A2 210mm Gyuto
This A2 is a toothy, wear resistant alternative to my 52100. While it offers a meaningful step up in terms of stain resistance, it should still be thought of as a carbon steel blade. Moderate weight and thickness at the spine. 5.9oz (168g)
While they have not been etched or polished to bring it out, this generation of A2 has a subtle, Itamehada-like carbide banding (see the picture at bottom left). This will become more visible as the blade patinas with age. Please click the Info button below for an in-depth look at the microstructure of my first generation A2 steel.
The handle is made in Sakai, Japan from water buffalo horn and magnolia wood. Comes with a kimono-silk sleeve and cork lined blade cover (sleeve color varies).
Whenever I am developing a heat treating regimen for a steel that is new to me, I start my trials with the basic recommendations from handbooks and material data sheets. I then examine the results using my hardness tester, microscope and simple performance tests; nothing tells me more about a blade than putting it to use.
Based on these evaluations and considering basic metallurgy for the composition of that steel I do a series of tests to improve performance. This process can go on for years, as it is something that must happen in the margins while I maintain the production of other knives and run a business. I also read as much as I can about the steels I use and related principles in academic papers and patent applications.
This A2 steel is something I have been working on for just about a year. In the course of many tests I have arrived at a point where the results in terms of edge-forming seem truly excellent to me. The wear resistance is a bit higher than my 52100 but not frustrating to sharpen. Only modest gains were made in stain resistance but this is still a welcome perk .
It happens that these samples also display mild/moderate carbide banding (reminiscent of Itame-hada). This structure is brought out by the way I forge the steel and is preserved in the finished product because of the way I anneal, harden and temper. I've always been intrigued by this type of structure in blades, partly because they appear in Japanese swords and wootz steel but most of all because my teacher, Mr. Ashi, produces honyaki with very striking banded microstructures. That being said, I did not prioritize the development of banding in this steel. I would not chose it over performance, but find that I get excellent edge quality in this steel under these conditions.
Yet to some, the original recipe of the steel manufacturer should always be maintained: alloying elements should not be allowed to segregate into heterogeneous morphologies. Rather, they should be kept in or returned to solution to give a uniform distribution of carbide. It is true this approach will result in mechanical properties more consistent with the information on the data sheet. For these reasons industry regards banding as an undesirable defect. But I am open to the possibility of using steels in ways that were not intended by those who first formulated them.
I hope some of you will decide to check it out. The process of researching and improving will never end but I think this is a good and interesting place to start sharing the experience with customers. I have every confidence that these will prove to be workhorse knives capable of meeting the demands of professionals and serious home chefs.
My thoughts and opinions on carbide banding are based largely on the writings of J Verhoeven, O D Sherby, J Wadsworth, and H Föll.