Maxamet - the ultimate Mule steel

[Cliff Stamp]

Would this be fairly fine grained or not?

The austenite grain size is generally very fine on all HSS due to the high amount of alloy which prevents grain growth, so yes. The carbide size is also small due to the mainly MC type carbides and the PM forming - however there is so much carbide that it is going to segregated into 5-10 micron clusters. There is also going to be a LOT of carbide. These steels can be a little tricky to sharpen because the edge can be very fragile, especially if you try to take it to a high polish.

Would this be somewhat stainless even with only 4.75% chromium? What do cobalt and the other alloys do for stainlessness?

That chromium will go into solution (not be left as carbide) due to the very high soak temperatures used and thus you will find that :

-this does not take a natural patina well

but it will not have enough chromium to resist strongly corroding environments and will have a mix of surface and pitting if left exposed to salt water and similar.

It would be similar to M4 for example.

In general :

-vanadium adds to wear resistance by forming MC primary carbides
-tungsten raises the secondary hardening and hot hardness by forming secondary MC carbides
-cobalt keeps ferrite (soft/weak) out of the final state (ideally is pure martensite)

Would this behave more like the tool steels i'm familiar with only much harder?

Essentially yes, that is what it is made to do, replace those steels where they wear too fast or deform too easily. In knives though care has to be taken because at some point there is so much carbide in the edge that it will have issues being retained in the very thin cross sections of the edge and then it tears out rather than be worn. However this can be compensated by running higher edge angles and/or more coarse finishes as well.

... how you are planning to have these knives assembled

In general I tend not to prefer full tang knives, it is a waste of steel to put it there as it does nothing functional (most people end up drilling it all out anyway).

I believe Kyley Harris (cKc knives) was the first maker to really speak out about very short tangs. His argument is that very short tangs on fixed blades are still much stronger than the same size tangs on folders.

If you have that as perspective it should be obvious that in general, unless you are snapping off folder handles on a regular basis then a solid pinned short tang will be easily strong enough.

I have not asked Jeremy exactly how he is doing it, he is talented enough to figure that out, I assume it will just be a pinned construction with a spacered handle.

ROFL. Nice troll thread Cliff. :D

Dude, just because you are not an operator ...

[Laethageal]

Hey Cliff, nice thread as usual. I was wondering if you would have one of your blade sold... (to me) to help cover your cost of making ? I'd really be interrested in trying to make a folder out of that thing. Leave the three holes out of one and I'll take it!

[Nate]

I have ground 121REX (a similar CPM steel)

Given the similarities, do you have any expectations on how Maxamet will differ from 121 Rex?

http://zknives.com/knives/steels/steelg ... hrn=1&gm=0

[bearfacedkiller]

Thanks cliff. I have learned a lot from your posts and appreciate you answering my questions. I like to run acute angles so far from my experience, loving my SB delica run at about 24/30. I understand the carbide tear out with high alloy steels. That was discussed in a recent s110v thread as well. I don't think the new high allow steels that are all the rage have got me totally hooked yet. After years of enjoying basic carbon steels I am still getting used to the high alloy steels. Initial opinion of them was poor but I am figuring it all out. I keep my s30v para2 at 30/40 with a medium or fine finish and keep my SB delica at about 24/30 with an ultra fine finish. That is a very common edc combo for me.

I have a forum native5 and a s110v mule and with limited experience find the edge to sound toothy when cutting paper even when the edge is very fine. Does the carbide tear out create a very sharp toothy edge when the carbide quantity is this high. I haven't experienced this with s30v or any of my other steels. When I polish s30v sometimes it doesn't cut as well beacuse the edge slides so smoothly. My forum native, even when taken very fine, doesn't just slide rather than cut. I assume this is the carbides either cutting or tearing out and leaving a toothy edge.

Is there an advantage to carbide tear out when the contents get crazy high due to its ability to keep the knife cutting?

[Niles]

High edge angles and a coarser grind sound perfect for my general application...I'm in for a mule or two! How about a bushcraft model?

[Cliff Stamp]

Does the carbide tear out create a very sharp toothy edge when the carbide quantity is this high. I haven't experienced this with s30v or any of my other steels. When I polish s30v sometimes it doesn't cut as well beacuse the edge slides so smoothly. My forum native, even when taken very fine, doesn't just slide rather than cut. I assume this is the carbides either cutting or tearing out and leaving a toothy edge.

There is a lot going on in this question, I will try to generalize a few points.

In general people often claim that certain steels cut better, or are more aggressive or have more bite - this is all fantasy/false. The main reason for it is that very high carbide steels have a very low grindability and thus it is easy to leave coarse scratches in the edge and thus while the bevel may look polished the actual apex is quite coarse.

Now there is an exception to this in that if you take a very high carbide steel to a very low angle and try to put a very high polish on it then the apex will fracture due to the low edge stability of the steel. However this isn't a benefit because while the apex is rough the sharpness is very low compared to an edge which is coarse because the steel is actually cut.

To understand this, imagine breaking a piece of wood, now you might get a sharp point to use as a stake and you might not. Compare that with cutting a point on the wood to make a sharp point. The same happens with the edge of a knife, in general it will get sharper if you cut it with an abrasive than if it breaks apart because the angle is too low for the steel.

This is further complicated because in general (just general) higher carbide steels often have better hardening. This means they can often be easier to take a crisp edge where lower carbide steels because they are used on less expensive knives often just get very basic hardening and thus the edge can roll/deform easy in sharpening and end up with an edge which in some ways is sharp but in other ways is not.

To really see the difference between them you have to have knives which have similar levels of heat treatment optimization or else all you see in some cases is which one had the better hardening.

Is there an advantage to carbide tear out when the contents get crazy high due to its ability to keep the knife cutting?

This is an often promote "feature", however while it does work, the sharpness obtained is very low, as in on the order of 1% of optimal. Given how easy it is to sharpen any knife on almost any material and get a result better than 1% of optimal I don't see this as anything more than an academic curiosity.

I discussed it in the late nineties and took it to the limit with very coarse steels with very coarse finishes at very coarse edges (D2, 100 grit finish, 5 dps). It is an interesting experiment to do, but practically it is hard to see the benefit to that kind of fracture based edge holding because again the sharpness is just so low.

The other thing is that outside of cutting stock materials in experiments, I have always found that in general I sharpen when the blade gets damaged from accidental contact. If this can be avoided and you only cut clean materials then edge holding is so high on any modern steels it is rarely a considering factor.

I recently gave a Havalon Piranta to some friends who all hunt big game. This uses replaceable scalpel blades, a very basic stainless steel. They never replaced a blade on an animal (moose mainly) unless they broke it off (I asked them to attempt to do that specifically to see how hard it was to do) and could easily handle an entire moose with the same blade.

Given the similarities, do you have any expectations on how Maxamet will differ from 121 Rex?

That was one of the reasons I was interested in Maxamet.

121REX takes Maxamet's high hot hardness and high direct hardness and pushes the wear resistance to extreme levels by increasing the vanadium content.

121REX will have thus lower edge stability but higher wear resistance. The curious part then is exactly at what angle/finish will each end up being optimal. 121REX has to be higher and Maxamet lower, but how much?

I have tried 121REX at 15 dps/600 DMT and the edge holding on abrasive materials (cardboard) isn't impressive, I believe the edge is micro-fracturing which would make sense and explain the results but I can't see it with 50 or even 150X linear magnification. I am going to run it at a higher finish and higher angle which has to stop that and see what happens.

In any case it will be interesting to explore.

I was wondering if you would have one of your blade sold... (to me) to help cover your cost of making ?

These are going to be part of the T0.1M mule project, which means if you want to actually try them out then all you need to do is :

-ask
-be willing to publish all data on use
-engage in the peer review process (discuss your results)

It is part of a project to build a library of blades, which will contain all reference material on the steel, work done by various individuals and direct materials testing. It is intended to provide knowledge on steels and cut through the shill/propaganda/misinformation which is common in the industry. It is also an open design project which means the design is free to use with no restrictions.

[bearfacedkiller]

Thanks again cliff. I have learned like you said that the difference in performance with cutting of different steels has more to do with my ability to sharpen them. I haven't had a lot of love for s30v because I can't get it where I want it easily. I have learned that the best steel for me is a steel that I can put the edge on I want.

It is kind of like when people worry about the performance of a car or the accuracy of a firearm when their own skill level cannot utilize that level of performance or that level is not needed. I don't have the sharpening skill necessary to utilize the farraris of steels. The performance differences I see in my steels has more to do with my own abilities and my preference for very sharp crisp edges over never ending working sharpness.

There is no limit to how deep this rabbit hole goes I guess. I'm more interested from a geeky science perspective so thanks for entertaining questionsthat are more academic than pragmatic.

[Cliff Stamp]

I haven't had a lot of love for s30v because I can't get it where I want it easily. I have learned that the best steel for me is a steel that I can put the edge on I want.

S30V has two common problems, one which can't be avoid and one which can and if you get two of them it can be the perfect storm of edge sharpening frustration.

It is a high vanadium steel and vanadium carbide is actually harder than most sharpening abrasives. In general, unless you use decent stones and/or are experienced with high vanadium steels this can cause problems itself.

It takes longer to grind, this often makes you want to use more force which over stresses the edge, makes heavy burrs or makes the edge just crack apart as you try to refine it. It also can make you skip steps and move ahead too fast in grits and end up with a too fine grit which can't do anything as there is too much material to be removed.

The first thing you should do is that when you sit down give yourself at least twice as much time on S30V as you do on VG-10 and at least 4-5 times compared to steels like O1. If you know that going in it gets rid of a lot of the issues. Now you can also compensate by using higher end stones, the Sigma Power Series for example easily grinds steels much harder to work than S30V - but if you have basic stones, be prepared for more time.

The second is don't skip grits until the work is done, how you know this can be determined in any number of ways. The method I use is very simple and I have described it in detail elsewhere. But it is critical you don't skip grits on hard to grind steels.

The killer though is when you get the other problem, the steel doesn't have a really nice hardening. If the steel has non-martensite phases, then the edge can be very hard to set properly as it will be gummy, not want to form crisp and just be troublesome. There are ways to deal with this (minimize burr formation methods) as well.

In general the first thing I would recommend is applying a relief grind, what ever angle you are going to sharpen, cut a few degrees off of it and grind the edge to that angle. Stop just short of it being sharp and then sharpen as regular at your normal angle. This relief angle you only really need to do once (unless you have extreme wear) but it will almost eliminate many of the problems noted in the above.

In general though, just realize that under it all, all you are trying to do is form a point of a wedge, at a basic level it is very simple. It only gets complicated when you let it, a little physics goes a long way as always in solving the problems.

[razorsharp]

I have wanted to to try try this This steel for a long time. Cliff, do you think you could could ask the maker of your knives where he got the stock? I would love to make a couple knives from it

[Cliff Stamp]

Cliff, do you think you could could ask the maker of your knives where he got the stock?

Me, I obtained it directly from Carpenter with my winning personality.

I will check and see if they have any more bar stock.

[ChapmanPreferred]

Sounds like a good Mule steel.

[razorsharp]

Me, I obtained it directly from Carpenter with my winning personality.

I will check and see if they have any more bar stock.

Thank you sir

[bearfacedkiller]

Thanks for the tangent cliff. Sorry for pulling the thread off track everybody. Much appreciated. :D

[Cliff Stamp]

As an update :

http://www.youtube.com/watch?v=5Xi8qLaign4

I asked Jeremy to try traditional methods just to experiment with how difficult this steel is to work, the above video is an amusing example of that. Note as well that unless you pick the right belt and the correct abrasive size the belt will suffer catastrophic failure almost immediately as well. Again this really isn't a steel as much as it is a steel-like replacement for solid carbide.

[Trevitrace]

Did he also say that that was annealed? Softer, right, Cliff?

[Cliff Stamp]

Yes that is annealed, however this is an extremely high carbide steel so the amount of carbide when annealed is going to be very large (the carbide volume is higher when annealed than when quenched). In order to grind it well you have to have an abrasive which is much larger than the carbide size and thus it can cut by ploughing. If the abrasive size is similar to the carbide size then the abrasive and carbide wear against each other and since so much of the carbide here is very hard (tungsten/vanadium) it can wear the abrasive almost as fast as it is worn itself.

This is easy to understand if you think about what happens if you try to rake your fingertips through fine sand (this is an abrasive much larger than the carbides) vs if you try to do the same with coarse rocky ground (this is the abrasive the same size as the carbides). If the rock is of similar size to your fingers you can get direct contact forces between your fingers and the rocks which will really slow down your ability to move the rock. It is also easy using the same analogy as to what happens if you try to use an abrasive smaller than the carbides (what happens if your fingers are actually smaller than the rocks).

[sal]

Hi Cliff,

I guess you got the small pieces that Ron had. They have agreed that they will make us some, enough for a Mule Team. Ron said he might have a piece around for us to test.

sal

[Invective]

Hi Cliff,

I guess you got the small pieces that Ron had. They have agreed that they will make us some, enough for a Mule Team. Ron said he might have a piece around for us to test.

sal

This is great news, thanks for always catering to the steel junkies Sal!

[Cliff Stamp]

Sal,

I have a fairly large piece Ron had lying around, it was not ideal for a knife unless you wanted to make a machete from it, but experiments are not always ideal.

http://www.youtube.com/watch?v=vcYmQaf0fjk

[Holland]

Very interesting steel indeed