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Edge retention testing is continuing, we have now tested 18 different steels, and four of those steels with multiple heat treatments. Come to Patreon if you want updates on testing as it is completed.
Thanks to Mikolai Kawai and Tyyreaun for becoming Knife Steel Nerds Patreon supporters!
I have now published two CATRA edge retention testing updates to Patreon for those that want a preview of testing before a full article will eventually be written.
Thanks to A.N. Nash, Matt Collingwood, Noah Cowan, James Pierce, and Jay Caponetti for becoming Knife Steel Nerds Patreon supporters!
I have a new CATRA edge retention testing machine. I will be posting results as they come in to Patreon and articles summarizing the tests will come later to this website. If you want to see tests as they are completed come join us on Patreon.
Thanks to Dinkma, Gavel John, and Roger Rozenberg for becoming Knife Steel Nerds Patreon supporters!
Low-Alloy Steel Testing
Over the past two years or so we have tested the toughness of many knife steels using a simple charpy impact test. You can read about the specifications of the test on this page. With the samples tested in this article I got a lot of help from Warren Krywko and Devin Thomas as well as donated steel from Alpha Knife Supply, Barmond Special Steels, and Achim Wirtz. This article focuses on the toughness testing performed on “low alloy” and carbon steels that are often used by forging bladesmiths. It is possible to forge high alloy steels, of course, though it does not appear to be very common even today.
Thanks to Keith Coleman, Paul Bruno, Lotiel Vardamir, and Lennart Palkovits for becoming Knife Steel Nerds Patreon supporters!
Friction Forged Knives
The company DiamondBlade Knives produces knives with friction stir processed (FSP) edges [1]. Diamondblade Knives is a sub-company of Knives of Alaska. They use conventional D2 tool steel and process the edge so that it has hardness of around 65-69 Rc and a spine at 38-42 Rc. The knives are advertised as having a finer grain structure than powder metallurgy stainless steel and superior edge retention, toughness, and sharpness than knives tested in 12 other blade steels including S90V. And that the friction forged edge is stainless unlike conventionally processed D2. So I am going to detail the process used to produce the knives and what the properties of the steel likely are.
Thanks to ShavedAlpaca, giorgi chubinidze, and Сергей Якунин for becoming Knife Steel Nerds Patreon supporters!
Update 3/10/2020: We did a range of experiments with SPY27 to supplement the estimates in this article. You can read those experiments here.
Thanks to Konstantinos Noulis, Neil MacEachern, and J Kane Searcy for becoming Knife Steel Nerds Patreon supporters!
S35VN Steel History
S35VN is a steel developed and produced by Crucible Industries, released in 2009. The steel was developed by Maria Sawford as a modification of S30V by reducing the vanadium content, adding 0.5% niobium, and removing the nitrogen addition (incidental nitrogen is still present). Powder metallurgy steels typically have at least 0.03% nitrogen [1][2]. These changes led to a steel with improved toughness and machinability relative to S30V at the cost of some edge retention. Heat treatment response and corrosion resistance remained approximately the same as S30V. More information on the history leading up to S35VN can be seen in this article on the newer S45VN.
