I Tested the Edge Retention of 48 Steels

Larrin said:
Enchants - https://www.metallographic.com/

You’re going to have to polish the specimens first of course.
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Thanks!

yes on the polish - I've got the materials to do it by hand and won't be doing hundreds of these (fortunately). I just want to get a better look at the actual grains and make sure I'm making *good* chisels and not just pretty ones (and without using commercial heat treat since it's just a hobby). I appreciate the right way to do things (schedules, furnace, etc), but the chisels are sort of a gimmick - everything done by hand and eye.

Thanks for the help. Much of this has been egged on (to make good things rather than just things) by your published information, even though I'm maybe straying far away from the kind of things the book promotes. just the published information about ice water/freezer, etc, terminal improvement has helped me greatly and given a lot more range for acceptable hardness (that being where a chisel is between the strong enough and tough enough endpoints).
 
You won’t easily be able to reveal prior austenite grain boundaries with etching. It’s one of the most difficult things to do with etching.
 
Ahh...am I better off just taking broken (well, I broke them on purpose) samples as i have and doing use tests with the tools?

I'm super pleased with the results that I got with 1095 (and 26c3 is similar) and there is some improvement in the performance of the chisels that match the fine grain. Chisel testing is much like you'd see testing a heavy knife with a mallet on cross grain wood (I know that probably makes little sense as the knife folks like to split kindling.

the objective with chisels is to get something that takes no damage at all (not even under magnification). I guess there's a parallel to razor blades as the same is true - things go south if you can see any deflections under a metallurgical scope and the excellent straight razors will basically show none, while a softer commercial stainless DE blade will show defects pretty readily, presumably due to poor strength compared to a steel that's more like silver steel (bs1407?) or 26c3 in vintage razors.

I will admit that I don't want to learn much about looking at martensite after the steel is tempered - i can extract information out of a 5 minute test with a chisel and a look at the edge under a metallurgical scope. I'm really kind of trying to gauge where my grain fineness is against discussions about grain size after thermal cycling, but if that's not practical with a $500 indian metallurgical scope, that's also a fine answer.
 
Larrin - you mention that finding prior boundaries after converting to martensitic is very difficult. Is there value to me (I'm the heat treater, for better or worse) in snapping the samples and polishing and etching them prior to tempering?

That's what the samples above are, and I've been able to prove that my submagnetic cycling will bring back the coarser samples toward finer - but that's meaningless if it doesn't make a better tool after tempering. Long story short, if I find a way to make tiny grain prior to tempering, I'm assuming that will carry through after tempering, as I've found that to be the case for 26c3 so far (makes a ho hum chisel if just heated quickly, but if cycled, it's about as good as any commercially made chisel that I can find).
 
D-weaver said:
Larrin - you mention that finding prior boundaries after converting to martensitic is very difficult. Is there value to me (I'm the heat treater, for better or worse) in snapping the samples and polishing and etching them prior to tempering?

That's what the samples above are, and I've been able to prove that my submagnetic cycling will bring back the coarser samples toward finer - but that's meaningless if it doesn't make a better tool after tempering. Long story short, if I find a way to make tiny grain prior to tempering, I'm assuming that will carry through after tempering, as I've found that to be the case for 26c3 so far (makes a ho hum chisel if just heated quickly, but if cycled, it's about as good as any commercially made chisel that I can find).
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If you’re breaking the samples you don’t need to polish and etch to see the fracture surface. And if your polishing amd etching you don’t need to break them. Tempering doesn’t affect grain size but it does affect the fracture appearance.
 
Larrin said:
If you’re breaking the samples you don’t need to polish and etch to see the fracture surface. And if your polishing amd etching you don’t need to break them. Tempering doesn’t affect grain size but it does affect the fracture appearance.
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Thank you!! I can see what I can see, and I can check the performance of the tools, but it's nice to know that what I see and observe is relevant.
 
I've been curious about something that perhaps the wizards can help with.

It's reference to aeb-l and its ability to incur scratches.. how is it possible that something so workable maintains an edge?

I had to reshape the spine the other day of one of my favorites in a 300 grit broken in coarse diamond stone and the steel literally melted off as if it were much softer steel (its 61.5 hrc).

So I guess my question is how can a steel thats so workable that scratches (and cleans up) so easily, maintain an edge?

My brain is going full thick forehead trying to figure this out lol.
 
SwissHeritageCo said:
I've been curious about something that perhaps the wizards can help with.

It's reference to aeb-l and its ability to incur scratches.. how is it possible that something so workable maintains an edge?

I had to reshape the spine the other day of one of my favorites in a 300 grit broken in coarse diamond stone and the steel literally melted off as if it were much softer steel (its 61.5 hrc).

So I guess my question is how can a steel thats so workable that scratches (and cleans up) so easily, maintain an edge?

My brain is going full thick forehead trying to figure this out lol.
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There's more than one way to ruin an edge than just wearing it off. Probably will be the case if you're doing more than just cutting paper or cardboard (even that will deflect an edge that's not set up right).

I don't have any AEB-L knives, but I made a couple of plane irons (blades) for woodworking, and they have lasted about 1.5-1.7 times as long as O1 or 52100 (plane blades in an idealized test are a very good way to test wear

https://imgur.com/neyObEz

(that's the picture of a plane iron once it's run out of clearance and stopped cutting - notice no damage to the edge. Magnification is 150x with a legitimate top lit scope (vs. the magnification claimed with a lot of inexpensive hand held scopes). Edge length in the picture is about 2 hundredths of an inch.

At any rate, AEB-L doesn't have large carbides in it and it especially doesn't have large carbides that are unfriendly to sharpening, but a lot of the wear that you put on an edge isn't going to be metal on metal or metal on sand where you need vanadium or neutron star carbides.

Long story short, I have a use test - twice - planing 3500 feet of wood that confirm's larrin's finding, even with suboptimal (forge) heat treat. I was also pleasantly surprised to find that AEB-L is easily sharpened around c60 on oilstones without strange edge nits on a washita like you can get polishing the apex with A2 or D2.
 
Larrin said:
Recently I was able to acquire a used CATRA machine, so I heat treated just about every knife steel I had, made 57 knives with the help of knifemaker Shawn Houston, and tested them all to see which cut the longest. For a few of the steels I did multiple heat treatments to look at a couple variables and to see the effect of hardness. I also compared edge retention and toughness to see which steels have the best balance of properties. https://knifesteelnerds.com/2020/05/01/testing-the-edge-retention-of-48-knife-steels/
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Holy cow, that is some research right there and the depth of information provided is crazy. Great Job!
 
Your compendium of edge retention is amazing.
Do you have the desire to do the same attention to retention to other traits like toughness, edge stability and corrosion?
Will you be the steel Moses or Messiah?
 
Fir Na Tine said:
Your compendium of edge retention is amazing.
Do you have the desire to do the same attention to retention to other traits like toughness, edge stability and corrosion?
Will you be the steel Moses or Messiah?
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I've done as much or more testing of toughness as I have edge retention, a bunch of it is summarized in the edge retention article. Corrosion resistance testing I also have a handful of articles about.
 
evilgreg said:
Wow, this is pretty awesome. Thanks for the great read. One of the things that always made me question other edge retention test results I've seen was the number of uncontrolled variables, some of them massively important (e.g. basic geometry).
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Agreed. Very cool.
 
post removed...sorry, didn't anticipate links to pictures with a question would automatically embed the pictures making a huge distracting post.
 
separate question for larrin - have you ever tested a steel that seems to hold up to the catra test without issue even if it's untempered? We do what would be more like push test for planing in woodworking, and I just made a 52100 plane iron and wasn't satisfied with its toughness (too much isn't good for woodworking, strength is more important), It seems to hold up fine untempered aside from being a pain to sharpen on normal abrasives.
 
Untempered steels would show issues in other areas it would probably be fine with the CATRA test.
 
I’ll have to have a fresh look, but I want to see the comparison between dendritic cobalt and other cast steels against nominal and CPM steels.
 
Larrin's book is extremely thorough, well written, contains data sets you couldn't wrestle from the steel makers, and is a bargain for knife enthusiasts and knife makers (forgers or stock removal types). It's a true gem, and a real blessing to have in our industry.

Highly recommended for knife enthusiasts and ALL makers, no matter the skill level.

I will buy all future revisions of this fantastic book.

Larrin, congratulations... you've provided a foundation from which others can learn, stand taller, and reach higher.
 
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Fir Na Tine said:
I’ll have to have a fresh look, but I want to see the comparison between dendritic cobalt and other cast steels against nominal and CPM steels.
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Larrin has a description of "knives" that he tests here toward the bottom. If you send him knives and samples in that configuration made out of the materials of your interest he will most likely add them to his testing if he has bandwidth to do it.
 
Have you ever tested M35-HSS at around 62-64RC for a knife application ?
 
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