Author: Larrin
What a Good Heat Treatment Can and Cannot Do
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The Legend of Heat Treatment
There is some debate about knives that have steel with a “good heat treatment” vs those that have a bad or sub-par heat treatment. Some knifemakers have a near legendary reputation for their excellent heat treatments. What exactly is possible in terms of heat treating? How much better can steel be? How bad can it get?
H1 Steel – How it Works
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Austenitic Stainless Steels
At its most basic, H1 is an austenitic stainless steel. Austenitic stainless steels are about as old as stainless steel itself, being developed by German metallurgists in the approximate time period of 1909-1912. They worked on 18% Cr, 8% Ni steels which are quite similar to common austenitic stainless steels like 301, 302, and 304.
Annealing Part 2 – Temper Annealing, Cycling, and Final Properties
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I was interviewed by Shawn Houston on his Youtube channel about the micrographs article. See the video here.
Background
How Annealing of Steel Works – Subcritical vs Transformation Annealing
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Why Anneal?
There are three primary goals of annealing steel:
- Make the steel machinable so that it can be easily cut, drilled, and ground.
- Setup the steel for austenitizing and quenching (hardening) so that is has good heat treating response
- Provide the best possible properties in the final heat treated product
The above goals are not always 100% compatible, but we would like to offer the optimal combination based on our priorities. However, to know what the trade-offs are we need to know how annealing works first.
The History of 3V, Cru-Wear, and Z-Tuff Steel
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Thanks to Kenneth Pinnow for talking to me about 3V steel development, Gary Maddock for talking to me about PD#1, CD#1, PD#5, Z-Wear, and Z-Tuff, and Mark Zalesky and Clay Aalders for getting me a scan of a 1979 Knife World article about Vasco Wear.
New Micrographs of 42 Knife Steels
10/15/2020: I added M398, WFN, Nitrobe 77, and Vancron
2/24/2020: I added 420HC, CPM-T15, Rex 76, S125V, SPY27, and Z-Max/Rex 86
2/10/2020: I added 26C3, 1.2442, 1.2519, 1.2562, Blue Super, V-Toku 2, and A8 Mod.
How to Pick the Best Steel for Every Knife
Update 2/19/2021: In the recommendations section I updated a few of my recommendations based on new experiments and new steels.
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How to Heat Treat 52100
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52100 Steel
I previously wrote about the history and properties of 52100 in this article. The steel has been around since 1905, has been known as 52100 since 1919, and has been used in knives since at least the 1940’s. It was developed for bearings and its common use in bearings meant it has been a ready source for knife steel for decades. It is known for its fine carbide size and good toughness. The chromium addition compared with the chromium-free 1095 means that it has somewhat higher hardenability so it is easier to harden in oil and obtain full hardness. The chromium also helps keep the carbide size small. The chromium also shifts up the temperatures required for hardening.
New Steel Bohler M398 – The New King of Edge Retention?
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M398 Steel
Edit 11/19/2020: Since the release of this article I have experimentally evaluated M398, which you can read about here.
Which Steels are Easiest (and Most Difficult) to Forge?
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Forging Steel
Typically forging bladesmiths have restricted their steel selection to low alloy steels like 1095, 1084, 5160, 52100, O1, etc. There are a variety of reasons given for why the bladesmiths usually use these relatively simple steels. Often “ease in heat treatment” is a common one. However, this article will focus on which steels are physically more difficult to deform with the hammer and which crack most readily. What controls “forgeability” or steel?
