Author: Larrin

Heat Treating and Processing, Steel and Knife Properties, Super Steels

Friction Forged Knives – Diamondblade Friction Stir Processing

Larrin

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Friction Forged Knives

The company DiamondBlade Knives produces knives with friction stir processed (FSP) edges [1]. Diamondblade Knives is a sub-company of Knives of Alaska. They use conventional D2 tool steel and process the edge so that it has hardness of around 65-69 Rc and a spine at 38-42 Rc. The knives are advertised as having a finer grain structure than powder metallurgy stainless steel and superior edge retention, toughness, and sharpness than knives tested in 12 other blade steels including S90V. And that the friction forged edge is stainless unlike conventionally processed D2. So I am going to detail the process used to produce the knives and what the properties of the steel likely are. read more

Heat Treating and Processing, History - Articles - Books, Steel and Knife Properties

S35VN Steel – Properties and How to Heat Treat

Larrin

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S35VN Steel History

S35VN is a steel developed and produced by Crucible Industries, released in 2009. The steel was developed by Maria Sawford as a modification of S30V by reducing the vanadium content, adding 0.5% niobium, and removing the nitrogen addition (incidental nitrogen is still present). Powder metallurgy steels typically have at least 0.03% nitrogen [1][2]. These changes led to a steel with improved toughness and machinability relative to S30V at the cost of some edge retention. Heat treatment response and corrosion resistance remained approximately the same as S30V. More information on the history leading up to S35VN can be seen in this article on the newer S45VN. read more

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