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:

So referring to steels as “super steel” or the category of “super steels” is at least as old as still-existent knife forums on the internet. Reading through the descriptions of “super steel” now and for as long as bladeforums has existed, they are typically defined as one or more of the following [1][2][3][4]:

1. New (relatively)
2. Excellent edge retention
3. Difficult to sharpen
4. Stainless

Not all of those qualities are universally used. Sometimes non-stainless steels such as 3V or Infi have been called “super steels” [4]. I am not sure if a steel must have high edge retention to be called super but in general the “new” steels that come out have high wear resistance and edge retention. Super steels are often described as having high edge retention but greater difficulty in sharpening, however. Different steels slowly lose the title of “super” over time. In the early bladeforums era, VG-10 was sometimes called a “super steel” [5] but I don’t see it called super much anymore [6]. This confirms the “new” part of the definition. I’m not sure why edge retention or wear resistance became synonymous with super rather than other properties like toughness, but this is where we have ended up.

Pre-Internet History

Unfortunately, searching through magazines and books that predate the internet is not as easy as searching through bladeforums. However, I did find one reference from Outdoor Oklahoma 1978, where a very modern sounding description of “super steel” is found:

“Some hunters are a bit reluctant to opt for super steels because these have a reputation for being hard to sharpen. It’s true, good edge holding qualities go hand in glove with hard steels and hard sharpening. Some steels, especially stainless…”

And that’s where my free view through Google Books ends. Reading through the descriptions of super steels on bladeforums I find similar descriptions to this day. In 1978 basically none of the current “super steels” were even in existence, meaning that the article was likely referring to 154CM, 440C, or both as super steels. Those steels are not called “super” any more which again confirms that steels tend to lose their super title over time. 

Edit 6/27/2022: I found an even earlier reference to the term “super steel” though the above quotes are still great because they reflect a similar mentality to today. This new reference I found is from the first issue of The American Blade Magazine (now Blade Magazine) from 1973 in an article by John Wootters called “Blades for Game”: “In this day of super-steels, there is no reason why a hunting knife shouldn’t have a hollow-ground blade. Such a grind offers less drag in meat-slicing and is easy to keep razor-sharp. the higher the hollow-grind bevel lies on the blade, however, the less “spine” or strength the blade will have, and the less abuse the knife can be expected to stand. If the steel is not absolutely top quality, however, a flat bevel offers more resistance to edge-chipping.”

The second issue of American Blade Magazine in an interview with Ted Dowell mentions that “He is still field testing the new ‘super stainless,’ 154-CM, and remains unconvinced although he offers it as an option to those who want it.”

Is “Super” a Positive or Negative?

Even in that 1978 article it was stated that some don’t want super steels because of difficulty in sharpening. The sometimes negative connotation of super steels as being nothing more than a “flavor of the month” or being too difficult to sharpen continues to this day. Therefore, it is not clear to me if the term super steel was originally coined as a negative or positive description. Many discussions on bladeforums about super steels continue to be about whether we need the so-called super steels or whether the old classics are good enough or even superior [7][8][9].

Current Views of Super Steels

While many decry the super steels as being unnecessary, the conflation of “high wear resistance” and super, or premium steel, continues. For example, in the Knife Informer article rating knife steels [10], the steels are categorized from “Super Premium” down to “Low End” with the differentiating property being edge retention. See this article for more information on articles that rate and rank steels. Because these steels are viewed as being superior, they are often perceived as also having high toughness despite their high wear resistance. In the linked article on steel ratings I pointed out that M390 is often given high scores for toughness despite Bohler not providing any toughness data on the steel. Toughness testing here at Knife Steel Nerds has also found unspectacular toughness values for M390, though it has only been tested at relatively high hardness:

The reason why almost any steel will have relatively low toughness that is designed for very high wear resistance is the large amount of carbide that is present in the microstructure. You can read more about the effect of carbides on toughness in the article I wrote on microchipping and in the summary of edge stability theory. For example, comparing AEB-L/13C26 to 154CM, CPM-154, and S30V, you can see a stark difference in carbide volume (grey particles):

13C26

154CM

CPM-154

S30V

You can see that while the powder metallurgy process greatly reduces the size of the carbides in 154CM, it does not affect the amount of carbide. While smaller carbides do help with limiting crack initiation, toughness is still reduced by having a large volume of carbide. That can be seen with charts from both Uddeholm [11] and Crucible [12]. The Uddeholm chart shows three different carbide contents along with the change in toughness with hardness; the three steels are Vanadis 4 Extra, Vanadis 8, and Vanadis 60. The Crucible chart shows the change in toughness from carbide volume when each steel is heat treated to approximately 60 Rc. 

Steels like 3V and Vanadis 4 Extra get their combination of wear resistance and toughness by having a relatively small volume of carbide (<10%) but having all of those carbides be the very hard vanadium carbide. However, the majority of the current “super steels” have much more carbide than that, as summarized in the following table [13][14][15][16][17]:

This effect of high carbide content on toughness cannot be overcome with powder metallurgy, as shown in the charts by Crucible and Uddeholm, which show both conventional and powder metallurgy steels. This means that many of these “super steels” have inherently low toughness and therefore have difficulty with impact applications or in handling high stresses in thin edges. While a steel with a small volume of carbide can also have poor toughness, carbide volume can be thought of as setting an upper bound for potential toughness of a steel. None of the current “super” stainless steels have less than 10% carbide volume, and most are 15% and up. I would like to see one of the major steel companies develop a lower carbide volume powder metallurgy stainless steel so that it is more balanced in terms of toughness and wear resistance rather than focusing primarily on wear resistance. 

Sharpenability

It is not possible to design steels that have both high wear resistance and ease in sharpening. Sharpening is essentially the intentional wearing of the edge, and therefore high wear resistance “super steels” have poor sharpenability. There are other factors that affect sharpening, of course, such as burr formation and edge geometry. However, in comparisons based on wear resistance the “super steels” have poor sharpenability. Furthermore, the hard vanadium carbides in many of the steels are harder than common abrasives like aluminum oxide (alumina) which further increases the difficulty in sharpening [18]:

Summary and Conclusions

The term “super steel” has been around since at least the 70’s and it has been used both positively and negatively as far back as I can find. The steels that are grouped into the “super steel” category has changed over time. The modern high wear resistance steels are excellent at having high slicing edge retention. Powder metallurgy and modern steel design offer “okay” or “good” toughness, high edge retention, and high corrosion resistance. However, as has been known for many decades this also leads to difficulty in sharpening. Furthermore, many steels not called “super” have much greater toughness which is important for certain applications. I don’t like the categorization of steels into “super” or “premium” down to “budget.” Different steels offer a set of properties and costs for different uses and markets. There has been pushback against “super steels” since the term originated, but I don’t think there is any reason to either ignore super steels or to claim that other steels are superior. It’s better to understand the different types of steels and what they offer. Maxamet and 1095 both have their place.

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[1] https://www.bladeforums.com/threads/define-super-steel.1186464/

[2] https://www.bladeforums.com/threads/what-does-super-steel-mean-to-you.884896/

[3] https://www.bladeforums.com/threads/super-steels.1271032/

[4] https://www.bladeforums.com/threads/what-are-the-super-steels-infi-cpm3v-what-else.1002492/

[5] https://www.bladeforums.com/threads/aus8a-steel.259612/#post-2162599

[6] https://www.bladeforums.com/threads/whatever-happened-to-vg-10.1158041/#post-13246157

[7] https://www.bladeforums.com/threads/are-you-over-super-steels.1312791/

[8] https://www.bladeforums.com/threads/super-steels-and-do-we-really-need-them.1539089/

[9] https://www.bladeforums.com/threads/super-steels-whats-the-point.959854/

[10] http://knifeinformer.com/discovering-the-best-knife-steel/

[11] https://www.uddeholm.com/files/PB_Uddeholm_vanadis_4_extra_english.pdf

[12] Pinnow, Kenneth E., and William Stasko. “Wear resistant, powder metallurgy cold work tool steel articles having high impact toughness and a method for producing the same.” U.S. Patent 5,830,287, issued November 3, 1998.

[13] https://www.crucible.com/PDFs%5CDataSheets2010%5CdsS35VNrev12010.pdf

[14]  Pinnow, Kenneth E., William Stasko, and John Hauser. “Corrosion resistant, high vanadium, powder metallurgy tool steel articles with improved metal to metal wear resistance and a method for producing the same.” U.S. Patent 5,936,169, issued August 10, 1999.

[15] Shen, Weijun, Bo Nan, Weilin Wang, Linping Yu, Qiankun Zhang, Yuehui He, Xiaolin Huang, and Guozhu Yuan. “In situ synthesis and strengthening of ultra high-carbon martensitic stainless steels in addition of LaB6.” Journal of Alloys and Compounds 738 (2018): 363-371.

[16] Almström, Linda, and Camilla Söderström. “Alternative materials for high-temperature and high-pressure valves.” (2010).

[17] Gornik, Christian, and Jochen Perko. “Comprehensive wear study on powder metallurgical steels for the plastics industry, especially injection moulding machines.” In Materials science forum, vol. 534, pp. 657-660. Trans Tech Publications, 2007.

[18] Theisen, W. “Hartphasen in Hartlegierungen und Hartverbundstoffe.” (1998).