Another Steel Question

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Could someone rate the following steels in terms of toughness & edge retention: A2, D2, M2, & BG42. Would one be best on a fixed blade and another on a folder?

Are all of those steels better than 440V but not as good as 420V?

AFAIK, nothing holds an edge as well as INFI, can anything outcut M-INFI? Talonite?

last question: What can be expected from damascus made from 1085 & nickel in terms of edge retention & corrosion resistance?

Thanks

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Jason aka medusaoblongata
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"To give is a need, to receive is mercy." - Thus Spoke Zarathustra
 
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As far as D2 and A2 are concerned these steels are both tough and have great edge holding properties when heat treated properly, as for any nickel damascus dont expect to much at all in terms of cutting performance.

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Steve Filicietti
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http://www.unitedbladeworx.com.au
 

SALTY

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Remember that carbon steels generally do outperform the stainless steels in the catagories you mention. I do, however, like BG42.
 
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Bob Egnaths steel commentary on that site:

Steels

medusa, No Way am I going to step into the little mine field your innocent sounding question creates. Too many variables, too many steels. Especially when you try to put all of those steels (carbon and stainless alike) In Between 420V and 440V. It is not an answerable question.

As for the damascus question, there should be at least one other steel in the mix. Normally, steels with high nickel (e.g. L6) or a modest chromium content are used in the mix to resist the acid etch and make bright lines. A blade made from equal parts 1085 and nickel would be terrible.

If the nickel content was low enough and was just added for contrast, it might work for a blade. But pure nickel is not hardenable and if the edge has a significant amount a nickel in it, it will not hold worth a darn. 1085, L6, and some fluxed in nickel might make an attractive blade. But I would be very wary of using a blade made from Only 1085 and nickel.

You should ask that question in shop talk and see what happens. Or email someone like Ed Caffrey at ed@caffreyknives.com who could give you an expert opinion.

Paracelsus
 

SNiPER

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CPM420-V (now know as S90V) & CPM440-V (now know as S60V). Are the 2 best steels you can get right now. Bg-42 is also really good. The other steels, like A2, D2, and other tool steels are good also, but the down side to them is that the are not stain less. That means they have a chance of rusting without even getting wet. The CPM's on the other hand are very stain less compared to the tool steels. The CPM's are very strong and will hold the best edge out of any of the steels made right now. The prosses of how the CPM steel is made is also the best, thats why the steel is pretty much the best right now. BG is really good too. The BG stands for Bearing Grade (might of spelled that wrong). Its like a tool steel but is stain less. The only reason its not as good as the CPM's is because of the process used to make it. Its a 9 out of 10 rating.

Hope this help you some.

Delta Z.
Matt

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<font face="Verdana, Arial" size="2">Originally posted by Paracelsus:
medusa, No Way am I going to step into the little mine field your innocent sounding question creates.</font>

I wasn't looking for a mine field, I was just hoping to learn a bit from those who are more educated than I. I have a 710 in M-2, a 440V Native, and a D2 Sifu on the way; I just wanted to know how the steels compare. Thanks for the info and links so far, keep 'em comin'.


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Jason aka medusaoblongata
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"To give is a need, to receive is mercy." - Thus Spoke Zarathustra
 
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As a mechanical engineer, I can tell you the same thing that many many others will tell you. It really depends on the heat treat. I mean it really depends on the heat treat.

For example, you CAN heat treat BG - 42 up to about 64 or 65 RC. Excellent hardness, excellent edge retention, almost no toughness, and significantly reduced strength. Even discussions of what optimum heat treats are differ greatly.

However, with that being said, IN GENERAL, tool steels which are not stainless typically can be heat treated to better cutlery performance levels than stainless steels. Generally, steels without chromium and vanadium can have stable grain formation and such with higher carbon percentages then can those with.

In an oversimplified sense, the way stainless steels work is that chromium (most often) fits into gaps in the molecular structure of the steel, preventing oxygen from doing so. However, the chromium doesn't otherwise really contribute to strength of the matrix, so in general steels alloyed thus will not have the performance of a non - stainless tool steel.

I'm not even going to try to differentiate between the tool steels.
 
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Medusa, sorry for the colorful language. I realize that you probably did not realize the traps and pitfalls your question created. So let me show you the way down the rabbit hole, Alice. Warning, it's going to get really weird from this point on
wink.gif


There simply is No best steel for knives. And because, as others have pointed out in this thread, the heat-treatment is the Most important part of determining the final physical make up of the steel, it would be theoretically possible to treat all of the steels you mentioned in such a way that 420V might look like the Worst steel.

Assuming optimal (what is that?) heat-treatments, all of the steels you mention will make a great knife.

I love simple carbon steels. They rust, but they take great edges, hold them for a reasonable length of time, and are easy to sharpen. I agree with the comments above about the effect of the extremely high chromium content in most 'stainless' steels changing the grain structure of the steel in a way that reduces toughness, and edge holding.

However, chromium is a strong carbide former. Small amounts of chromium in steels like 52100 (about 0.5% compared to 16% in 440C) actually help make more of the hard martensitic structure that is responsible for cutting.

Until recently, I had a real bias against most stainless steels unless rust prevention was a necessary for a knife's purpose (and it is seldom 'necessary). However, the development of crucible particle metallurgy has changed all that. CPM steels have what would traditionally be considered a ridiculously high carbon content (over 2%). The special techniques used in their making allow very high carbon content with lots of martinsitic structure, and also allow very high chromium content without adversely effecting grain size. Most of the chromium is 'free', not bound up in crystals (grains). A free chromium concentration of greater than about 12% is required to make a steel 'stain-resistant'. Most of the 'excess' carbon gets trapped in hard, small martinsitic crystals.

I really like 420V. But I won't stop buying, using, and enjoying knives made with different 'lesser' steels. If one Only considers performance of a steel as a blade, and ignores stain resistance, then some of the best steels would be: 420V, 5160, and 52100.

All of the steels you mention are great cutlery steels (except for nickel damscus). For large fixed blades you need toughness. For smaller fixed blades and folders, you can get away with a harder (less tough) blade steel, and emphasize edge holding. Many people prefer folders with stain-resistant steels for convenience, not for edge performance.

So there is Always a compromise being made in selection of steels for any particular knife application. Toughness, edge holding, and stain-resistance are all sort of conflicting properties of a blade. Any steel can be heat-treated in a way that will emphasize toughness and flexibility at the expense (normally) of edge holding. You could harden a blade so that it would hold an edge a very long time, but the blade may be too brittle to be useable in the real world.

You can not simply say, this steel is better than that steel. You must understand the different potentials that steels have for use as a knife. Heat-treatment is much more important that the type of steel. The steel (alloy) only allows a certain range of performance. It does not guarantee it. The working properties of any steel are determined by the heat-treatment. Heat-treatment effects the way the different elements in the alloy combine. That in turn determines the physical properties of the blade.

I hope this rambling post helps make it clear why your question is 'difficult' to address.

Paracelsus

 
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<font face="Verdana, Arial" size="2">Originally posted by medusaoblongata:
I wasn't looking for a mine field, I was just hoping to learn a bit from those who are more educated than I. I have a 710 in M-2, a 440V Native, and a D2 Sifu on the way; I just wanted to know how the steels compare. Thanks for the info and links so far, keep 'em comin'. </font>

M.O. --

First, the easy question. In my experience -- admittedly limited -- damascus that's made with steel plus nickel is almost always damascus that's made for aesthetics, not performance. I suggest talking to the maker directly about that; I've found makers are often very up-front about the capabilities of their damascus. If he tells you it's a performance steel, talk to some other damascus makers and see if they agree that a nickel-based damascus can provide high-performance (they've always told me: no).

Generally speaking, I've found M-2 and D-2 can perform similarly. I think the general rap is that D-2 will hold an edge a bit better, and M-2 might be a little tougher, when given a "typical" heat treat. However, this really is heat-treat dependent, and there are other dependencies as well. I have no idea how REKAT's D-2 performs, but I won't be shocked if you don't see much difference between the M-2 and D-2 blades. On the other hand, if REKAT chose to highlight D-2's wear resistance properties, you may find REKAT's D-2 blade more wear resistant and less tough than Benchmade's M-2. That's the beauty of al this ... we won't know until we test it out!

Benchmade's M-2 blades are much tougher than their ATS-34 blades, seem to hold an edge better, and take a sharper edge, too.

I have no experience with Spyderco's new, softer 440V. Reports are all over the board on it. Some folks report that the new softer heat treat gives 440V acceptable toughness, but retains the excellent wear-resistant properties 440V is known for. But there are other folks who say the wear resistance has decreased to ATS-34 levels, and the softness has reduced strength to the point where the steel dings easily. I don't know where the truth lies. Someday I'll pick up a 440V Spyderco with the new heat treat and take it for a test drive.

I know that when you start out trying to learn all this, you become desperate for a neat list that orders the steels according to certain properties. Unfortunately, any such list is bound to be incorrect in some parts, because the theoretical performance is made very blurry by practical considerations, such as the heat treat, the quality of manufacture, etc.

Even steel experts can end up disagreeing on steel properties. Bob Engnath said that D-2 takes a terrible edge and holds it forever. Meanwhile, D-2's most expert use, Bob Dozier, gets his D-2 to take an edge that has to be felt to be believed. So here we have two experts whose experiences are practically opposite, probably based almost solely on the fact that Dozier has figured out how to make D-2 perform the way he wants.

Joe

 

Cliff Stamp

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medusaoblongata:

<font face="Verdana, Arial" size="2">Could someone rate the following steels in terms of toughness & edge retention: A2, D2, M2, & BG42. Would one be best on a fixed blade and another on a folder?</font>

M2 is a very wear resistant steel with a good amount of toughness. A2 is tougher but not as wear resistant. D2 is more wear resistant than A2 but not as tough. To get more specific, M2 at 66 RC has a 25% increase in toughness over D2 at 58/60 RC. It will also be stronger and significantly more wear resistant. A2 at 60 RC will have 70% more toughness than M2 at 66 RC and over double the toughness of D2 at 58/60 RC. However the wear resistance is significantly lower than either of the two.

You can of course by varying the heat treats drastically change the relative strength, toughness and wear resistance. For example if you raise the tempering temperature for M2 you can drop the RC down to about 60 and thus its advantage in strength and wear resistance over D2 at 58/60 RC are reduced, however it now has far more than a 25% increase in toughness. You can do similar things with the other steels. However you are generally better off with varying a steel than doing that as the grades were designed for specific things.

In short, since A2 is tougher I would rather it for a larger blade, if I was forced to pick among the ones listed, if I had a choice I would go with something still tougher. Since M2 has more wear resistance and strength I would prefer it for a small folder.

<font face="Verdana, Arial" size="2">Are all of those steels better than 440V but not as good as 420V?</font>

The high alloy CPM steels are very brittle, you can make them decently tough by dropping the RC, but then you end up with blades that are of low strength and compression resistance so they roll and indent readily. I prefer CPM-420V heat treated as by Phil Wilson. It is left very hard (59 RC) and thus will chip readily, but if used for a light use blade will hold a edge for a long time becuase of the high strength and wear resistance. However I would assume that M2 at 66 RC would resist rolling more, but wear faster.

<font face="Verdana, Arial" size="2">AFAIK, nothing holds an edge as well as INFI</font>

Lots of steel does, CPM-10V will easily. The problem is that INFI has a broad range of abilities that is difficult to outperform in total. It is far tougher than 10V as well as significantly more corrosion resistant.

And just to stress, as the other have, the heat treat is very important, and as a general rule, the more complicated the steel the easier it is to screw up. Even the best steel will be no better than 440A and possibly worse if even a small mistake is made in the heat treat. As well, you can vary the properties of steels all over the blade by varying the heat treat, be sure to discuss how the heat treat is being done to make sure you are getting what you need, simply getting the right steel is only half the solution.

-Cliff
 

dogboye

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<font face="Verdana, Arial" size="2">Originally posted by Joe Talmadge:
....Someday I'll pick up a 440V Spyderco with the new heat treat and take it for a test drive. .....</font>

That is a review that I would REALLY like to see.

As for me, I'd take any/all of the steels in the original post over 440V (S60V), in any knife, and make do. The only way I'll buy anything else in S60V is if it is a design that I REALLY like, and it is not available in any other steel. The LtWt Native is a good example.

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iktomi
 
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Thanks all for the information. I'm starting to understand and I appreciate your patience with my ignorance.

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Jason aka medusaoblongata
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"To give is a need, to receive is mercy." - Thus Spoke Zarathustra
"Cutting his throat is only a momentary pleasure and is bound to get you talked about." - Lazarus Long
"Knowledge is not made for understanding; it is made for cutting." - Michel Foucault
 
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