Don't know about Elmax

cncpro11 said:
So which is it? Spreading to other companies and no longer isolated to KAI or thoroughly debunked?
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That's for you to decide for yourself, because no hard evidence has been provided proving, or disproving either theory.
 
cncpro11 said:
So which is it? Spreading to other companies and no longer isolated to KAI or thoroughly debunked?
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For someone who has been very outspoken against our ZT brand, I appreciate you taking the time here in this thread to ask questions and add commentary.

Burnt edges seem to be a very random event that has happened (apparently in some cases), that seems has caught some attention here on the forums. As with many topics like these, it's been tried to be made more than it is.

Really a non-issue in our eyes.

We've already addressed Elmax. Good steel in our eyes.
 
Thanks for that. You should note that my outspokenness is more from an ergonomic standpoint and never because of the quality of your blade steel or other materials.
Like I said earlier, I think the whole burnt edge thing is quite ridiculous and for good reason.
I have seen powdered metal drills literally cook to cherry red when they hit a hard spot or cant get coolant to the tip and yet drill several holes afterwards with no ill effect. I honestly think that burning an edge simply from sharpening enough to ruin the heat treat is just plain silly.
 
jmho, it takes seconds for powered sharpener to cook an ELMAX edge to 500-600F, thereby quickly reduced the edge hardness to 55RC where it won't support sub 40* inclusive bevel.

cncpro11 said:
Thanks for that. You should note that my outspokenness is more from an ergonomic standpoint and never because of the quality of your blade steel or other materials.
Like I said earlier, I think the whole burnt edge thing is quite ridiculous and for good reason.
I have seen powdered metal drills literally cook to cherry red when they hit a hard spot or cant get coolant to the tip and yet drill several holes afterwards with no ill effect. I honestly think that burning an edge simply from sharpening enough to ruin the heat treat is just plain silly.
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When Elmax first came out it was said to be almost impossible to chip and after a few years of carry I have yet to see anything close to a chip. My brother has a 0350 composite Elmax and dropped it on concrete from about 3 ft off the ground and it only had minor rolling, I have used and abused my 0551 sense the day it came out and never had a single issue.

I can tell my first run is a bit softer than the 0560's I have sharpened but it still performs great and is nothing I'm real worried about. Burnt edges? Hogwash... That's a poor excuse for someone that does not know what they are talking about.
 
Carnage1 said:
I'm a plumber so if i forgot lets say my razor in truck and i needed to open a water heater box (open not break down) after doing 2 the steel wouldn't cut paper. I could strop back most times after 4-5 light runs. After this went on for few months i reprofiled edge 40 convex it cut better but still dulled fast. There are these long thin plants that grow real tall in backyard so i would cut those to compare how long the edge would hold. Simple things like that that a knife for military or law enforcement would be expected to shrug off. Like i said I'm getting a new blade from ZT so i hope this will at least give me the performance i have from my other knives.
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So after a few swipes through cardboard, it wouldnt cut printer paper? Not with a slice or anything? Ifthats the case, something was definately off. Any chance of an update after the new blade arrives?
 
Not a scientific study, but out of curiosity I just made 10 long cuts on a cardboard box with my ZT 0560 with Elmax. It cut printer paper perfectly before the cardboard cutting and still cut the printer paper perfectly afterwards. I still love my Elmax 0560!
 
bluntcut said:
jmho, it takes seconds for powered sharpener to cook an ELMAX edge to 500-600F, thereby quickly reduced the edge hardness to 55RC where it won't support sub 40* inclusive bevel.
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I don't understand how an opinion proves a drop to 55rc when there was no test before or after? :confused: 2 questions, How do you know where it started at (Numerical rc #), and how do you know it has dropped to 55rc? If you could provide the evidence for this, I'm sure I would be able to completely understand.:thumbup:
 
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bad_juju said:
I don't understand how an opinion proves a drop to 55rc when there was no test before or after? :confused: 2 questions, How do you know where it started at (Numerical rc #), and how do you know it has dropped to 55rc? If you could provide the evidence for this, I'm sure I would be able to completely understand.:thumbup:
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93.1% of all statistics are made up on the spot :)
 
bad_juju said:
... I'm sure I would be able to completely understand.:thumbup:
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This stuff neither statistics nor lucks. Just look at the tempering chart for Elmax. If an apex area hits 500-600F, I expect rc to drop from whatever above toward 55-ish. unless the original rc is below 55 already, in that case hrc won't change. Does the hrc number absolute? nope, realistically it deviates a few points depend on hi-temp exposure time & how the blade was ht. Easy to try this with most steels, just use a dull fine grit slack belt for a couple seconds on a small section of your knife edge, a good chance you can see the difference between that section and other section.
 
bluntcut said:
This stuff neither statistics nor lucks. Just look at the tempering chart for Elmax. If an apex area hits 500-600F, I expect rc to drop from whatever above toward 55-ish. unless the original rc is below 55 already, in that case hrc won't change. Does the hrc number absolute? nope, realistically it deviates a few points depend on hi-temp exposure time & how the blade was ht. Easy to try this with most steels, just use a dull fine grit slack belt for a couple seconds on a small section of your knife edge, a good chance you can see the difference between that section and other section.
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I'm not a metallurgy expert at all, but I can read charts. The elmax tempering graph in the spec sheet says the data is for a 2-time temper, holding the temp for 2hrs each time. I don't see how the act of sharpening of any manor relates to this chart. I wouldn't even begin to know how any relevant rc data could be extracted from it.

It seems to me that much of the negative discussion of elmax is anecdotal (no scientific evidence or method).
 
If only El Max, the conquistador, was here to defend his honor. :)

People buy in too much into what the vocal minority say.
 
Nothing wrong with Elmax, I found the steel easy to work with (vs cpm-m4, 3v, etc.), polish up nicely and plus good edge retention.

My point is if the edge is over heated even for a second, one should expect that edge roll more easily for lower bevel angle. Wanna try this anecdotal? touch a well sharpened apex to a stove top surface at 60-80% powered for 1 or 2 seconds. Make a handful cardboard cuts then let's see if that edge would still smoothly cut newsprint or even printer paper.
 
coiledwire said:
I'm not a metallurgy expert at all, but I can read charts. The elmax tempering graph in the spec sheet says the data is for a 2-time temper, holding the temp for 2hrs each time. I don't see how the act of sharpening of any manor relates to this chart. I wouldn't even begin to know how any relevant rc data could be extracted from it.

It seems to me that much of the negative discussion of elmax is anecdotal (no scientific evidence or method).
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any steel can suffer this fate, especially steels that temper at lower temperatures.

it just takes a few moments lingering on an edge to hit those kind of temperatures. there are many people who know much more about metallurgy, heat treating, and sharpening than I who consider nearly every power sharpened factory edge to be sub par because of the temperatures reached upon sharpening.

either way, this only affects the very surface steel and can be sharpened away. an edge doesn't have to be "burnt" to be overheated during sharpening.
 
I rolled a 30-degree inclusive 551 (first run) on the bone of my index finger. Before that, it went through just about everything else, including the nail and the callused skin of the fingertip.

Note to self - never trust a detent to hold a blade closed. Second lesson - knives do not like to share pockets with keys and other crap.

Still cuts like a mother*. Taken through sandpaper progression 400 to 1200, finished with CrO strop. Not sharpened enough to have gotten past any factory annealing from power sharpening, but it doesn't seem to have suffered that issue anyway.
 
coiledwire said:
I'm not a metallurgy expert at all, but I can read charts. The elmax tempering graph in the spec sheet says the data is for a 2-time temper, holding the temp for 2hrs each time. I don't see how the act of sharpening of any manor relates to this chart. I wouldn't even begin to know how any relevant rc data could be extracted from it.

It seems to me that much of the negative discussion of elmax is anecdotal (no scientific evidence or method).
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I pose the following question: Those temperatures for what thickness? You have to alter your heat treat depending on the thickness of your blade. That is why makers have started heat treating blades at stock thickness to get an even and proper heat treat response throughout the blade rather then differential (differential though still has its place dont get me wrong but needs to be done correctly as well).

Lets assume a maker has his knives water jetted, standard thickness of Elmax and then sent of for hardening.

Now from:

www.uddeholm.com: HPS_Steel_for_knives

There are a few things to consider even before hardening such as removing the stainless capsule material on the surface of Elmax. This can actually result in a lower hardness if not removed properly.

Now the maker has done all of this, heat treated his blades accordingly and now wants to start grinding since Bohler states: "This means that the final grinding can be done after hardening, eliminating heat treatment related risks such as distortion and surface decarburization" Page 7 of the linked article above.

So the next thing that has been debated for some time is "burnt edges".....really? How is it possible?

Well, lets see what Bohler has to say in their Grinding of Tool Steel PDF

"Incorrect grinding of a hardened tool
steel can result in such a high temperature at the ground surface that
the tempering temperature of the
material is exceeded. This results in a
reduction in the hardness of the surface. If the temperature is allowed to
rise further, the hardening temperature of the material can be reached,
resulting in rehardening. This produces a mixture of non-tempered
and tempered martensite in the surface layer, together with retained
austenite, as shown in Photo 3. Very
high stresses arise in the material,
often resulting in the formation of
cracks" Page 11.

"Incorrect grinding, resulting in a
modified surface layer, often reveals
itself through burn marks—discoloration of the ground surface. In order
to avoid burning and grinding cracks,
it is necessary to keep down the
temperature of the ground part, e.g.
bymeans of good cooling, and to
employ properly dressed grinding
wheels that cut the material with
sharp cutting edges instead of simply
generating heat through friction." Page 12.

So for me it stands to reason, if there is no care taken in post hardening grinding a maker can really screw up a steel, no matter how "super" that steel might be.
 
I agree that super-steels != indestructible, and that grinding can heat metals to the point where their properties change at the surface. The last part of the spec reference said there can be signs of improper grinding thru discoloration and/or cracks. Has anyone reported to have these visual signs from a stock blade?
 
marthinus said:
"Incorrect grinding of a hardened tool steel can result in such a high temperature at the ground surface that the tempering temperature of thematerial is exceeded. This results in a reduction in the hardness of the surface.
In order to avoid burning and grinding cracks, it is necessary to keep down the temperature of the ground part, e.g.
by means of good cooling, and to employ properly dressed grinding wheels that cut the material with sharp cutting edges instead of simply generating heat through friction." Page 12.

So for me it stands to reason, if there is no care taken in post hardening grinding a maker can really screw up a steel, no matter how "super" that steel might be.
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Ain't it great when someone actually brings something solid to the table?
Isn't that why we buy cooling oils from Sears when we are grinding tools on the workbench?
Thank you, Marthinus for the reference material quotes. It seemed to be necessary here. Speculation be damned.
Sonnydaze
 
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