A group of doctors are walking down the hall of the hospital; another joins them. The original group starts discussing a patient's electrolytes. One asks the other, 'What did you think?' He replies, they were interesting, to say the least.' Another says, 'Yes, but what about the sodium?' Another replies, 'Could be artifactual, or indicative of third spacing.' Yet another says, 'but how would these electrolytes compare with a person in renal failure?' Another opines, 'the potassium would probably be higher in renal failure.'
By this time, the doctor who joined the original group has only one thing on his mind: WHAT THE F**K WERE the electrolytes??
The discussion of steels on this forum has followed this pattern; a pattern which is more likely to add to confusion than lessen it. Without stating the elemental composition of the steels in question, discussion about their relative merits is of dubious value. Certainly there is more to steel comparison than the elemental composition, but it is the essential beginning for other comparisons.
I don't know the composition of knife steels off the top of my head. Especially the new ones. I have, on the other hand, looked up these data and posted them on numerous threads regarding steel comparisons. It sure would be nice if the original poster would post the elemental compositions of the steels in question, or at least the original answerer, if the poster cannot find them.
The elemental composition data for AUS6M, Z60CDV14, AUS8, and AUS118 (aka ACUTO440) are given HERE
With these data in mind, meaningful comparisons to more familiar steels can be made. AUS118 is basically A2 with the Cr increased from 5.1% to 17.5%.
Another comparison would be AUS8 with slightly higher carbon ( 0.75% vs. 0.95% for 118), and the Mo increased ( 0.7% vs. 1.4% for 118), with more Cr (14% vs 18%).
AUS6A is also a closely related steel; with AUS118 having slightly less Mn ( 6A is 1%, 118 is 0.5%), but more C ( 0.65% vs 0.95%for 118), and slightly more Mo ( 1.2% vs. 1.4%).
D2 is another closely related steel, but with more C than AUS118 (D2 is 1.5%, 118 0.95%), less Cr ( D2 12%, 118 18%), a smidgen less Mo (D2 1.1%, 118 1.4%); the main difference is the much greater amount of vanadium in D2 (1% vs 0.2% for 118).
With these data in mind, the expected characteristics of AUS118 / ACUTO can be deduced.
A steel very similar to A2, but with more corrosion resistance, yet less toughness due to the higher Cr content of AUS118.
Parenthetically, chrome can increase the toughness of steel, but generally at low concentrations. See the Crucible site HERE . Note that M2, S5, S7 and other tough tool steels have low concentrations of Cr.
Also similar to AUS6A, but with better edge holding, due to the carbide forming effects of the higher Mo level, combined with more carbon to form carbides with.
AUS118 probably will not hold an edge as well or be as tough as D2. The higher C content and much higher V content, together with the lower Cr of D2 contribute to edge holding and toughness respectively.
So, as the sage said, 'let's define our terms.' I think that more useful discussions would be the result.
Comments, criticisms, or questions, as always, welcomed.
Be sure and check out the FAQs on the first page of BFC. Joe Talmadge has an excellent steel FAQs, in which he explains the different nomenclature, as well as the different constituants of common alloys. He gives links to a number of helpful sites.
His Spyderco site is out of date; for the correct site URL, and some sites that Joe doesn't give, see my answer to the rather ignorant poster who asked about 1050 steel, and couldn't or wouldn't bother to try and find the composition.
Despite what some users might respond (those that say "well, that's a good theory, but in reality I've used this stuff and..."), you can tell a GREAT deal about a steels' potential, when optimally heat treated, by analyzing it's alloy makeup, especially in the relatively simple (read "non supersaturated CPM type") martensitic steels.
I believe I can simplify and distill a good bit however. Chrome provides corrosion resistance, more gets more. Chrome also makes alloys brittle in knife hardness ranges when it exceeds ~15%.
It is misleading to compare things like A2 or D2 with AUS-118, VERY different steels. Both are arguably better knife steels in their own niche, especially if corrosion resistance is not an issue.
*** SUMMARY: In practice, AUS-118 is right between 440B and 440C, and is going to be a bit more corrosion resistant but also similar to AUS-10 in performance. Decent but ordinary stuff. ***
AUS-118 has very high chrome. It will be very corrosion resistant after heat treating Probably gets brittle above a working hardness of Rc58-59.
AUS-118 contains a bit of Vanadium, which 440B/C do not, and at low levels this can refine the grain structure a bit (good quality) and the potential for hardness (Vanadium carbides are very hard, Rc82-85) and response to heat treat.
AUS-118 also contains nearly twice (but still only 1.5%) the amount of Molybdenum as the 440B/C series does. Molyb produces Moly carbides (Rc72-77) and so helps increase attainable hardness, like Vanadium.
Carbides improve wear resistance, but are at low concentrations in AUS-118 so not much wear resistance benefit here.
So, AUS-118 should be a minor improvement over 440B but very similar.
AUS-118 should probably attain a similar available hardness vs. 440C (less carbon in AUS-118, but more moly & vanadium), but have a better grain structure, which may translate into slightly improved edge taking capability and overall ease of sharpening. Subtle effects both.
[This message has been edited by rdangerer (edited 03-12-2001).]