Hi Digger, found this on the web:
Few know what AEB-L steel is, and those that do, only have heard that it is similar to 440B or 440A. The only similarities between AEB-L and 440B or 440A is the amount of carbon. The fact that AEB-L has only 12.8% chromium by weight compared to the 16-17% in 440A and 440B makes the steels quite different. AEB-L is more similar to a stainless 52100 than 440A. A copy of AEB-L called 13C26 is made by Sandvik.
AEB-L was designed for razors, which need corrosion resistance, high hardness, and very acute edges. AEB-L has excellent corrosion resistance, in the same area as 440C or other popular stainless steels used in knives today, even though it only has 12.8% chromium. The lower carbon means much of the chromium is in solution after heat treatment. It gets very hard, up to 64 as quenched. Though AEB-L is not a powder metallurgy steel, it contains very tiny carbides, its average carbide size is six-tenths of one micron, powder metallurgy steels such as CPM-154 have a carbide size of 2-4 microns and larger. This carbide size is comparable to the finest carbon steels. 52100 has about the same carbide size. This shows why it makes such a good razor steel. Carbides are very hard particles that make a steel wear resistant. They also reduce toughness. For this reason they need to be as small as possible to offer good toughness and the ability to take and hold an acute edge while also increasing wear resistance. AEB-L's small carbides give it excellent toughness, great ease of sharpening, ease in grinding and polishing, good wear resistance, and a very keen edge to a knife. 440C has some carbides as large 50 microns. A very keen edge is about one half of one micron, so when cutting, carbide pullout happens with large carbides, the carbides are pulled like a tooth out of the blade, this makes for a toothy and hard to sharpen edge, and of course after the carbides are removed they can no longer help with cutting.AEB-L naturally forms what is called the K2 carbide, the harder of the two chromium carbides, compared to the K1 carbide, which is formed in steels such as 440C. The K2 carbide is about 79 on the Rockwell C scale, compared to 72 for the K1 carbide. Through proper heat treatment, AEB-L has fine, evenly distributed K2 carbides. AEB-L lies almost perfectly on what is called the “Carbon Saturation Line”, which means that all of the carbides formed are precipitated carbides, not primary carbides like are formed in 440C, and there is more carbon and a similar amount chromium in solution as compared to 440C. Primary carbides are very large. So, through a balanced composition, AEB-L has excellent toughness, edge retention, workability, ease of sharpening, and ease of polishing.
AEB-L vs common American carbon steels
Roman Landes and John Verhoeven have both done different tests with AEB-L. In CATRA testing Dr. Verhoeven found AEB-L to outcut 52100, 1086, and Wootz damascus. He also found AEB-L to be able to take a smaller edge radius than 52100 in controlled sharpening tests. Roman Landes found AEB-L to have greater edge stability, toughness, and wear resistance than 52100. Edge stability is a property that describes a steel's ability to hold a finely sharpened edge. 52100 is one of the most well respected carbon steels, and is well known for its small carbides, high toughness, and high edge stability, so it's impressive that AEB-L was able to beat it in these categories, while also having greater wear resistance and being a stainless steel. Many users have reported that AEB-L sharpens as easily as any other carbon steel they have used.
AEB-L vs common Japanese carbon steels
The White and Blue steels are used by many Japanese bladesmiths. They typically have a high percentage of carbon. They are given this high percentage of carbon so that high hardness can be obtained even with insufficient soak times and temperatures during heat treatment, which can be common when heat treating with equipment that is not computer controlled. The extra carbon also creates extra carbides for greater wear resistance. However, there are two major problems with these steels, especially the very high carbon Blue Super and White #1: low toughness and excess retained austenite. The low toughness comes from the excess carbon, which means that "plate martensite" is formed, which is prone to cracks in the micro-structure, even before the steel is used. These are not visible to the naked eye. The other problem is retained austenite. The more carbon is used in a steel the more retained austenite is formed. This can be reduced through cryogenic processing, but most Japanese bladesmiths don't use cryo. Retained austenite decreases overall hardness, edge stability, wear resistance, and increases wire edge formation. AEB-L also has smaller carbides than either of these steels for greater edge stability and toughness. Many users have reported that AEB-L sharpens as easily as any other carbon steel they have used. For these reasons we prefer AEB-L.