they are dropped. Modern high-carbon stainless alloy steels are like Aunt Esther's cherry pie crust - they are at their best when they are kneaded/handled as little as possible before they are cooked.
So when looking at knives, how do you know you are getting a good knife? There is no clear answer. One thing is for sure - fine high-carbon stainless steel is very expensive. If you buy a chef knife for $12, you aren't getting the good stuff. If you know a lot about metallurgy, you can look at the alloy composition of the steel. Otherwise ask for the recommendation of a chef or some one who has experience using and sharpening knives.
At New West Knifeworks we use a special steel which uses 'Powder Metal' technology. Basically, molten steel is sprayed through a nozzle and freezes instantaneously into a mist of fine powder. We then use extreme pressure to compress this powder into a sheet from which we laser cut the basic knife shape out of the sheet. The resulting blank is then heat treated. The powder metal process results in grain structures that are greatly superior to either traditional forging or stamping processes. To find out more about the Powder Metal process click here.
Now take a look at our knives.
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