Ranking stainless steels

J

Joe Talmadge

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Oct 3, 1998
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In the Steel FAQ thread, Jason (medusaoblongata) mentioned that the FAQ didn't really clearly answer the main question people went to the FAQ for: to understand which steel is better than which other steel. There are many problems to answering this question, but the main issue boils down to: in order to do a clear ranking of steels versus each other, it is necessary to oversimplify to the point that such rankings are badly inaccurate with respect to some property or other.

That said, I decided to see if I could give a basic feel for steel properties without compromising accuracy too badly. I started with just the stainless steels. Please let me know what you think. Note that I had to use rather coarse groupings.

Here it is, let me know if you think the oversimplification is so bad as to make this counterproductive:

Because stainless steels are often heat treated to around the same hardness
(i.e., 440C is usually around 57 Rc, ATS-34 is 59-61 Rc, S60V is getting
consensus at around 56 Rc, etc.)
it's a bit easier to give a general feeling of the performance you'll get from
different classes of stainless steels, without introducing too many
inaccuracies. Here is a general categorization of stainless steels:

420J and 6A represent the low end of stainless steels. They are very stain
resistant, and are tough due to being very soft. However, they are also very
weak, and not very wear resistant. Generally speaking, expect these steels
to lose their edge quickly. 6A is finer-grained and takes a sharper edge,
due to the vanadium content.

440A, 425M, 420HC, 12C27, 8A, Gin-1, ATS-55 represent the next level
up. They can get harder and stronger than the previous group, and are
generally more wear resistant. All are very stain resistant (less so than
the previous group), though ATS-55 lags badly in this area.
All are getting to the point where wear resistance is getting okay.
A few points worth noting: 12C27, due to its purity, can perform really
well when heat-treated right. 8A is the finest-grained of the group and
can take a very sharp edge. Gin-1 is probably the wear-resistance
champ of the group.

440C, ATS-34/154CM, VG-10, and S60V are the next group up. 440C is more
wear resistant than all the previous steels mentioned, but not quite in
the same class as the rest in this group. However, it is tougher and more
stain resistant, though it's also weaker. It's difficult to make generalizations
about ATS-34 and 154-CM -- they are in such widespread use that heat
treat varies widely. These steels provide a high-end performance benchmark
for stainless steels, and hold an edge well, and are tough enough for
many uses. They aren't very stain resistant, however. VG-10 can be
thought of as being like ATS-34 and 154-CM, but doing just about
everything a hair better. It's a little more stain resistant, tougher,
holds an edge a little better. And VG-10 has vanadium in it, it's fine-grained
and takes the best edge of this group. S60V has by far the best
wear resistance of the group, though consensus is becoming that it
should be left around the same hardness as 440C (56ish Rc), which
means it will be relatively weak compared to ATS-34, 154-CM, and
VG-10. S60V is the winner here when abrasion resistance is much
more important than edge strength.

BG-42, S90V, and S30V constitute the next group. BG-42 has better
wear resistance than all the previous steels except for S60V. It is
tougher than ATS-34, and more stain resistant. It is wear resistant
to the point where it can be difficult to sharpen. S90V represents
the ultimate in wear resistance in the steels discussed so far.
Also tougher than ATS-34, and more stain resistant. It can be
very difficult to put an edge on. It is difficult enough to machine
than it is used almost exclusively in custom knives, not
production knives. In your buying decisions, you might want to
take into account the difficulty of sharpening these steels.
S30V backs off on the wear resistance of S90V,
but is significantly tougher and easier to sharpen. It is more wear
resistant than BG-42. The jury is still out, but it may end up this
week's ultimate high-end all-around stainless steel, due to
high performance coupled with easier machineability and
sharpenability than the other steels in this class.
 
Thanks, Practical Use!

BSC, I have no direct experience with S30V, so I can only go by what I've read, from people I trust. Reeve is the one guy I know coming in around 56-57 RC (I think), and the main reason seems to be to keep it easy to sharpen. Others seem to be coming in at 59-60, and no harder. Based on a post of Jerry Hossom's, I'm interpreting this to mean that no one has come up with a heat treat the gets S30V to perform where we'd hoped it would at 62 Rc.

Since edge strength is an important factor in edge holding for many types of cutting, my guess would be that I would tend to favor the harder 59.5 Rc heat treat over the softer 56-57 Rc heat treat, even though the harder version will be more difficult to sharpen. This is nothing but a guess though, not having actually gotten my dirty mitts on any S30V yet.



Joe
 
Not bad however I can see a difference in how steels are viewed by people. For exsample I would rank VG-10 higher than BG-42 in every class. In my use of the 2 VG is alot better than BG.
 
Joe,
Pretty similar steel division I have done in my book (should be available in Poland around Christmas). I have divided all blade steels into 3 groups:
  • Minimal steels like 420J, 440A, AUS-6, 420HC etc. – very rust resistant due to low carbon contents, weak, easily bending but practically never cheeping edge, easy to sharpen and equally easy to dull.
  • Reasonable steels like 440C, AUS-8, VG-10, ATS-55 etc. – less rust resistant, better edge hold, still reasonably easy to sharpen, good balance between toughness and chipping resistance. Good steels for heavy duty, outdoors knives.
  • Extreme steels like ATS-34, 154CM, BG-42, CPM 440V etc. – even less rust resistant (excluding CPM 440V), excellent edge hold, pretty hard to sharpen, edge is quite brittle and chips on abuse practically without pre-bending. Good steels for knives intended for pure cutting like hi end folders, small to medium (3-5”) hunters and so on.
I have divided some steels into another groups than you, however these borders are not clear and transitions from one group to another are pretty subtle and barely noticeable.

My conclusion would be that within the same group the difference in real-life performance displayed by different steels is not essential. I would rely more on steel proper heat treating (provisionally evaluated basing on particular maker or manufacturer opinion among advanced users, then on my own experience) and general knife design (visible with plain eye and evaluated by myself) and less on steel composition.

All in common sense limits of course :)
 
Groupings make sense to me. I did this once for someone via EMail, came to similar groupings (may have had 5 groups though).

Probably ought to throw D2 in with the ATS-34 group since it is so commonly used and well understood.

AUS-10 probably belongs with AUS-8.

Don't have enough experience with VG-10 to comment from experience/use, but it is in/around the ATS-34 grouping.

With VG-10, it is unclear what benefit the Cobalt brings to bear, and the drop in vanadium and moly tells me, given good heat treats, VG-10 is unlikely to exceed BG-42 overall. VG-10 could well be easier to sharpen and get a good keen edge onto, relatively speaking.

Given a chance to nitpick, I'd probably stack them like this, quite subjectively since attributes can be edge holding to toughness to corrosion resistance.
From low end to high end:

420, 420J, 6A
440A, 425M, 12C27, 420HC
8A, Gin-1, ATS-55, AUS-10
440C, S60V, (different steels, w/ different pros/cons that balance)
ATS-34/154CM, D2, VG-10
BG-42
S90V (great edge holding, but toughness keeps it from the top)
S30V (great overall balance, so it exceeds them all)

S60V has great wear resistance, but I'd take a well heat treated blade of ATS-34 or VG-10 anyday, as I'd rather the Rc60 than Rc56 for most uses. (i.e., abrasion resistance is good, but I generally want resistance to rolling/impaction 1st, abrasion resistance 2nd).

Which says in summary, your rankings look fine to me.

YRMV.
 
I dunno. I thought your original article was fine.
You partially sorted them to the "worst to best" order. But I thought the individual explanation was better because it shows where this particular steel shines, and where this particular steel belongs to the crapper. For example, in 420, you've stated that it's used dive knife because it's not going to rust as you dive.
Nevertheless your classification is very nice and certainly would help the newcomers.
 
Calyth,
My grouping is very, very shortened and simplified here. In the original form it is quite decent part of full sized book (not short brochure), however I’m too lazy to translate it to English in whole. It also contains pretty extensive explanation why I have grouped steels this and not another way. For example I threw BG-42 into the same group with ATS-43 because I didn’t notice significant difference in their performance looking from overage, practical user’s viewpoint.
I also threw VG-10 into the same group with AUS-8 not because it is any “worse” than ATS-34 but because it is significantly tougher and less prone to chipping.
My grouping to minimal – reasonable – extreme inherently is somewhat different than simply bad – better – good. I have tried to divide steels more according their performance than evaluating how “good” they are.

This is based on my experience. However we have experience not with steels as itself but with particular blades. A lot of factors influence their performance like heat treating, edge geometry, etc, etc, even handle shape. So our experience and impressions on particular steels not only could be different, in my opinion they simply should be different.
 
Thanks, guys. This thread is the best I have read about the differences between stainless steels. Despite having read many posts about steels over the past year, I feel that I know alot more now after reading this thread.

For example, among the low end steels, I did not realize Aus6A was not as good as 440A and 420HC, and should be grouped with 420J.

This may not be possible, but what would be really helpful is if someone could rank the large manufacturers as to the quality of their heat treatment.
 
This is an excellent thread indeed! I am wondering why there is no mention of the 14-4 CrMo steel that Microtech is now using. Is it so similar to ATS-34/154CM that it is not worth mentioning or??
 
Hmm, I couldn’t put AUS-6 steel any lower than 440A. I have some CRKT’s, some SPYDERCO’s in AUS-6, some SOG’s and some JOKER’s (Spain) in 440A and I didn’t notice any significant difference in their performance. They are also closely comparable with 420HC...
Probably I should put 420J a step lower, as very, very minimal steel what could be used for knife blades at all.

However as said – we all deal with particular blades, not with steels as itself.

For example, I have heard a lot of complaints about ATS-55 stain resistance out here. On the other hand my personal experience with SPYDERCO Delica in ATS-55 doesn’t match such complaints. I have carried my Delica inside the waistband of beach shorts, close to my body, spending last year vacations in Croatia. It was pretty hot there, very salt sea was as close as possible (our apartment was closer than 100 m from seaside). But it displayed no rust at all, even marginally!

Year before it was put into similar conditions near Baltic sea. Baltic is way less salt but inside the waistband the knife is pretty subject to sweat influence...
Additionally I didn’t use something like Tuff Cloth (spelling?) on the blade since it is not available here. My blade was just once wiped with Break Free CPL before vacations.

Was this enough to protect continuously used (fruits, breakfast rolls, some barbecues etc.) knife for two weeks or ATS-55 is less prone to stain than it is claimed here?
I don’t know, I just share my experience...
 
Very well done Joe. What you have endeavored to do here is very difficult. Without going into much more detail on each steel, your listing does a good job of giving a general ranking of the steels listed. I really appreciate all the work you have put into your Steel FAQ. Now, how about those low chromium high carbon steels?
 
I am glad to read that some would not group Aus6 with 420J. Now I will rush outside and retrieve my CRKT, SOG, etc. Aus6 knives from the garbage can before the truck comes buy.

Seriously, I was disturbed to see Aus6 grouped with 420J. I would never buy a knife made from 420J, but have bought Aus6 knives from the aforementioned reputable manufacturers. My impression has always been that 420J is at the bottom of the barrel in knife steels, and should only be used to make knives that are free prizes in Cracker Jack boxes.
 
Heh, maybe I'm being a little tough on poor 6A. This was a quickly-scribbled first-pass for your comments. The original FAQ had 6A positioned next to 440A. I might introduce another layer than looks exactly like rdangerers 2nd line, with 440A and its cousins sitting there, and Gin-1 and its cousins above that. rdangerer agreed with my post that 6A belongs with 440A, and frankly I think it kind of fits between the layers: 6A is either the best-performing of the lowest-tier steels, or a weaker cousin on the 440A line.

Keith, I'm not sure if you saw my comments in the other string, but I admit I'm thrashing a bit when it comes to ranking the non-stainless steels in this manner. Non-stainless steels are a lot more versatile than stainless steels, and anytime I try to simplify things, I find that I'm introducing too many inaccuracies. I'd appreciate getting ideas on how to approach this one.

Let me outline some of the problems I see. First, with stainless steels, any particular stainless is usually heat-treated to around the same hardness, regardless of the knife maker. They tend to have a narrow range within which they work well, and beyond that range, you might as well pick a different steel. With non-stainless steels, there are often huge ranges within which the steel can work: 5160 from low to high 50s, 1095 from low 50s to low 60s, M2 from high 50s to mid 60s, etc. If I say 5160 is tougher than 1095, I worry about a reader seeing a 5160 knife tempered very hard, and a 1095 tempered much softer, and assuming the comparison still holds. Okay, I could narrow things down by saying that 5160 is tougher than 1095 if they are both at the same hardness, but this doesn't apply to many of these steels -- when do you ever see a 5160 and D-2 knife both left at the same hardness? For these steels, I have to make a more absolute comparison. And now take into account differential tempering, which is popular with several of these steels -- is the high-50s 5160 still more durable than a differentially-tempered 1095 knife?

Remember my point here is to simplify the understanding of these steels, while trying to avoid introducing even worse sources of inaccuracies. One thing I could do is reproduce the above warning in the FAQ, about the wide ranges within which these steels work well, and about differential tempering, and the subsequent difficulty in doing a simplified comparison. Then, perhaps limiting the comparisons -- comparing the 10xx series to 5160, comparing the CPM steels to each other, comparing M-2, D-2, A-2 to each other, etc.

Joe
 
Thanks for the great work Joe!
I would suggest that you list the steels in increasing order of carbon content. I tend to think of stainless steels with more than about 1% carbon as being premium steels, since the manufacturers charge more for them since they a difficult to make by fine blanking, infact, many are laser cut. These higher carbon steels also tend to hold their edges longer than the lower carbon "nonpremium" steels.
Also, I would suggest that you would invite knife makers to comment on the steels that they use, and add these to your comments.
It would be nice to add info on edge holding, toughness (impact strength), rust res., etc., but unfortunatly, little detailed information of this type is avalible, and is complicated by differing heat treatments.
Another idea: add an advanced steel study area for those who are into more details, that way you can leave the introduction simple for noobs. Thanks again.
 
Given the importance of heat treatment, would it be possible to rate manufacturers on quality of heat treatment? It seems that such information would be just as useful as knowing the difference between types of steel.
 
Frank, a lot of interesting ideas. I definitely would like knifemakers to comment on the steels they are using ...

One note about your idea to list steels based on carbon content. If you look at the groupings above, they kind of are in carbon-based groupings (my revised version even more so). I say kind-of, because despite 440V's carbon content, 440V's lack of toughness, and resulting soft heat treat that leaves it weak, makes it in my mind more of a competitor to ATS-34 than to BG-42, although even that isn't strictly true (440V is turning out to be a pest, ruining my nice clean groupings :) ). rdangerer put 440V in with 440C, presumeably because he decided that strength (or lack thereof) was the uniting factor, and I can't say his way doesn't make sense. Serg's groupings make sense too, although I find his grouping of VG-10 odd :) I really like that stuff.

Joe
 
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