Steel Types
52100
While this carbon steel is a mainstay of the knife making world today, it was originally formulated for the manufacture of bearing components. When I returned to the US from Japan about 10 years ago, there was a handful of smiths using it for blade making. They reported exceptionally fine grain structures and astonishing edge retention so I decided to try it out. At first I tried heat treatments that others were discussing around that time, which included things like triple quenching the blades. This resulted in a very fine grain structure and high wear resistance but I disliked the glassy feel of the steel when cutting and sharpening. So I continued to experiment with heat treatments until I arrived at a process that produced a blade with a slightly toothier feel, more reminiscent of Japanese White steel, while still having improved edge retention. These blades have a hardness of ~62 HRC and I find they strike a good balance between wear-resistance and sharpenability.
It is important to note that this is not a stainless steel. It will tarnish and stain over time even when well cared for, and it requires the user to be mindful of oxidation and potential interactions with acidic foods. But the patina that develops is also beautiful in its own way and the cutting feel (切味) of carbon steel is subtly compelling.
AEB-L
This stainless steel was developed for razor blades and while that makes it an obvious candidate for knives, it was until recently very hard to find in sections thick enough for forged blades. Now that it is available, I am excited to offer a stainless version of my Kurouchi style blades. This steel contains very fine carbides which give it excellent edge forming properties. Not surprisingly, its freshly sharpened performance is like a razor. It has good edge retention but compared to carbon steel, the “used” condition is a little glassy and slick. But, it touches up quickly on a fine stone.
This is a fully stainless steel with a very smart formulation for excellent corrosion resistance. It will not interact with foods or build up a patina with time. However, because I leave a darkened section of hammer texture, that gray area is not “passivated” and can form small spots of tarnish. I recommend towel drying after washing (this is a best for the wooden handle anyway) and a little blade oil can be used to help protect the hammer textured section of the blade. But, if spots do form, they are very superficial and can usually be removed with a small amount of household cleaning powder or silver polish.