Category: Steels

4 thoughts on “Steels”

  1. Thanks for what you are doing. There is so much misinformation, hyperbole, and exaggeration being presented as fact on the internet regarding knife blade steel. I felt like the skies cleared when I discovered your site. I really appreciate your science-based approach to demystify so many issues.

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Corrosion Resistance, Nitrogen-alloyed, Steels

Nitrogen-Alloyed Knife Steels

Larrin

Thanks to Matthew Hoffman, Tryggvi, and Ron Dillon for becoming Knife Steel Nerds Patreon supporters!

In previous posts I have written about the process by which steel is hardened. The steel is heated to a high temperature phase called austenite, where carbides are dissolved and carbon goes into solution in the austenite. During rapid quenching the carbon is trapped between the iron atoms and a phase called martensite is formed. Martensite gains its high hardness from the distortions to the atomic structure that come from carbon in between the atoms.  read more

Steel and Knife Properties, Steels

Ranking the Steel Ranking Articles

Larrin

Note: I now have a steel ratings article of my own, read it here: Knife Steels Rated by a Metallurgist

Intro

Thanks to Stacy Apelt for becoming a Knife Steel Nerds Patreon supporter! Based on a poll of Knife Steel Nerds Patreon voting members, we have decided to purchase a small impact tester for knife edges. This will allow us to study the effects of steel, heat treatment, edge geometry, sharpness, etc. on chipping and rolling of edges. read more

Damascus, History - Articles - Books, Steels

Five Myths About Damascus Steel

Larrin

Knife Steel Nerds coffee mugs have been shipped to all current “Ultimate Steel Nerd” Patreon supporters. 

What is Damascus Steel?

There are two major steel types that are called Damascus:

1. Crucible, or Wootz, steel was first produced in India and Central Asia and produced into swords anciently from at least the 3rd century AD [1]. It is made by producing small ingots of high carbon steel that are then forged and thermal cycled in a specific manner to lead to carbide bands that produce the final pattern when the steel is etched [2][3]: read more

Corrosion Resistance, History - Articles - Books, Steels

Steel History – The First Stainless Steel was for Knives

Larrin

Update 7/23/2018: I added a small piece of new information on the development of 440C steel to the article. 

Thanks to Greg Hanson for becoming a Knife Steel Nerds Patreon supporter!

The writing of this article was made much easier due to the existence of The History of Stainless Steel by Harold Cobb [1]. If you want more information on the history of stainless and the people who developed it, check out the book. read more

Corrosion Resistance, Metallurgy Principles, Steels

How Much More Chromium Does D2 Need to be Stainless?

Larrin

Thanks to Devon Craun for becoming a Knife Steel Nerds Patreon supporter! Your support is funding knife steel research. 

Some materials like aluminum form a passive oxide layer that prevents further corrosion. Steel is not one of those materials. Instead, steel forms iron oxide, or rust, that doesn’t protect the underlying iron and flakes off leading to further corrosion. However, when sufficient chromium is added then a chromium oxide passive layer forms which protects the steel from corrosion in a similar way to a metal like aluminum with its own aluminum oxide layer. A simple schematic diagram shows the passive film vs rust [1]: read more

Heat Treating and Processing, Steels, Tempering, Toughness

Toughness testing – Cru-Wear, Z-Wear, Upper vs Lower temper, Cryo vs No Cryo

Larrin

Thanks to Paul Hart and James Covington for becoming Knife Steel Nerds Patreon supporters!

I recently completed some toughness tests on samples that were heat treated by knifemaker Warren Krywko. The steel was donated by Chuck Bybee of Alpha Knife Supply. The samples are subsize unnotched charpy specimens with dimensions as specified on the bottom of this page: http://knifesteelnerds.com/how-you-can-help/ If we can get more people to make toughness specimens we can have more comparisons between steels, hardness points, heat treatment parameters, etc. Patreon dollars are for the purpose of paying for machining, shipping, testing, etc. for tests like toughness and CATRA edge retention, so if you are able to contribute that way please visit the Knife Steel Nerds Patreon page.  read more

History - Articles - Books, Steels

154CM – Development, Properties, Use in Knives, and Legacy

Larrin

Update 6/19/18: I have added new toughness numbers from a 1962 publication comparing 440C and 154CM. Go to the bottom of the article to see them. Thanks to Russ Andrews for sending me the article.

Thanks to Sal Glesser, Brian Huegel, Mark Bellou, Timothy A. Johnson, Daemon Lindenmayer, and David Olkovetsky for becoming Knife Steel Nerds Patreon supporters! We reached our goal of funding an edge retention study! read more