Category: Carbides
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.
Testing the Edge Retention of 48 Knife Steels
Thanks to Trevor Welch, Theo N, Guns N’ Loaded, EV.Knives, Erik Coccia, Francisco J. Neto, Tristan, Gareth Chen, Alvise Miotti Bettanini, Henjie Taguinod, ben horridge, Steven, and Ian Miller for becoming Knife Steel Nerds Patreon supporters!
M390 vs 20CV vs 204P – 3rd Generation Powder Metallurgy Technology?
Thanks to Josh Warren and Alex K for becoming Knife Steel Nerds Patreon supporters!
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.
Carbide Types in Knife Steels
Thanks to Todd Kroenlein and David for becoming Knife Steel Nerds Patreon supporters!
Cementite
The most basic carbide type in steel is an intermetallic compound formed between iron and carbon, commonly called cementite. Carbides are hard and brittle, similar to a ceramic material. Cementite has a relatively complex structure but in its simplest form it is 3 iron atoms for every carbon atom: Fe3C. However, other elements can partially replace the iron, so the carbide is sometimes given as M3C where M can mean Fe, Mn, Cr, etc. Cementite is typically present as either particles or in “pearlite.” I introduced what pearlite is in this article. However, cementite is the only carbide type that typically forms in pearlite, so to keep things simple for this article I will be focusing on carbide particles. Below I have a schematic representation of carbides (black circles) along with the grain boundaries (black lines).