This is the biggest project I have ever worked on, spending many, many hours to write the comprehensive tale about steel and knives. If you have ever wanted to learn more about the inner workings of the knife industry, this book is for you. Wherever possible I used firsthand accounts from metallurgists and knifemakers to explain why they innovated and how. I will give links to buy so they aren’t lost on the page and then I will explain more:
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K390 Video
Here is the video version of the following information:
What is K390?
K390 was developed as an alternative to Crucible’s CPM-10V, which has had success since the late 1970s as a steel with very high wear resistance yet also moderate toughness. CPM-10V achieved these properties by having a relatively high volume of vanadium carbides, very hard carbides that contribute greatly to wear resistance. Because the carbides are so hard, it requires less of them for a certain level of wear resistance. Carbides are brittle, so having a lower volume of carbide for the same wear resistance means greater toughness. The patent application for K390 was submitted in Austria by Bohler in 2002 [1], and the steel was announced in 2004 [2]. The main modifications to CPM-10V were increased Mo, W, and Co. This gives K390 better “secondary hardening” and therefore “hot hardness” so that it can maintain its hardness at high temperatures. The higher Mo also gives it greater “hardenability” so that large dies can still harden all the way through.
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Intro
Juha Perttula has a doctorate in metallurgy and he has published several studies in scientific journals on heat treating knife steels. So for this article I want to feature not just an individual study but a person’s work. His studies have focused on traditional bladesmithing, low alloy and carbon steels, and wootz Damascus. He also makes and sells knives which you can read about at his website, juhaperttula.com. Juha’s website also has links to the articles I will be discussing below, and I recommend you read them in addition to my commentary.
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Video
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YouTube Video
The video version of the following information is available here:
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What is ApexUltra?
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I also have some Patreon-exclusive bonus content related to this article such as Nitrobe 77, Nitro-V, and 14C28N steel hardness data and experiments on the effects of the high temperature temper on nitrogen steel hardness.
