Below I have shown the measured P, S, and O: The P and S of each steel is very similar, in fact Uddeholm Elmax has the highest levels of both of those elements. Showing representative images is somewhat difficult because there is a statistical distribution of inclusions. They also use argon gas stirring to maintain a consistent temperature. “Cold-work tool steel article.” U.S. Patent 7,615,123, issued November 10, 2009. Another interesting difference is the higher Co content in the Bohler-Uddeholm steels, and the relatively high tungsten content in Elmax which is not an intentional addition according to the datasheet. However, another manufacturer of tool steel is Carpenter, known for grades like XHP, B75P, and 204P. Become a patron and gain access to awesome rewards including early access to articles or a Knife Steel Nerds mug! https://www.patreon.com/Knifesteelnerds, Click to share on Twitter (Opens in new window), Click to share on Facebook (Opens in new window). What sets the 556-1 apart is the CPM-20Vsteel alloy which you wonât find on any of the previous Griptilian models. On the surface, the blade itself looks identical to that found on the original models. However, this comparison illustrates that B-U steels do not necessarily have superior toughness. Crucible began to sell the steel as CPM-20CV after Latrobe was purchased. This translates to +- 150 cuts per meter of rope. When the oxides are larger than the carbides then the easiest point for crack initiation is the oxide rather than the carbides. 20CV NožíÅské oceli - ocele Nabídka kvalitních znaÄkových nožů. Erasteel around 2006 began advertising a further reduction in inclusion content through a process called “Dvalin” but very unhelpfully they never say what that process is, just that it exists and makes the steel better. CPM-20CV is Crucibleâs version of Bohlerâs popular M390 steel which also influenced Carpenter to copycat with CTS-204P. The impurity and inclusion content is not going to affect edge retention, after all. The PM process combined with the high chromium content imparts M390 / CPM 20CV with good grindability and excellent polishability. The M390 knife steel is identical to the CPM 20CV or the CTS-204P in comparison of hardness(62HRC). On a chemical level there are a couple types of steel that closely resemble M390. For the light use you describe either would perform well for you. What it is: CPM 20CV is a "Crucible Particle Metallurgy" stainless steel, widely regarded as a "super steel" for its properties and performance. M390 / CPM 20CV is a PM stainless steel that offers good wear resistance with excellent corrosion resistance through the use of high chromium and vanadium content. When Bohler-Uddeholm is comparing with the “1st generation” they are usually referencing Crucible Steel. The PM process combined with the high chromium content imparts M390 / CPM 20CV with good grindability and excellent polishability. The difference in technology has to do with the “tundish” that the liquid steel is poured into prior to atomization. 1, pp. After atomization, the two carbide types (vanadium and chromium) are similar in size, but during the HIP and forging processes the chromium carbides coarsen more rapidly than vanadium carbides. Here are the compositions of each steel as provided by the manufacturer: We measured S and O with LECO combustion testing and other elements including phosphorous with optical emission spectroscopy (OES). We want the content of each of those elements to be as low as possible. However, the image does not appear in that particular document so I’m not sure where it came from. There are differences in oxygen, however. [10] Pinnow, Kenneth E., William Stasko, and John Hauser. Crucible CPM-4V. Conclusion While reviewing this steel, I felt like I m reviewing another âSuper Steelâ while reading peopleâs opinions on forums and comments on youtube videos, most users are happy with their K390. #3 Hangman, Oct 10, 2015. Sulfides are usually present in the form of manganese sulfide, as manganese is added intentionally to avoid iron sulfides. Carbon steel: Most Japanese knives will fall under this first category. There are also unintentional “impurity” levels of many elements, and some may be higher because of the use of recycled steel, such as nickel which is usually present around 0.2% in recycled steel. Some of the major claims about differences in powder metallurgy production are related to impurities and inclusions, so we need to briefly introduce what those are before explaining further. CoS M2 M390 ⦠M390 and CPM154 aren't even in the same class, M390 is vastly superior. This higher Co and W content may mean than Bohler-Uddeholm is using some percentage of recycled high speed steels that Carpenter and Crucible are avoiding.”, Elmax had the *lowest* tungsten content according to the table, at 0.20%. The heating of the tundish with electrodes allows the longer process to take place for the finer powder. The rapid cooling to produce powder rather than slow cooling to form an ingot leads to less segregation of alloy in the steel and a finer microstructure. Erasteel also has the facilities for producing powder under vacuum for specialty metals like titanium, but because of the higher cost and smaller batches this does not seem to have ever been used for knife steels that I have seen. For only The Spyderco Smock is a high performance collaboration model based on Kevin Smock's custom SK23 design. Rather than pouring liquid steel into a mold and letting it slowly cool, the liquid is passed through a gas spray which rapidly solidifies small particles, creating a steel powder. M390. It may be that the occasional larger inclusions show up more frequently in the Crucible and Carpenter steels though I did not look at such a large area as what B-U reportedly observed. You can read about different carbide types in this article. Overall itâs a popular choice thanks to its high wear and corrosion resistance, itâs premium steel and because of that its a great pick for high end or limited-edition knives. Thus, its wear and tear resistant, its corrosion resistant and its tough metal. [7] Kajinic, Alojz, and Andrzej L. Wojcieszynski. Iron sulfides melt at relatively low temperature, leading to liquid sulfides at forging temperatures, which makes hot rolling steel likely to fail. The B-U process also directly encapsulates the powder for the HIP process to avoid effects of handling powder, since sand and other impurities can end up in the powder, and the high surface area powder is prone to oxidation. Chromium carbides (M7C3 and M23C6) and molybdenum/tungsten carbides (M6C) coarsen the fastest, and vanadium carbides (MC) coarsen much more slowly. Your discussion of trace tungsten content contradicts the values in the table: “the relatively high tungsten content in Elmax which is not an intentional addition according to the datasheet. The chromium carbides are grey and the black carbides are MC (vanadium); the chromium carbides are larger than than the vanadium carbides. When you produce a larger knife you need a type of steel that is a lot tougher, something M390 simply does not excel at. Bohler-Uddeholm and Erasteel also reportedly produce a finer powder size but this does not result in a significant change in carbide size because the limitation in carbide size is coarsening during processing rather than the size of the structure in the powder. In comparisons between various products there does not seem to be much difference in carbide size between different companies. These values are about in line with expectation, as Bohler-Uddeholm attempts to restrict their oxygen content to below 0.01% [8], and values for oxygen in Crucible patents also hover around the 0.015% value [9]. European PM Conference Proceedings, vol. The m390 0562cf's are more expensive than the 204p version because they're more rare. There are only a few hundred of the m390 0562s out there. We have done a couple comparisons between the toughness of similar steels from different manufacturers, such as Bohler M390 and Crucible 20CV. Sign up for our newsletter here. Erasteel’s process is called “2nd generation” by Bohler-Uddeholm. ãã«ç¤¾ãéçºããé«çç´ ç²æ«ã¹ãã³ã¬ã¹é¼ãä¸2ã£ã½ãé¿ããããã§ããw. This may be because of the very low number of larger oxide inclusions, even in the Crucible steel. The powder is then placed into a canister for “hot isostatic pressing” (HIP) where the steel is heated to high temperature under pressure to create a solid ingot. This concise book, written specifically for knife makers in an easy-to-understand format includes tool steel properties, alloying elements, data sheets, heat treating and so much more. But thanks for looking with me. I've just never actually used s90v so I wastn't sure. High speed steels are more likely to be alloyed with Co and W. However, the amount of those elements probably has little effect on the final properties.