AUS-10 vs. AUS-8

After ordering the 4 Max Scout in AUS-10, I was thinking about what makes it different to AUS-8. According to the manufacturer Aichi, here’s the compositional difference:


Composition of the two:




For reference of the alloys, the top slot in the chart:





It has twice the Manganese, and about 30% more Carbon. The trouble is that I actually don’t quite understand how that would affect the end result performance of the steel in a knife. Do you guys know how to interpret that difference, what the hypothetical change in properties would be?

Ryan,
AUS-10 is similar to 440C if I recall correctly.

It’s a little different from 440C, having quite a bit less chromium, less molybdenum, and a small amount of vanadium. Which is different enough to make it more different from 440C than it is from AUS-8, so it’s not quite a good comparison.

Ryan,
Yeah, I have been asking the same question, and the answer I always got was that it was like 440C. Same with 9cr18. There has to be some difference, I am thinking that the 4% difference in Cr should make the Cr carbides finer and not as coarse as 440C. Metallurgy is not my strong point.

AICHI Website

The simplest way to get a comparison is to look at all the charts on the page together to get a clearer picture.

Aus8 and 10 have similar properties to 440c and 440b loosely, but with less corrosion resistance. they are going to be more like AEBL grade corrosion

10 can get a little bit harder. but the differences are so small i think most production makers are not going to be taking either to the limits

summary
the reasons to pick an 8 or 10 over a 440 grade steel is simple. do you want toughness, or corrosion resistance at the same strengths?

440 offers better corrosion, AUS better toughness at the same strength

Quote
cKc (Kyley Harris)

440 offers better corrosion, AUS better toughness at the same strength

In that case I think I’m happy to have the AUS-10 over the 440C. I think the knife is coming in the mail tomorrow, so I’ll be able to do an HRC test on it soon. Tomorrow or Friday for sure.

AUS 10 vs 8 will have higher carbide volume and wear resistance. Hardness might be a point or three higher but not a huge jump. The potential is there to be higher but it all depends on heat treatment. Given the choice I’d take AUS 8 but if I liked the design I wouldn’t worry about it. If it were a knife for rough dirty cutting like opening sand bags or something 10 might last a little longer but maybe not.

Quote
me2
Given the choice I’d take AUS 8 but if I liked the design I wouldn’t worry about it.

Agreed. I’ve always liked AUS-8A, from both Cold Steel and Al Mar (made by Moki in Japan). The Al Mar knives are a couple points harder and don’t form burs as readily as the CS knives, but in both cases they’re less likely to chip and fracture than other stainless steels I have and the knives can still be ground easily by India stones.

We have used both grades. BTW, it's AUS-8 or 8A, not both. 10A Will get harder, hold an edge better and will corrode more easily than 8A.

8A will get sharper by a small amount. we've also used AUS-8W which will cut more aggressively, but not hold it's edge as long.

sal

W for Wolfram? Sounds interesting whatever it means.

It’s probably a small tungsten addition.

Hi Me2,

Tungsten.

Just Talkin' Story:

couple of decades ago, our Seki trading partner told me that one of the Masahiro brothers made a Sashimi style knife out of AUS-8W (Tungsten added). He said that you could lay a folded piece of rice paper on the edge at the heel, blow on the paper and the knife will cut the paper in half before it reaches the tip. Naturally I said Bullsh*t.

About a week after I got home, I received a knife in the mail, a piece of rice paper and drawings showing me how to hold the knife and where to put the paper. I set the folded paper on the heel of the blade, edge up, and blew on the paper, which much to my surprize cut the paper in half before reaching the tip.

We made about 500 of them out of the AUS-8W a bit shorter than the sample, maybe 6" - 7" blade length. But it wasn't a good seller. I still use one at home.

sal

AUS-8W sounds like a good steel

I’ve often lamented the loss of availability of the F series tungsten finishing tool steels. Now I have another reason.

Chris,
Oh, yeah, I would love to have a knife in F2

Kinda of want to see a knife made out of just tungsten.

Ha, like not even tungsten carbide, but just sold tungsten?

Well they are both very brittle, I think it would come down to which is less brittle, and what sort of edge their grain structures would facilitate. But I think people salivate over tungsten carbide a bit to much.

What about these? Sandrin made quite a splash a few years ago.

Yeah, I saw that someone chipped it malting the blade through a hair clip. It looks like its about as durable as anything from Bark River Knives. Which is probably acceptable for tungsten carbide at that angle.
At 17:49


?t=1069

Looks like the video embedding could use some tweaking.



Edited 3 time(s). Last edit at 03/22/2022 10:55PM by Older Spice.

Quote
Older Spice
Yeah, I saw that someone chipped it malting the blade through a hair clip. It looks like its about as durable as anything from Bark River Knives. Which is probably acceptable for tungsten carbide at that angle.



?t=1069

Looks like the video embedding could use some tweaking.

it doesn't accept parameters like the time sequence unfortunately

Back to AUS steels - their sulfur content is quite low aichi seem to make
very clean alloys which is good sign of steel quality.
I would prefer AUS grade over 440 in production knife for simple reason:

Being less alloyed in Cr and generally cleaner than most alloys
that would result in reaching higher strength in production ht
compared to grades like 440B/1.4112 which would be closer
to these than 440C mentioned (carbide volume, toughness).
If we dont see them ht to higher strength in production knives
thats another topic but these steels are normally capable
reaching HRC on par with AEB-L in production ht which can
give consistent 62HRC for production without cryo. 63 with cryo.

Regarding the tungsten carbide - they would make sense
in a form of disposable blades for scalpels or cutters that
will be used lightly and blades disposed as only tiny fraction
of users would be able to resharpen them with good results.
They would also limit the design of the tools to avoid types
of geometries that would allow maximum cutting ability
due to manufacturing cost and low toughness to resist chiping
in the primary grind, also edge stability isnt as high
as high grade knife steels. Using sintered carbide as blade material
is rather similar to cerramic than to steel.

There were times people used forms of natural cerramic
materials and knapped vulcanic glass as cutting tools and if they
would perform better than steel knives they would never stop using these.

JS Cutting Tools
instagram.com/jscuttingtools