Category: Super Steels
7 thoughts on “Super Steels”
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Friction Forged Knives – Diamondblade Friction Stir Processing
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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.
Spyderco-Exclusive CPM SPY27 Steel Analysis
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Update 3/10/2020: We did a range of experiments with SPY27 to supplement the estimates in this article. You can read those experiments here.
ZDP-189 and Cowry-X – Super Steel or Overrated?
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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.
Super Hard (70 Rc) High Speed Steels – Maxamet, Rex 121, and More Explained
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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.
Super Steels vs Regular Knife Steels
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Super Steel
I see frequent references to “super steel” online, and I was curious about how long that terminology has been around. I did searches on bladeforums as it is one of the oldest knife forums. The number of references to “super steel” has increased over time, but so have the number of posts on bladeforums. I saw how many references to “super steel” there were in each year, and then as a proxy to how many posts there were on bladeforums I did a search for “154” and saw how many references there were each year. Google tops out at 200 results but at that point the dataset was big enough to get an idea:
Hello i kinda stumbled across your site looking for. Spyderco zdp189 metal information as I’m looking to swap to a custom set of replacement blades for my titanium scaled Byrd 8cr. 3pcs set.
A simple blade swap would be nice but, they don’t have any replacement options so started to look at making a set my self from Vg10 or S35v but have no idea if need pre heat treated steels or to cut grind the blades first then heat treat…? I’m a small hobbies guy and have had to get creative with this project, because I’m stubborn, there isn’t getting parts like most spyderco knives which annoyed me greatly so i now made it harder by trying to make custom blades and parts to retrofit.
I’m completely new to this and was just trying to make a small upgraded twist but i got dragged down a rabbit hole trying to get help. And i spoke to spyderco an they dont have plans to update the steels in the byrd line.
When you buy steel it is annealed soft for working. You have to cut and drill the blade before heat treating, though some people partially grind the bevels before heat treatment as well.
I’ve looked through your website and to say the least I’ve learned a lot about steel that I didn’t know and otherwise likely wouldn’t!
Out of curiosity what steel would you recommend that has high wear resistance and good if not really good tuffness?
Depends on how much wear resistance you need. In my recent article on Vanadis 8 I was impressed by how much of a toughness improvement it had over CPM-10V.
hi
im curious about relation between hrc and rex-121
if hrc of rex-121is below 70 edge retension will be significantly lower than over 70 hrc?
Hi I’ve been doing a lot of browsing around popular sites that sell custom knives, and comparing them to my own knives that I’ve made with a variety of high grade high carbon stainless steels, and high speed steels. Many companies claim to use the most high quality high carbon steels rather than stainless steels, and according to your knife steel ratings, there are numerous stainless steels that have a higher balance of hardness and toughness as well as corrosion resistance. If these knives they sell are home forged, I have a feeling they would be made with a carbon steel that is more forgiving when it comes to heat treatment which don’t compare to most super steels.
I read your article on vg10 and super gold steel which are very common in Japanese knives; but looking at some other high alloy stainless steels such as s35vn and s45vn, they are said to be even better. However I don’t find many people that make knives with s35vn other than fold knives. Do very many people understand the difference in quality when it comes to metallurgy?
There are a lot of factors that go into steel choice including availability. It is relatively difficult to obtain VG10 and Super Gold in the USA but easy in Japan. I’ve never tried to buy CPM steels in Japan but I imagine buying the domestic steels is easier and potentially cheaper.