Frequently Asked Questions
A Swedish carbon steel 19C5VA, or American tool steel O1 are used in combination with nickel for high contrast or 15N20 for double high carbon performance. Swedish stainless steels AEB-L or 19C27 are used with austenitic stainless 302 or 304 for high contrast, or used with ATS-34 for double high carbon stainless. Some special combinations are offered such as D2/154CM or 3V/154CM. For our custom knives we often offer san-mai where there is a solid core steel that does the cutting with a jacket of damascus or other steel.
The average wait time for a custom order for a custom knife is 6-8 months, and damascus is variable. Of course, the wait time is only a few days for currently available products.
Mokume gane means "wood-grain metal." It refers to a diffusion bonded material of multiple non-ferrous metals. My most common combination is 3 colors with brass, copper, and nickel-silver.
AEB-L is a stip steel made in Sweden by Uddeholm.Composition:
|C||Si||Mn||max P||max S||Cr|
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 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.
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.
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.
It has been said that a poor steel with proper heat treatment is better than a super steel with poor heat treatment. This is true;however, better than both is of course a super steel with a super heat treatment. I take great pride in my heat treatment, the study of heat treatment and the pursuit of the optimum combination of properties for various types of steels and knives has been worthwhile and thrilling. I use optimized austenitizing and tempering temperatures and times along with liquid nitrogen and a multi-step process for the best combination of toughness, edge stability, hardness, and corrosion resistance, selected for each steel and application. This is done through minimizing retained austenite, grain size, and carbide size. The annealing cycle, done after forging to soften the steel, is often overlooked by knife makers. An improper anneal leads to an ugly carbide structure and a large grain size, which leads to poor toughness. Even industry annealing cycles are often developed for larger carbides because this means lower hardness for easier manufacturing. My annealing cycles are designed for smallest possible carbide size and grain size.
Sticky is the wrong word. An etched damascus blade actually helps prevent sticking, as in food tends to stick to it less often. However, the knife can be etched deeply or lightly. A deeper etch has greater contrast, and you can feel the pattern. This means that the blade has greater friction when making certain types of cuts, though it also helps prevent sticking. A light etch can be done which will cut like a "normal" finished blade;however, the contrast won't be as great. I offer both options. My typical knives don't have a really deep etch, but a pattern can be felt. In most situations a difference in friction when cutting isn't noticed with this type of finish, but a lighter etch is also available.
Nickel and 304, since they are unhardenable, will wear down faster, giving the steel a slightly "toothy" cut to it after the first initial uses. We use the minimum amount of nickel or 304 to minimize this, our steels contain only 8-11% nickel or 304, depending on the pattern. Most factory made blades don't use cryogenic processing, usually leaving 10-20% retained austenite, which is soft, in their steels. So it's important to remember that you may not notice any difference even with the damascus that does have some softer steel in it. 304/nickel added steels have the greatest contrast available. If the toothy effect is a concern, a double high carbon combination, or san-mai damascus, can be purchased instead.
In short, we don't know, though there are plenty of theories to wonder about, there has been no major testing done on damascus to find out. Any testing that has been done hasn't been extensive enough to prove anything, but there has been a very little testing done. There are many possible advantages;for example, O1 is a very wear resistant steel, while 15N20 is very tough. When O1 and 15n20 are used together, it may get a combination of toughness and wear resistance not found in either steel. There is also the possibility of increased edge retention with damascus steels. Two steels that have high edge retention with different compositions, and possibly for different compositional reasons, may have the best of both worlds when used together. A common example is the serration effect given by a softer steel with a hard one. This can be good or bad, depending on the application. Another example is our AEB-L/154CM damascus, one is a steel with very small carbides (AEB-L), and the other has large carbides (154CM). The AEB-L is going to be fine grained and have small carbides, giving it a fine, polished edge, good for certain cuts, while 154CM is convential, meaning it will have some large, bulky carbides, which generally means your knife edge is going to be slightly toothy after some cutting, even if you get a fine polish in the first place, which is good for many different cuts than those good for a polished edge. Together, you may get some of the best properties of both. We plan on doing testing on this, either with a CATRA machine or another method, though it might be difficult to show that there is an increase in performance with general testing methods. Another interesting thing about high-alloy double high carbon damascus is that the steels respond to heat treatment better after being forge welded together into damascus, meaning they get harder. This shows that there is some reduction of the carbide size, and more evenly distributed carbides, after the forging.
We are also considering providing san-mai material such as stainless laminated CPM-M4 to give some stain resistance and ease of finishing to CPM-M4. In addition to the fine/coarse combinations of AEB-L/154CM, 3V/154CM, etc. we also make coarse/coarse: D2/154CM or fine/fine: AEB-L/CPM-154 and 3V/CPM-154. In double high carbon mixes, we are limited to steels with high nickel in carbon steels (15N20), or high molybdenum in stainless steels (BG42, 154CM/ATS-34, CPM-154) to provide a bright layer for contrast. Those stainless mixes containing high molybdenum such as 154CM are not as easy to etch as those with 302, and require etching with muriatic (swimming pool acid or HCl) or sulfuric acid rather than Ferric Chloride. These high performance mixes are also limited to certain patterns, call for more information.