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The Mastiff wrote:And, CPM M4 would still outperform it in some ways. :) I like the edge that the high tungsten M2 class steels give which is why I want to try the M3 class. truly though CPM M4 is a tough act to follow. At the prices Sal quoted and less performance than M4 I say ,Why?

Joe

It's one of those steels that hasn't been used enough in knife blades to know much about it yet.

There is a tendency for CPM M4 to work harden in the very thin geometry of a knife blade. Blade sports competitors push the limits and some of these very thin blades work harden and fracture or crack after a year or two on competition, and are replaced. Personally I used 52100 clad with 15N 20 for several years, and the knife is still undamaged. For large blades I prefer high Carbon to stainless or high speed steel. I like to think that my blades will outlive me.
There are many special purpose steels that will give exceptional life with light cutting tasks. Many of these steels will be used and do well in folding knives, it depends on what you like in your knife...Tke Care...Ed

Ed, that's a very interesting mix of steels. Your cladding makes very good knives itself, and 52100 is, 52100. I can see why you would plan on it lasting. It's a very tough, sharp combination with good wear by the sounds of it. I'd love to try a knife in it someday.....hopefully. :)

I got that similar "why didn't I think of that?" feeling when I first read about 3V/CPM 154 Damascus.

Joe

Joshua J. wrote:I don't particularly see anything special in the alloy or the heat treat, what makes this stuff so expensive?

It is a fairly specialty alloy which is designed for high hot hardness (it has extreme temper resistance), adhesive wear, and high maximum hardness. The alloy content is high, the grindability and machinability is low, and it requires very high aus-soaks and high tempering, as do all HSS. Out of the properties listed, the only thing useful for knives is the high maximum hardness which can in fact be exceeded by 1095. It is a curious thing that it appears that only the knife industry uses alloys really not designed for its industry. You don't see someone wanting to make jackhammer bits out of D2 for example, but people will constantly want to make knives out of materials which were clearly never intended for knives and have properties which are of no use for knives.

Cliff, how much of a difference does it actually make to have the grain running edge to spine rather than heel to tip?

It is about a factor of 10, the difference is huge. I actually believe this is one of the reasons why on occasion you can see huge swings in durability in knives where some guy will take a 1/4" blade and try to split a piece of wood and the knife snaps like glass. If the guy who made those knives cut them so the grain was spine to edge that would explain that.

Not to question your knowledge, Cliff, but I would really like to know where this factor 10 comes from.

I know that rolled screw treads are about 15% stronger than cut treads because of the same phenomena, but didn't know that factor was so much bigger in hardened steels.

Ed Schempp wrote:There is a tendency for CPM M4 to work harden in the very thin geometry of a knife blade.

Ed, are you sure that it is work hardening? It would seem to me that it is more likely that either :

a) They are leaving retained austenite in the blade intentionally to get toughness as the first blades used with the stock heat treatment failed catastrophically at the edge. If this is the case, and the edges contain high amounts of retained austenite then what you said is likely to happen which is one of the reasons retained austenite is horrible for a knife.

b) Many of the video's/comments I have seen show very light sharpenings on the blades, stropping and similar. This is a very bad idea for any knife which does impact work. There is little to no wear in the competition cutting but significant deformation and so of course a light stropping will restore the edge but if you do not get rid of the damaged metal then the cracks will continue to grow and sooner or later the edge will then blow out.

But I would agree that 52100 or a similar low alloy steel would be a more suitable choice, it is a very odd thing to make a competition cutting knife out of a high carbide HSS when the competition cutting has nothing that demands high wear resistance, high temper resistance and of course it isn't hardened to take advantage of the high max hardness either, as it is far too brittle there (which it has to be given the alloy content).

Hi Cliff,
Probably some of both, I've just noticed quite a difference in the grain structure in the resultant pieces. This is much finer but similar transition in the many work hardened failures I've caused farming...Take Care..Ed

Ed, really appreciate the details, that kind of information is very rarely discussed.

Thanks Cliff,
I'm a farmer not a metallurgist, I appreciate the technical knowledge that you and others bring to the forum, I am a student of steel whether I like it or not...Take Care...Ed

sal wrote:SSSsssssooooooooo,

You guys want a steel that costs 3 times as much as S90V, more to process and turn into a blade, and then you complain that our knives cost too much?

sal

Lololol. I'll take more S30v please, and ZDP-189. Heck, I like VG10. :D

sal wrote:SSSsssssooooooooo,

You guys want a steel that costs 3 times as much as S90V, more to process and turn into a blade, and then you complain that our knives cost too much?

sal

Though I have been keeping up with this thread...not sure why I didn't post this sooner...but yes, but only because this is a Mule. If it were in a full production folder, no. Then it would be far far too expensive. But I think that the striped down option of a Mule would be something that would appeal. Especially since it is something that more of the steel snobs (though I don't really like that term) buy rather than a general EDC knife user.

The Mastiff wrote:And, CPM M4 would still outperform it in some ways. :) I like the edge that the high tungsten M2 class steels give which is why I want to try the M3 class. truly though CPM M4 is a tough act to follow. At the prices Sal quoted and less performance than M4 I say ,Why?

Joe

Maybe Sal should look for Böhler K490

Same wear resistance as PM23 / M4 but double the toughness :eek:

neo wrote:Maybe Sal should look for Böhler K490

Same wear resistance as PM23 / M4 but double the toughness :eek:

That sounds very interesting.How hard can it be taken to?

Edited: Apparently 64Rc is in K490's range.

K490 does look impressive. I wonder how difficult it is to get and how expensive it is?

I still wouldn't mind trying some traditional knife steels like W2, A2, and most definitely newer stuff like CTS B75 or standard BG42 even. How about CPM 154 at around rc 61?

W2 at rc 61 or so would likely make an impression sort of along the lines of the Super Blue. It makes great knives. :)

In fact the swedish steel that Ed was talking about, 15L20N , or L6 would be another knife steel classic. Lots of work yet to be done.

Joe

The Mastiff wrote:K490 does look impressive. I wonder how difficult it is to get and how expensive it is?

I still wouldn't mind trying some traditional knife steels like W2, A2, and most definitely newer stuff like CTS B75 or standard BG42 even. How about CPM 154 at around rc 61?

W2 at rc 61 or so would likely make an impression sort of along the lines of the Super Blue. It makes great knives. :)

In fact the swedish steel that Ed was talking about, 15L20N , or L6 would be another knife steel classic. Lots of work yet to be done.

Joe

Yep, that's the catch. :)

I'm still loving the edge that 52100 very easily takes on my kitchen knife.

The Mastiff wrote:K490 does look impressive. I wonder how difficult it is to get and how expensive it is?

I still wouldn't mind trying some traditional knife steels like W2, A2, and most definitely newer stuff like CTS B75 or standard BG42 even. How about CPM 154 at around rc 61?

W2 at rc 61 or so would likely make an impression sort of along the lines of the Super Blue. It makes great knives. :)

In fact the swedish steel that Ed was talking about, 15L20N , or L6 would be another knife steel classic. Lots of work yet to be done.

Joe

Really interesting comments so far.

Joe,

If CPM-154 is so similar to RWL-34 from what I have read I can say that it can be taken up to HRC of 62 without any issues. Two of our local makers Des Horn and Gareth Bull have been using RWL-34 for some time now and I believe Andre Thornburn or Andre van Heerden has been using CPM-154 in their blades.

From my experience with RWL-34 it is one of the best cutlery steels available with a fine grain structure, enough vanadium to minimise grain growth within the steel. It can take a very high polished edge and a course edge depending on your uses and keep the desired edge for some time.

CPM 154 at 62 HRC really performs extremely well, some Custom makers have been using it for awhile know.