VG XEOS

[p_atrick]

For all of you who are smarter than me, what can we surmise based on Spyderco's analysis of VG XEOS. I realize that Spyderco is not 100% confident the numbers they posted, so we need to take the chart below with a grain of salt. I'm sure that heat treat plays a part as well, so you really can't look at numbers and predict what behavior will look like. I may not know much, but I know that this is complex stuff. Here is VG XEOS as compared to VG-10 (click on the image to see a larger version):

Can we make general statements like the reduction of carbon and the increase in chromium means that more chromium will remain in solution as compared to VG-10? What about the vanadium? There is more of it, but less carbon. I know that alloying elements "compete" with each other to bind with carbon. Is there any indication that VG XEOS could have more vanadium carbides? If vanadium remains in solution, what does that mean? Does it help in other ways?

Please feel free to point out any corrections I need to make. There are many of you here who know a lot more about this than me. Just curious about a new steel. I realize the best answers will come once the mules start shipping.

EDITED: removed hyphen from new steel's name

[Bolster]

Good questions, and may I add one...

Is VG XEOS still an ingot steel?

[Mage7]

Hmm that really seems like a pretty negligible amount of vanadium, honestly. I have a feeling that's more of a trace-element situation than an intended addition. What stands out to me is the molybdenum and tungsten, even though the tungsten is in pretty trace quantities too.

Seems similar to N690, or to ZDP-189, but with substantially less carbon. Given Spyderco's description that it is supposed to retain similar edge holding to VG10 but with increased corrosion resistance, I am thinking you're probably right that the goal was to keep more chromium in solution, but add elements to form other carbides to assist in edge holding.

Edit:

I couldn't help but remembering Larrin Thomas' page saying something about tungsten and molybdenum...

Tungsten and Molybdenum in Stainless Steels

Generally no Mo2C or Mo6C carbides are seen in stainless steels, even with high Mo additions. In 154CM and CPM-154, for example, despite the 4% Mo, only chromium-type carbides are seen, though somewhat enriched with Mo. We looked at this experimentally in scanning electron microscopy of CPM-154. However, during tempering very small Mo2C carbides form, but those are the very small tempering carbides that contribute to hardness, not the larger primary carbides that contribute to wear resistance which are the focus of this article.

Tungsten additions are not common in stainless steels, the biggest one I know of is a 0.6% addition to M390/20CV/204P steel. For the reasons discussed above, that W addition is unlikely to lead to the formation of any WC or W6C.

Then there's takefu's page on it...
https://e-tokko.com/v_gold_xeos.php?lang=en

We have developed a new grade of steel for blades that combines high corrosion resistance and high hardness at a high dimension, which had been difficult to achieve in the past, with a fine microstructure created by a special melting method that improves wear resistance, strength, and quenching properties.

So my undereducated guess is that it's trying to retain the edge holding ability of VG10 by being able to achieve higher hardness rather than being carbide-rich.

[weeping minora]

It looks like an attempt to create a finer microstructure and add extra corrosion resistance to the VG-10 "class" of steels, with the goal of achieving an elevated balance of properties. This could mean greater edge stability and toughness in use, along with greater corrosion resistance when compared to VG-10.

Vanadium is included in such small amounts to control grain growth and to keep the carbide size "in check" (small). VC will still be present within the steel at this amount of addition, it just won't behave like you expect out of a steel like 10V. I'm surprised that no one mentioned the addition of Niobium within the steel. Even in such a trace amount, Nb will contribute to forming very hard, very fine carbides.

As a side note, I find it interesting that manufacturers seem to be taking a step back in refining steels that aren't dominant in one or two aspects, but rather equalized as a whole, creating very balanced steels. I believe the buzz of Magnacut may have paved the way for a new rat race to create the greatest, most well balanced steel.

[Librarian]

Can we make general statements like the reduction of carbon and the increase in chromium means that more chromium will remain in solution as compared to VG-10?

Yes.

What about the vanadium? There is more of it, but less carbon. I know that alloying elements "compete" with each other to bind with carbon. Is there any indication that VG XEOS could have more vanadium carbides? If vanadium remains in solution, what does that mean? Does it help in other ways?

With this amount of vanadium, it does not form vanadium carbides. Vanadium dissolves in chromium carbides. Some of the vanadium will be in the iron matrix, some will remain in chromium carbides. This amount of vanadium is unlikely to have much effect on wear resistance.
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If you carry out the calculation in JmatPro, you can get a funny result on the composition of the phases (after hardening the steel). If we take the average composition of elements, then steel contains a large proportion of ferrite, which is not very good.

But if you take the maximum carbon content and minimum chromium content for calculations, then everything turns out well and you can evaluate this steel. I think the last option is more like the "true composition".

For now we can make such a rough estimate. At its core, this new steel is a modification of 440A. With slightly greater corrosion and wear resistance and comparable maximum hardness.

[SchoonerBum]

I can’t speak to any of the metallurgy, but from reading the description I’m pretty excited about trying this out. VG-10 tweaked for better corrosion resistance sounds like a dream!

[Mr_Whiskerz]

I thought SPY27 was supposed to be 'reworked' VG-10?

[p_atrick]

I thought SPY27 was supposed to be 'reworked' VG-10?

SPY27 has a fair amount of cobalt like VG-10. But it has more carbon, a lot more vanadium, some niobium, etc. SPY27 is a particle steel while VG-10 is an ingot steel. See image below (click for a larger version.)

Is it possible that both SPY27 and VG XEOS started with VG-10's formula and got to very different places through the addition/subtraction of different alloying elements? Sure, but I don't have enough insider info to say one way or the other. I think SPY27 gets the "reworked" VG-10 comparison due to the cobalt. Not many steels have that much cobalt. Of course, VG XEOS has no cobalt.

[aicolainen]

I thought SPY27 was supposed to be 'reworked' VG-10?

It's very clearly stated that VG-10 was the inspiration for Spy27, but Spy27 is still a US made steel and can't replace VG-10 in any meaningful way for knives produced in Japan.
I'm not sure Xeos can do that either, but it's nice to see that there is progress and development going on with Japanese produced steels as well. I'm not a steel snob, so I'm quite OK with VG-10, but it doesn't get me very excited. And even less so when you already have a bunch. So yeah, I wouldn't mind if Spyderco's Japanese base steel was replaced at some point.

[Mr_Whiskerz]

I thought SPY27 was supposed to be 'reworked' VG-10?

It's very clearly stated that VG-10 was the inspiration for Spy27, but Spy27 is still a US made steel and can't replace VG-10 in any meaningful way for knives produced in Japan.
I'm not sure Xeos can do that either, but it's nice to see that there is progress and development going on with Japanese produced steels as well. I'm not a steel snob, so I'm quite OK with VG-10, but it doesn't get me very excited. And even less so when you already have a bunch. So yeah, I wouldn't mind if Spyderco's Japanese base steel was replaced at some point.

Ah ok, I didn't consider the location of manufacture in the SPY/VG-10 comparisons.

And I get what you're saying about VG-10. It's fine steel. Easy to sharpen, cuts beautifully, just not exciting.

[The Mastiff]

It looks sort of close to the 440A that used to be so popular for knives. Tungsten can be in there simply because the batch of steel that the numbers came from was made using recycled steel. That would be my guess as those levels it won't really do much. When recycled steel is used you can find things like copper, and weird things like cadmium at trace levels. If you order a batch of this ( or pretty much any other) steel and then a year later order more ( from a different melt by then) the numbers you get from the foundry along with the order will be different slightly . The numbers that are important to make the steel what it is will be met but you might see extra elements just there because of the recycling process. I believe steel is the most recycled product there is or it's close to it.