Author: Larrin

Corrosion Resistance, Super Steels

ZDP-189 and Cowry-X – Super Steel or Overrated?

Larrin

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ZDP-189 and Cowry-X

ZDP-189 is a steel produced by Hitachi and Cowry-X is produced by Daido. I have not been able to find much background information on the development of these steels. Sal Glesser of Spyderco reported he first heard about ZDP-189 around the year 2000 [1], and the earliest reference I have found to Cowry-X on Bladeforums in 2001 [2]. So both of the steels have been around for some time. The fact that two companies released essentially the same product perhaps indicates that the steel was not patented, which means little information would be available about its development. Both steels have an interesting composition with 3% carbon and 20% chromium along with a few other small additions. There are a few different reported compositions for ZDP-189 in terms of the Mo, V, and W content but below is from Spyderco. read more

History - Articles - Books, Super Steels

Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained

Larrin

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Super Hard High Speed Steels

The super hard high speed steels (>68 Rc or so) are interesting from the standpoint of knife enthusiasts and knifemakers, particularly since knives are so often produced in the 58-61 Rc range. The metallurgy of these types of steels is also interesting. But before we get to what exactly these steels are and how they work, it makes sense to look at what led to their development first. read more

Edge Retention

CATRA Tests of M390 Knives

Larrin

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CATRA Testing of M390 Knives

Recently two sets of CATRA studies of M390 knives have been reported. One was conducted by Mike Latham of CollectorKnives, and the other by a group of people including Clint of the Alchemy_1 Youtube channel. These reports are the product of a minor controversy over the Rockwell hardness of production knives and the relation between Rockwell hardness and edge retention. Here are links to both reports: read more

Heat Treating and Processing, Nitrogen-alloyed, Toughness

Nitro-V – Its Properties and How to Heat Treat It

Larrin

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Nitro-V Steel

Nitro-V is a stainless steel sold by New Jersey Steel Baron which was first released in 2017 [1]. The steel was designed and produced in collaboration with Buderus Steel as a version of Uddeholm AEB-L modified with nitrogen and vanadium. Another obvious comparison is with 14C28N which was designed as a version of 13C26 modified for improved corrosion resistance. 13C26 is nearly identical to AEB-L but produced by Sandvik. You can read more about the history of AEB-L, 13C26, and 14C28N in this article. read more

Hardenability, History - Articles - Books

O1 Steel – History, Properties, and How to Heat Treat

Larrin

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O1 Steel History

O1 steel was developed in 1905 by Halcomb steel which was acquired by Crucible Steel a few years later [1][2]. However, the history is a bit more interesting than that. In 1876 a large Sheffield steel company, Sanderson Brothers, purchased Sweet’s Manufacturing Company’s Geddes Steel Works in Syracuse New York. American tariffs had led to a large reduction in exported steel from Sheffield, and steel output from the USA had also greatly increased to match. So several English steel companies setup production facilities in the US, including Sanderson Brothers. Sanderson Brothers was a very old Sheffield steel company, founded in 1776. Tool Steel development began to explode starting in about 1900 due to the recent discovery of “high speed steel” which you can read about here: The History of the First Tool Steel. The year 1900 was doubly significant because in that year there was a major consolidation of 13 of the major steel plants which used “crucible” steel production methods, accounting for 95% of the crucible steel production in the United States. read more