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What steel can take the thinnest edge with chipping or rolling
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BluntCut MetalWorks
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If I rephrase OP question as:
Tasks = Normal/casual cutting 20 times per 1/8" wide ziptie, 3/16" thick 8" long cardboard, whittle + light chop seasoned ebony, whittle dried beef rib bone.
With starting apex radius = ~0.5um at 13dps edge bevel
After performed tasks above - Which steels will retain apex radius(at widest spot) thinner than 1.5um?
IMHO - all steels with carbide dia > 1.5um won't get on this list. Same go for steels with hrc below 63. IME - candidate steels with great ht could qualify for this list includes: 1084,1095,52100,W2,O1 and a few more ultra fine grain & carbide steels...
The list would be much larger if criteria for final apex radius is 3um or less.
Tasks = Normal/casual cutting 20 times per 1/8" wide ziptie, 3/16" thick 8" long cardboard, whittle + light chop seasoned ebony, whittle dried beef rib bone.
With starting apex radius = ~0.5um at 13dps edge bevel
After performed tasks above - Which steels will retain apex radius(at widest spot) thinner than 1.5um?
IMHO - all steels with carbide dia > 1.5um won't get on this list. Same go for steels with hrc below 63. IME - candidate steels with great ht could qualify for this list includes: 1084,1095,52100,W2,O1 and a few more ultra fine grain & carbide steels...
The list would be much larger if criteria for final apex radius is 3um or less.
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Thanks Bluntcut
All carbon steel?
Does that mean the chromium carbides are too massive unless kept in check like AEB-l with limited carbon or limited chromium in tool steel?
Also could you elaborate on the apex width and carbide diamter?
Fascinating info!
Much to learn!
I used 1055 in the mid 50s HRc. It was a reground Cold Steel Barong machete.
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BluntCut MetalWorks
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Not all carbon - just those with Cr below 2% and with grain optimized alloys (small amt of ea elements) added and carbon between 0.85% to 1.2%. Crucial that ht must produce strong working (63+rc) blade - combination of ultra fine grain, interlocking lath martensite, clean+tight grain bounaries, RA < 2%, carbide dia < 0.3um.
Good ht aebl Cr7C3 are quite small (0.5-0.2um) and with only about 2-3% carbide volume, so if its working hardness 64-65rc then it's possible to have final(after tests) apex below 1.5um. D2,A2 and all PM steels (maybe except zfinit) carbides are mostly larger than 1.5um along with higher carbide volume, together isn't conducive to thinnest possible final apex.
Apex is more like a ridge than a line, so apex width is edge thickness at the shoulder of the mount/flat-top (100-300nm from peak).
Most carbide has spheroid and oblong shape with irregular boundaries - its diameter is the longest distance from one side to the other side. e.g. the longest line fit inside a rock, that is its diameter (in worse case scenario).
*since 3V is lately been popular: 3V with around 2.5-2.8% carbide volume and carbide dia 2+um, so whittle bone & light chop ebony would broaden the final apex toward 2-3um even for 3V at 64rc.
Good ht aebl Cr7C3 are quite small (0.5-0.2um) and with only about 2-3% carbide volume, so if its working hardness 64-65rc then it's possible to have final(after tests) apex below 1.5um. D2,A2 and all PM steels (maybe except zfinit) carbides are mostly larger than 1.5um along with higher carbide volume, together isn't conducive to thinnest possible final apex.
Apex is more like a ridge than a line, so apex width is edge thickness at the shoulder of the mount/flat-top (100-300nm from peak).
Most carbide has spheroid and oblong shape with irregular boundaries - its diameter is the longest distance from one side to the other side. e.g. the longest line fit inside a rock, that is its diameter (in worse case scenario).
*since 3V is lately been popular: 3V with around 2.5-2.8% carbide volume and carbide dia 2+um, so whittle bone & light chop ebony would broaden the final apex toward 2-3um even for 3V at 64rc.
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Let me get some pics brother
Whoa, I need to process this to fully understand
Intense.
Thanks Bluntcut
How about a video. Notice that is dry wood that's been in my wood pile for a couple of years, very hard. Most of what I cut with it is smaller and green, so the sticking is much less.
https://www.youtube.com/watch?v=FTXH1U8IuU8
I should have asked that differently
I would expect you not to have any issues with it.
What I'm trying to get at is - what is your opinion on the average user sharpening it as compared to say a carbon steel?
Assumption being that the average user is not an expert sharpener....
there's many variables here, I realize that.
I'll chime in on this as well. I have have found 10V to be MUCH easier to sharpen than a carbon steel. You don't have to chase a burr, you can simply get a nice crisp edge in a matter of minutes. I use diamond stones, and it takes hardly any time at all.
IMO, the myth of soft steels being easier to sharpen is just that, a myth.
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wouldn't this extend to most of the sandvik steels as well? I know that 12C27, 13C26 and the like are very fine grained and are very tough because of it.
chiral.grolim
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13C26 is the same as AEBL (0.68% C), and 12C27 is the lower carbon cousin (0.6%). Recommended HT of 13C26 puts hardness ~60 Rc, for 12C27 ~57 Rc, both with ~15% RA.
Note that Bluntcut is recommending carbon 0.85 - 1.2%, with final hardness >63+ Rc, and <2% RA.
He is also the only person I have seen testing AEBL at >61 Rc, and he also tests D2 at high hardness (considered a 'brittle' steel due to the high carbide content and normally poor distribution). If you haven't been following his work, there is a thread on it here: http://www.bladeforums.com/forums/showthread.php/1367516-BCMW-s-ht-chopping-impact-tests/page9
Bluntcut wants to make steels as close in hardness to ceramic as possible for the highest strength (greatest edge stability against the folding/compression that creates stress-risers resulting in failure) while retaining sufficient toughness to endure use at an efficient cutting geometry (e.g. 12-15 dps apex, with 20-dps micro if necessary).
Keep in mind that the HIGHEST edge-stability is achieved by the HARDEST materials (i.e. carbide) but the material can be very brittle (poor choice for certain types of use) and requires careful preparation to ensure a stable geometry for the intended use (e.g. toothy edges may be too thin/fragile).
The sandvik steels are purported to be very fine grained, but I have yet to come across actual charpy data demonstrating toughness. Hitachi makes a Japanese version of 13C26 as well (VG-2). Keep in mind that it is "low end steel" from manufacturers, primarily produced as strip-steel for disposable razors blades, though it is popular with some makers of kitchen knives. VG-2 is sometimes used as the outer laminate in blades. These steels are not commonly seen in larger blades, despite having been around for many decades. 420HC (somewhat lower carbon than 12C27) is found in some lines of large 'survival' blades an machetes, e.g. Condor uses it in certain models but HT'd to around 53 Rc = very poor edge-holding. None of this means that the sandvik steels are not excellent performers and make great knives, but I have read more subjective than objective information regarding them. 12C27 and 13C26 should each be a step up from Buck's 420HC in terms of strength and wear-resistance, but not necessarily in terms of fracture toughness, and most users may not see a difference between Buck's 420HC and another's 13C26 at the same geometry, except that the 13C26 is less stain-resistant. *shrug*
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The only fine grained, low carbide steel similar to Sandvik steels that I have come across where impact energy data is given is Cronidur 30.
At around 59HRC impact energy is around 60J. That is significantly higher than S35VN as an example but still below something like CPM-3V. The data sheets however on Cronidur 30 do not tell the full story though (as if any data(marketing) sheet does). There is a patent on Cronidur 30 where after tempering HRC was measured as 64HRC. Would love to test it in that area.
chiral.grolim
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Cronidur 30 is not really like 13C26 or even 12C27 - it has only 0.3% carbon akin to 420J2 with a bit of moly added and 0.3 - 0.5% Nitrogen as a carbon replacement, which requires very high pressure processing to manufacture. According to the manufacturer specs, its working hardness is 54 Rc wherein it achieves the desired high toughness making it suitable for roller bearings. 62 would be the expected as-quenched hardness, hard to imagine 64. The spec-sheet mentions that the chromium carbonitrides are between 6 and 40 microns. I am not sophisticated enough to give a carbide volume estimate, but it would not surprise me if it was in the same range as 420HC and present roughly the same qualities. Toughness of 60J at 59Rc according to what test? Izod or v-notch Charpy? I would guess that it is an un-notched test. Please understand, I am not saying it isn't tougher than S35VN, it should be tougher given the lower carbide volume, but I again doubt it would perform any differently than Buck's 420HC.
http://www.progressivealloy.com/pdf/cronidur30.pdf
For reference, here is Crucible's data sheet for A2 tool steel: http://www.crucibleservice.com/eselector/prodbyapp/tooldie/airkoolt.html
1% carbon, as-quenched hardness 64 Rc, Charpy C-notch toughness 56J at 60Rc. 420-steel can achieve that level of toughness no problem... but at much lower hardness (e.g. 54 Rc) that is sub-par for holding thin apex geometry.
If Cronidur 30 or 13C26 or 12C27 or 420HC can behave like A2 in terms of attainable hardness and toughness, then they should have been in use in high-end chisels long ago...
A stainless steel at 64Rc with the toughness of A2... that would be awesome indeed :thumbup:
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Chiral,
Your post#33 about Bluntcut works is better said than what I intended to say.
@ DBH,
I'd say your question is Bluntcut's quest. Check his work and posts & videos. You'd enjoy it!
Your post#33 about Bluntcut works is better said than what I intended to say.
@ DBH,
I'd say your question is Bluntcut's quest. Check his work and posts & videos. You'd enjoy it!
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Chiral, I love your post, #33. That third line....."Keep in mind....." DEAD ON THE MONEY. That has been my conclusion with reference to apex stability/edge retention. Harder is better, and carbides help that. There is a point where the carbides which help the overall hardness of the matrix may be too big, or too many, for the intended job at hand. Sweet spot=high matrix hardness x (carbide % + carbide size) / the intended use!
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I dont know what impact test was done. Wish I knew.
Those "specs" are more general than anything else. You know that.
Checked the patent again and HRC of two housings are 63 and 65 after tempering.
Sure specs in the marketing data says working hardness of 54. Working hardness for N690 is not 63-64 according to "specs" but with some experimentation Blunt Cut got it there.
You are right that it is not like 13C26 or 12C27. But closest I have found to 14C28N with some other added info.
Cronidur 30 is moving beyond mere rolling bearings into fasteners for Boeing etc. On a project I am involved in we are looking into it as fasteners within saline water. Interesting stuff.