Category: Steel and Knife Properties
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What Causes Razor Blades To Dull
Thanks to Mike Strickland, Joe Dickens, Carson Reid Davis, Kenneth, Jordan Danz, Wade Smith, Jeremy Kline, and Ryan Guldbrandsen for becoming Knife Steel Nerds Patreon supporters! I have posted initial results of experiments testing my new powder metallurgy knife steel. So come join Patreon if you want to see how the steel is doing before everyone else.
2020 in Review: Knife Steel Edition
2020 had a lot going on, of course. But a lot of good came in the area of knife steel. Let’s go through some of the highlights.
New Steels
The big announcement in terms of new steels was the Spyderco-exclusive CPM SPY27. This steel was announced in January of this year, and I offered early analysis based on the released composition here: CPM SPY27 Analysis. That wasn’t the end of my SPY27 coverage, however, as I was able to get a bar from Spyderco and Niagara Specialty Metals and perform a range of experiments on it, including hardness, corrosion resistance, toughness, and microstructure evaluation. Read the results of my experiments here: SPY27 Testing.
Steel Properties that Knifemakers Care about and Users Don’t
Thanks to Markus Stark, Nils, and Brent Stubblefield for becoming Knife Steel Nerds Patreon supporters. And Kyle Daily for increasing his contribution amount.
Knifemakers vs Users and What they Care About in Steel
Vanadis 8 – Better than CPM-10V
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My book Knife Engineering is available for Christmas and Hanukkah presents.
History of Vanadis 8
The history of Vanadis 8 goes back a lot further than just the steel itself, really we have to know the history of 10V to know all of the background that is relevant. You can read about CPM-10V in this article. CPM-10V is important because Vanadis 8 is intended as a replacement for CPM-10V, or at least for similar applications. CPM-10V was developed by Crucible in the late 70s, as the first powder metallurgy steel to utilize a microstructure made up of only vanadium carbide, as opposed to chromium and molybdenum/tungsten carbides. This gave 10V a combination of good toughness along with very high wear resistance from the ~10% vanadium and therefore ~17% vanadium carbide.
CPM-S110V Steel – History and Properties
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I’m eventually going to stop plugging my book Knife Engineering in every new article, but that day is not today. Go buy one for yourself, and everyone you know, as a Christmas present.
Lost Knife Steels – Questek Ferrium M60S
Thanks to Lukas Bell, John Miles, Miika Jussila, Johan van Zanten, Dirk Pinkerton, Robert S, and Joseph Albert Padia for becoming Knife Steel Nerds Patreon supporters!
This article has a moderate amount of background metallurgy information in it. I explain briefly the necessary background information and provide links to earlier articles with more complete explanations. However, to get a full picture of steel metallurgy and heat treating, the easiest way is to read my book Knife Engineering.
M398 Steel Testing – Edge Retention, Toughness, and More
Thanks to Joel Sunderland for becoming a Knife Steel Nerds Patreon supporter! And thanks to pog for increasing their support.
The steel ratings table from my new book Knife Engineering has now been added as a Patreon-exclusive with M398 added to the table.
What is the Future of Stainless Knife Steel Design?
Thanks to Aram Compeau, Gordon Olafson, and John Walton for becoming Knife Steel Nerds Patreon supporters! I have an update on Patreon about the “rare earth” elements in AR-RPM9 steel.
I completed a minor revision to my new book Knife Engineering to correct a few typos. Some readers outside the USA also asked for more conversions from Fahrenheit than were present originally, so I incorporated both Celsius and Fahrenheit everywhere in the book in the text and tables, though some images and charts still have only one temperature scale or the other. I wouldn’t say that the changes in the revision are big enough to buy a new one if you have it already, this is not a new edition, but if you haven’t purchased one yet this is as good a time as any.
S90V and S125V Knife Steel – History, Properties, and How to Heat Treat
Thanks to Gabe Newell, George Thorpe, Jason, Rogelio Escobedo, Wes Newman, and Wayne Sears for becoming Knife Steel Nerds Patreon supporters! On Patreon there is a new article exclusive to supporters about Artisan Cutlery’s exclusive steel AR-RPM9. The composition was recently announced so I analyzed the composition.
13 Myths about Heat Treating Knives
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General Heat Treating Myths
1. Heat Treating is the most important factor for high performance knives. This one started out along the lines of “even the best steel will perform poorly if given a bad heat treatment,” and that I can’t disagree with too much. However, it has become somewhat fashionable to talk about knife performance as entirely (or almost entirely) controlled by the knifemaker’s skill in heat treatment. This has some truth to it as knifemakers who use a subpar heat treatment will certainly have subpar performance. However, the heat treatment can only do so much. No heat treatment is capable of making high carbide CPM 15V into a high toughness steel. No heat treatment can turn 1095 carbon steel into a stainless. And I would argue that the single most important factor for knife performance is the edge geometry rather than the steel selection or heat treatment. The edge geometry greatly controls the cutting ability and edge retention of the knife and also resistance to chipping and rolling. The image below shows measured edge retention of 154CM knives with different edge angles so you can see the vast difference in measured performance (higher number means more cardstock cut). Of course, focusing on any one of these factors at the expense of the others: steel selection, heat treatment, and edge geometry, is a mistake and each should be optimized for the given knife. But if we were to pick one factor that is the “most important” I’m not sure that heat treatment would be the one.
Those photos and drawings will help people understand ! Orientation – I was curious about what Crucible does with that .Their CPM goes to Niagra Metals for rolling and they cross roll the steel. Cut into squares and rolled alternating direction to minimize directional properties. I think Matt Gregory found that in his visit.
It would be interesting to test the transverse toughness of those steels for sure.