Edges and Steels

HoB said:
Weren't you the person who claimed superior knowledge over Cliff, because you actually had one-on-one discussions with steel makers and heattreaters?
Claimed no such thing. You can learn things in person that you cannot from internet searching and published documents. Called experience and it adds to your knowledge and has nothing to do with superiority.
If you are of the opinion that all relevant information is already available to the general public, as you indicate in your last post, then your previous claim, or rather challenge, that Cliff doesn't know what he is talking about because his knowledge is only from the scientific literature and not from discussion with actual makers, is pretty baseless.

No such opinion. All the relevant information is not available to the general public, and I'm not saying at all Cliff doesn't know what he's talking about, I'm just wondering what aspects of the PM process or industry he is investigating. I'm guessing he's searching for additional knowledge. Good for him.
I don't know what you are trying to do here, but it seems to me as well that you are trying to set Cliff up for something so I am not really surprised that you don't get a response from him.
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I'm trying to get a simple answer to a simple question. Thank you for dragging this process out.
 
Satrang said:
I'm trying to get a simple answer to a simple question. Thank you for dragging this process out.
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Again, interesting that *I* am supposed to drag this process out, when it is *YOU* who insists on getting an answer to your question, quite frankly a little bit like a little schoolboy jumping up and down. If you don't want to drag this process out, why didn't you simply drop the issue after not getting an answer in the first place? Don't try and blame this one on me. I am simply surprised why you seem to think that anyone would owe you an answer. Whether you think that the question was simple or not seems rather immaterial.
 
HoB said:
Don't try and blame this one on me.
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First off, HoB, it is your mindcontrol powers which are preventing Cliff from answering, so if you don't want to be blamed, stop squelching Stamparays with your secret signalling pyramid.

Secondly, because he so wishes, your accusor is entitled to have his question answered. It matters not if your accusor's history on this forum suggests his interest is only to sabotage Cliff's visit and that no part of his history here suggests the contrary. He asked the question and it is up to you to either furnish the information or forcefully make Cliff provide the answer. You are Cliff's keeper and your stewardship demands you answer your accusor's demands.
 
I have a question for Roman, Cliff, HoB, Larrin, KV, and anyone else who may know or have a hunch:

Of what relation is martensitic hardness to edge stability? I use some steels with high-volume, large-sized carbides (Super Gold Powder Steel and ZDP-189) and they seem to keep their shape when performing acts which have bent and broke softer steels. Would a lower-carbide steel at a similar hardness be better, worse, or the same at resisting plastic deformation and fracture?
 
Thom, nice straight forward question. Here's my experience with the issue.

The matrix of a carbide forming steel will range from 1-30 plus percent depending on the alloy. The carbides have no ductility to speak of so they will either fracture or pop out due to stress placed on the edge. The matrix will have it's own ductility depending on it's alloy make up, hardness, and heat treatment. A high alloy matrix will generally be more brittle than a lower alloy matrix. There is a direct correlation between carbon content in the matrix and ductility, the lower the better. Hardness factors into the equation two ways. The higher the carbon content of the matrix, the higher the attainable hardness, thus lower overall ductility. On the plus side, as hardness goes up Tensile and Yield strength increase and this gives the overall system more stability. In a sense it takes more force on the edge to phyically move it. The downside to a high hardness edge is once it moves, it tends to fracture. Picture a drill bit of high speed steel in a vise. It takes a lot of force to start it to yield but once it moves a little it fractures. Take the same diameter of coat hanger wire and it bends over no problem, due to lower hardness and higher ductility.
 
I kinda thought of it like folding sandpaper. With the lower grit stuff the abrasive and adhesive split from the paper at lower angles when you're folding it over to do put it on a block, use it in a corner, etc. The finer the grit, the more I can seem to bend it before the paper splits. You can hear it, 50 grit paper starts to crack at around 90 degrees, where 400 grit is quiet til about 130 (guesstimates) I equated this to edge angles and the forces the steels can withstand because of carbide size, but only because I grew up next to a lot of power lines.
 
hardheart said:
I kinda thought of it like folding sandpaper. With the lower grit stuff the abrasive and adhesive split from the paper at lower angles when you're folding it over to do put it on a block, use it in a corner, etc. The finer the grit, the more I can seem to bend it before the paper splits. You can hear it, 50 grit paper starts to crack at around 90 degrees, where 400 grit is quiet til about 130 (guesstimates) I equated this to edge angles and the forces the steels can withstand because of carbide size, but only because I grew up next to a lot of power lines.
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Actually, I like this explanation a lot. I think it is very applicable here. The effect on an edge is probably even more pronounced because an edge is a three-dimensional system (it has thickness) unlike Sandpaper, which is mostly 2-D.
 
The sand paper comparison is very interesting. Let me throw this out on the ductility vs wear issue. Anyone ever use one of those ceramic blades? I deal with Kyocera on a cutting insert basis but have never used one of their knives. Do those blades handle much for lateral stress? I would think they would have a pretty high tendency to chip out.
 
I have used and seen used several ceramic blades. They are actually pretty strong for normal kitchen chores. But don't drop them on a hard floor. They'll break like glass. A friend had a Boker ceramic folder he used for years to field dress moose and deer and he liked it alot, but he lost it. So I can say with confidence that you can lose a ceramic knife just as easy as steel knife. :)
 
I have some blades full of large carbides (in volume and individual size) and doubt they can take the 5 degree per side edge that Roman, Cliff, and Larrin say can be taken with a lower-carbide steel, but they seem to be able to take a thinner back-bevel with which to hold their thicker final edge. For some, a high hardness seems to explain this, but for others, the hardness is only RC61.
 
I don't think carbide size large or small is going to have an effect on a back bevel/relief.
 
hardheart said:
Considering the actions of some on the forums, phone calls or emails to the facility to somehow 'warn' of Cliff wouldn't be out of the question.
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It happens all the time you should see some of the emails I have seen about me, rumors spread and other nonsense. Some of them have been brought public on Bladeforums several times and I have noted constantly they were a lie.

Several people have claimed to recieve emails from me threating various actions and I gave Cougar and other mods here full permission to ask the site admin where I email for FULL PERMISSION to all of my email information to verify it was a full and outright lie. I also requested to see the emails with full headers and of course none were provided.

But I expected this, you can note it years ago when Bill Martino and I discussed it and then Nemo talked about not reviewing knives which were poor. If the knives did well then he didn't say anything. I even asked makers years ago if they saw someone over hyping their knives and ONE maker (Tichbourne) said he would correct them PUBLICALLY. I did it (still do) and catch a lot of flak, that is to be expected when there is so much hype and misinformation.

I made a firm commitment this year to have a 100% troll filter. I spent a lot of time interacting with very unreasonable people in the past just to see if it could be made productive, mainly as I was interested in the methods. I have a background as a professional mediator (politics mainly, deputy mayor), so it was of interest. As of late I have decided to focus on FACTS about knives which is why I developed the test group and started the website. That is where most of my free time is going now. If people want to learn and read FACTS they can go there. If they want hype and misinformation then that isn't the place for you.

Last Visible Canary said:
....
any quick examples?
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Of the steels, the sandvik series, and the low alloy high carbon japanese cutlery steels. Basically the steels actually made for knives. Kind of ironic that most of the current western ones are not.

thombrogan said:
Of what relation is martensitic hardness to edge stability?
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It is directly proportional.

Would a lower-carbide steel at a similar hardness be better, worse, or the same at resisting plastic deformation and fracture?
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It depends on the edge configuration. If the edge is thick they are more stable, if the edge is thin they are less. There is direct data of this in Landes book. Steels like 154CM (S30V, etc.) are all very poor for example compared to 420HC. Say that on Bladeforums and see what happens, but it is a FACT. Johnston said the same thing years back but he didn't have any fancy equipment.

hardheart said:
I kinda thought of it like folding sandpaper.
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Pretty much, knotty wood also behaves much the same way as high carbide steel in most respects, hard to grind, brittle, etc. .

-Cliff
 
Hi,

I am trying to wrap my mind around ZDP-189 and would like to know the following:

a) Edge angles that it can support without chipping;

b) carbon and alloy content of the matrix;

c) hardness of the matrix;

d) fraction volume of carbides; and

e) carbide size.

Grateful for any information

Regards
FernetBranca
 
Satrang said:
Cliff, you said in your post that you were going to visit PM facilities in the near future. I just asked a simple question as to
when and where. No need to throw a shot in. Answer the direct simple question and move on.
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hardheart said:
He'll probably say so after the fact. Considering the actions of some on the forums, phone calls or emails to the facility to
somehow 'warn' of Cliff wouldn't be out of the question. I doubt he'd like to show up and have an employee greet him with "Such and such told me about
you, tsk tsk. ]
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It’s been over 7 months so answering the question shouldn’t be a problem, unless it is another one of Cliff's lies.
 
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