Blade Steel... What's the Difference??

[Firefighter880]

Hello All,

I'm wondering what the difference is in the blade steels that Spyderco uses to make their knives? I've been collecting Spyders for several years, and I've always just blindly associated higher price with higher quality steel. I don't mean that inside the spectrum of Spyderco knives, but rather when comparing something like a $10 gas station knife to a Spyderco knife... higher price=greater product.

As for the actual steel, I know relatively nothing about it. A few recent threads have made me begin to ponder this. What is the difference in the steels? I know Spyderco uses s30v, 440c, VG-10, and H1 but other than the H1, I really don't understand the differences, and why some people prefer certain steel types over others.

If someone would be so kind, please explain the differences in the steel, and why one might prefer a certain type of steel over another.

Thanks to all who reply.

[dedguy]

As best as I can understand the higher end steels that Spyderco uses have much much better edge retention, corrosion resistance and durability than cheaper knives. Often you're also paying for higher quality handle materials and just overall better craftsmanship.

I'm sure many could give much more indepth explainations.

[zenheretic]

The quest for perfect steel. That is why steel choices evolve over time. In the past, corrosion resistance, fracture resistance, ease of sharpening all vie for perfection. Increase one stat to say make a steel easy to sharpen, and other factors suffer. Make a steel to hard and it starts to chip easier and is harder to sharpen. In the last 5-10 years, major technological advances are breaking these "rules" and allowing all stats to be increased. That is how I see it; broken down in basic. (hopefully)

The next ten years will bring some amazing advances I'm guessing.

[yablanowitz]

What a can of worms to open at this time of night!

I'm not sure there is anything approaching a simple answer to that. You can study metallurgy for years and still not be certain what will work best for general purpose, there are just too many variables. The list of elements involved in steelmaking is impressive. Each will serve at least one function in making the properties of the steel, sometimes more than one.

The big trick is to balance the properties needed in the steel. That isn't easy to do, since people want easy to sharpen and good edge holding, strength and toughness, characteristics which are often at odds with each other.

That is about all I am qualified to say
I started three different explanations of some of the differences, and came to the conclusion that I don't know enough to explain them Most of my steel knowledge is from observation of what works in my hands.

[Zac]

Spyderco uses premium steels on all of their blades, and almost every steel is excellent in what I call the big 3

1) Edge retention
2) Impact Resistance
3) Corrosion Resistance

While some of my peers may not agree, I see S30V as the prime cut and balance of these 3 features as it is an amazingly impact resistant steel for a stainless steel. Spyderco hardens it so it is very impact resistant, but holds an edge as long, if not longer, than other's S30V.

When it comes down to steel, the critical factor is the heat treatment. Spyderco does an amazing job on all of their steels which is why I would take any with me.

[Firefighter880]

While some of my peers may not agree, I see S30V as the prime cut and balance of these 3 features as it is an amazingly impact resistant steel for a stainless steel. Spyderco hardens it so it is very impact resistant, but holds an edge as long, if not longer, than other's S30V.

Thanks to everyone who has replied so far... I'm starting to see it more clearly now. Zac has started to hit on what I was really getting at though... which steel fits which bill? Or which steel excels in which aspect?

That is what I was really trying to figure out... like "well, s30v works well for _____, VG-10 is good for these reasons ______, or why 440c is better for _______ than s30v is, etc, etc.

Thanks to all.

[jaislandboy]

yeah different flavors of steels is a good thing to me......like tasting different candy....like jelly bellys.....all good with different subtleties.....
but a corrosion-proof edge-holding steel blew my mind when H-1 hit the market...to me that was kinduv the holy grail for a "stainless steel"....i've never researched that X15-TN stuff and i really know nothing about it....
I like everything from 440c to Cpm-s30v to VG10 to H-1 to N690Co to BG-42 to SR-77 depending on the application of course.....

oh here's a link to some steel stuff:
http://www.knives.com/engnath_steel.html

[yablanowitz]

With the additional hint, I will say that I have found that S30V and 440V hold an edge better than other steels in my applications. Those range from hard use to "YOU DID WHAT!?!?"

[Zac]

CPM-S30V was the first steel designed exclusively for knives, pioneered by Chris Reeve. It is an American steel, made by Crucible Materials Corporation in Syracuse, New York. When hardened correctly, it runs 58-60 on the Rockwell Hardness Scale with a pleasing edge retention even when sharpened on a 30 degree bevel, sports an impact resistance far superior to 154CM, D2, and 440C, has amazing pitting resistance, and is relatively easy to sharpen. While some people have reported issues with chipping, when hardened to a 59 HRC, this steel does not have this issue unless abused badly. Some people claim S30V is not impact resistant, but realistically, Strider abuse tests show how impact resistant properly made S30V steel is. Additionally, Spyderco, Strider, Chris Reeve, and many other top makers use this on their true tactical models. This steel is not cheap and if it would not do the job, something else would be used. While obviously not as impact as high grade tool steels, it is one of the, possibly the most, impact resistant stainless steel. The major downside is that this steel is expensive as balls.

440C is the basis in which most steels are compared as for year it has, and to a degree still is, what the industry standard has been. It has good edge retention, great corrosion resistance, good impact resistance, is easy to sharpen, and relatively low cost. Chinese companies knock this steel off so many people assume 440C sucks...but a good treated 440C is good in my book any day.

CPM-440V is also known as CPM-S60V. It was really pioneered by Spyderco and sports amazing corrosion resistance only losing to H1. It is notoriously the hardest steel to sharpen, and is rather low on the Rockwell Hardness Scale. Still people love the edge retention so the HRC may not say everything. It is no longer produced and the only knife maker to my knowledge still using it is Microtech because Tony won't pay his steel bill, nor any other bills.

VG-10 is a Japanese steel with good all around properties. Complaints are few on this blade. It sharpens easy, holds a pleasing edge retention, has decent corrosion resistance, and buffs to a gorgeous shine.

H1 is a nitrogen based steel which does not rust, scratches easily, sharpens easily, does not chip easily, has a good edge retention and good impact resistance. Marine apps excel with this steel.

N690 is a steel I am playing more with and thanks to Spyderco and Benchmade, I have concluded this is pretty good stuff, comparing to the industry standard 440C and probably beating it out.

ATS-34 is an older 1990s steel. It has great edge retention, so/so impact resistance, and horrible corrosion resistance. I have had many rust on me. It was replaced by 154CM, the first 'official' super-steel, and 154CM has been replaced by S30V (hold Benchmade which still uses 154 extensively) which is better than either in all three elements. Oddly enough, ATS-34 has seen a market resurgence as of late, and some William Henry Knifes still use it.

ATS-55 is something toyed mainly with by Spyderco. I cannot say too much about it but it did not seem as rust prone as ATS-34. ATS-55 was replaced by VG-10.

AUS-8 is an Austrian (I believe) steel with similar properties to 440C. Some people love this, some people do not. I am in the latter as I do not find it to have edge retention anywhere near to other comparable steels. Companies usually use this on their entry level models.

ZDP-189 is a steel that has unusually amazing edge retention and it has been measured as high as a 69 HRC. While it is a cutting steel and will chip, it is not as brittle as one would presume for such a hard steel.

Not really used by Spyderco, but still important to note:

D2 is a tool steel which is seen on Randall (I think), Benchmade, Microtech, and a few others. It has an excellent edge retention, is said to have good edge retention (although I have had experiences otherwise), and is a relatively brittle steel.

A2 is a tool steel used primarily by Chris Reeve in his Hollow Handled Fixed blades. It sports edge retention slightly less than D2, less corrosion resistance, and amazing impact resistance. In theory, a fixed blade should consider impact resistance above all others. Reeve uses a coating on his blades which are one of the best in the business. The heat treating makes these blades have a great edge retention...overall, I would tell you A2 is far superior to D2.

M2/M4-high carbon tool steels made famous for their edge retention. Corrosion resistance is awful and impact resistance isn't much more. These are what one calls cutting steels.

[cobrajoe]

Very nice summary Zac, you are definately a higher class of steel junky when compared to me.

You forgot to mention the byrd steel, 8Cr13MoV. According to the source, it has similar properties to AUS-8, and from my experiences, I can't argue too much.
It does have similar edge retention and hardness, but the 8Cr(etc) steel seems to be a bit odd. I've heard stories of it resisting being sharpened on diamond rods, but it will quickly pick up an hair splitting edge when stropped on bare cardboard or using a polishing compound.

I am starting to love trying the new "flavors" of spyderco steel. (I still need to try out that wonderful H1 though)

[Gollum]

A2 is most god-awful steel I've ever used. One session in the kitchen and it's stained and pitted.
A2? Count me out!!!

[Zac]

A2 is a steel which indeed needs a coating and even then should have an element like Tuf Cloth applied occasionally...especially when exposed to elements which can be corrosive. Keep in mind the major selling point of A2 is extreme impact resistance and good edge retention. Reeve uses the KG Gun-Koteä which in my opinion is the best coating on the market. Frankly it does not show wear.

[Peter1960]

... AUS-8 is an Austrian (I believe) steel ...

I don't think so; N690Co is an Austrian steel (I'm from Austria ) and IMO AUS-8 (like AUS-6/AUS-10) is Japanese steel.

[JD Spydo]

The main difference between different types of steel are the alloys that they use to obtain different performance levels. Most of the guys have already covered the main objectives that they are trying to achieve like corrosion resistance, impact resistance, edge retention and so forth.

A lot of guys also desire a knife that is easier to sharpen. That is not an issue with me. I personally don't see how you can have a knife with great edge retention without having a blade with abrasion resistance. If a knife has great edge retention you are not going to be spending a great deal of time sharpening it anyway unless you are really subjecting it to very demanding work conditions.

There is an old adage that just rings true almost without exception>> and that being that " You pretty much get what you pay for". That is very true in the knife and cutlery arena. Also good heat treatment is also a very important determining factor. D-2 steel I have heard is not used much in production knife manufacturing because it is a steel in which heat treating is extremely critical to have it attain it's superior performance qualities. That's why most of the D-2 blades are made by custom knife makers like Bob Dozier.

[thombrogan]

S60V and S90V are die steels for plastic molds (where and why their high wear-resistance comes in and is a bonus). If S30V was really made with the knife world in mind, they also found it could please the plastic molding folks, too. So we're pleased and they're pleased. Everybody wins.

Firefighter880,

My guess is that there are two reasons why we see several steels available:

1. Affordable availability in the country of origin (8C16Cr10yamobethere in China, N690Co in Italy, VG-10 in Japan, 440C in Taiwan, S30V in USA)

2. Customer demand. We might not be able to tell you why we want a certain steel without parrotting a few people, but we want our S30V, our ZDP-189, our H1, and our VG-10 and our purchases prove it.*


*= Hoping to prove I want a martempered 52100 70/30 martensite/bainite duplex structure Schempp-designed Spyderco camp knife soon (hint!).

[John G.]

[QUOTE=Zac]CPM-S30V was the first steel designed exclusively for knives, pioneered by Chris Reeve. It is an American steel, made by Crucible Materials Corporation in Syracuse, New York. When hardened correctly, it runs 58-60 on the Rockwell Hardness Scale with a pleasing edge retention even when sharpened on a 30 degree bevel, sports an impact resistance far superior to 154CM, D2, and 440C, has amazing pitting resistance, and is relatively easy to sharpen. While some people have reported issues with chipping, when hardened to a 59 HRC, this steel does not have this issue unless abused badly. Some people claim S30V is not impact resistant, but realistically, Strider abuse tests show how impact resistant properly made S30V steel is. Additionally, Spyderco, Strider, Chris Reeve, and many other top makers use this on their true tactical models. This steel is not cheap and if it would not do the job, something else would be used. While obviously not as impact as high grade tool steels, it is one of the, possibly the most, impact resistant stainless steel. The major downside is that this steel is expensive as balls./QUOTE]

Zac,

Do you have any experience with BG-42 ? How does it compare with S30V with respect to edge retention, chipping, sharpenability, etc ?

Thanks.

[Thalestin]

John G, from my experience, BG 42 seems to be harder than s30v but seems to hold an edge better. It is difficult to sharpen. Apparently its also a very tough steel to use for knives and hence is pretty rare=)

[Zac]

Zac,

Do you have any experience with BG-42 ? How does it compare with S30V with respect to edge retention, chipping, sharpenability, etc ?

Thanks.

To my understanding, BG-42, an older ball bearing steel, was abandoned in favor of newer steels because BG-42 is amazingly hard to heat treat and obviously newer steels have more 'advantages'. I use that word because as we move along in steel technology, these advancements are no longer huge leaps, but tiny steps as they are small improvements when compared to the larger whole. I have not used one extensively but I have sharpened it and while harder than S30V, it is do-able with patience.

BG-42, IIRC, has a higher HRC rating than S30V (once again, this is all in the heat treat), slightly lower corrosion resistance, and far less impact resistance.

[shu]

Zac, I agree with most of what you wrote with a few minor exceptions:

D2 is a tool steel ..., and is a relatively brittle steel.

A "relatively brittle" tool steel seems rather contradictory to me, and is certainly not my experience. In fact, I would rate D2 up there with S30V (another favorite of mine) depending upon how I intend to use the blade.

A2 is a tool steel used primarily by Chris Reeve.... overall, I would tell you A2 is far superior to D2.

I would guess from reading this you had a problem with a D2 blade but have been happy with CRK? I would be curious as to who made the problematic knife, and whether it was poorly heat-treated or perhaps work hardened. My guess is it wasn't a Dozier, though.

Just my take, obviously YMMV.



Ff880- Regarding Spyderco blade steels, the Spydie aphorism certainly applies - "all good, just different".

[SpaceInvader]

A seldom-mentioned material favored by custom maker Koji Hara is the Japanese powdered high speed steel alloy called Cowry-Y. Curious about its composition, I once inquired with the manufacturer, Daido Steel, whose US rep provided the following compositional breakdown (compared to CPM S30V):

Steel ----- C - Cr - M - V - RC
COWRY-Y - 1.2 - 14 - 3 - 1 - 61-64
CPM S30V - 1.45 - 14 - 2 - 4 - 57-59

There is another version called Cowry-X, both alloys were developed for knives by Daido. The rep mentioned, "These materials have a very fine and uniform microstructure, distortion due to heat treatment is small and good mirror surfaces can be achieved... ":

Steel ----- C - Cr - Mo - V - HRC
COWRY-Y - 1.2 - 14 - 3 - 1 - 61-64
COWRY-X - 3 - 20 - 1 - 0.3 - 63-67