Edge Retention, Steel and Knife Properties

Can CATRA predict Rope Cutting Performance?

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CATRA Edge Retention Testing

I previously wrote articles about CATRA testing of edges. The CATRA test uses 5% silica-impregnated cardstock which it slices with a fixed stroke length and force. The first article primarily looked at the effect of edge angle on edge retention; specifically, that edge angle greatly controls edge retention: read more

Reviews

Book Review – Damascus Steel Swords: Solving the Mystery of How to Make Them

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Introduction

In July 2018 a new book was released on the research of wootz Damascus steel by Dr. John Verhoeven. Dr. Verhoeven is well known for his contributions to research on knife steels and damascus, along with frequent collaborator Al Pendray. Dr. Verhoeven has often been cited on this website, including his articles on CATRA testing of different knife steels [1], and also a series of experiments on sharpening of knives [2]. He also wrote a book on the metallurgy of knife steels, which is now published as Steel Metallurgy for the Non-Metallurgist; I reviewed it in this article on book recommendations. Dr. Verhoeven had a particularly strong impact on my interest in steel and metallurgy. I was introduced to him through his knife steel metallurgy book which I read several times in my teen years. And when I was looking for the best steel University to attend, he was the first person I emailed for advice. I asked him for an interview to be published on this website, and he asked if I would be willing to review his new book instead – Damascus Steel Swords: Solving the Mystery of How to Make Them. read more

Corrosion Resistance, Edge Retention, Sharpness

Does Acidic Food Affect Edge Retention?

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I was interviewed on the Knife Junkie Podcast, so make sure you check that out.

Acidic Food

Carbon steel knives are frequently used in kitchens, probably the majority of them made by Japanese bladesmiths and knife companies. Kitchen knives cut a variety of foods, and some of them are corrosive. There has been some debate about whether any of these potentially-corrosive foods can actually affect sharpness or edge retention of kitchen knives. Sharpness is controlled by the radius/width of the edge. You can read more in the article on sharpness vs cutting ability. read more

Corrosion Resistance

Which Knife Steels Have the Best Corrosion Resistance?

Thanks to John Scarborough and Robert Angerer for becoming Knife Steel Nerds Patreon supporters!

Corrosion Resistance of Steel

I have written about steel corrosion resistance in the past, like the article on adding chromium to D2 to make it a stainless which also talked about the effect of heat treatment on corrosion resistance. In the most basic terms, if we start with iron or a very low carbon steel and add chromium to it, the resistance to corrosion improves with increasing chromium [1]: read more

History - Articles - Books

Knife Steel Nerds 2018 in Review

Here at the beginning of 2019 I decided to write up a retrospective of Knife Steel Nerds so far. A lot of things happened in 2018. First of all, the Knife Steel Nerds website was started, with the first article being posted February 27, 2018. That first article was about a modified 3V steel developed and patented by Crucible but never sold as far as I know. Links to the website were not shared with anyone until March 8th, however. read more

Interviews

Interview with Zvi of Zknives.com

Thanks to the Knife Steel Nerds Patreon supporters for an awesome 2018!

Introduction

Zvi, who goes by Gator97 on many forums, developed the website Zknives.com which contains many articles on various topics including many on knives and sharpening. He also has a steel composition database which is the largest ever made collecting essentially any steel ever used in knives. As far as I know it is the largest database of steel compositions of any type. The database is available on his website and as Android and iOS apps. Because of that very useful contribution to knife steel nerds, I asked Zvi if he would be willing to be interviewed and he graciously agreed. read more

Steel and Knife Properties, Toughness

Why Cold Steel Is Brittle

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Effect of Temperature on Strength

Steels become stronger at lower temperatures. This can be measured with the “yield strength” which is the load to permanently deform the steel. This deformation is in the form of a shape change, ie. if you are bending steel it stays bent, when hammering hot steel it dents, when flexing an edge it rolls. This is perhaps easier to visualize for those that have forged steel because hot steel is easier to forge, and is progressively more difficult to forge as it cools down. This increase in strength at lower temperatures continues below room temperature, so steel at cryogenic temperatures is stronger than at room temperature. Here are values for yield stress for 410 stainless steel heat treated to 39 Rc [1]: read more

Cryo, Edge Retention

Cryogenic Processing of Steel Part 3 – Wear Resistance and Edge Retention

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Intro to Cryo and Wear Resistance

In Cryogenic Processing Part 1 I covered the effects of cryo on retained austenite and hardness. In Cryogenic Processing Part 2 I looked at the studies on cryo and toughness. Wear resistance is the most controversial aspect of cryogenic processing of steel. In particular there are claims that the use of cryogenic processing (liquid nitrogen) leads to an improvement in wear resistance that is not found with subzero processing (dry ice). Sometimes it is claimed that cryo can lead to massive increases in wear resistance [1]: read more