Of course its nice to have a hard knife.
Discuss

Not bashing you, and maybe im treating my rex45 pm2 harder than my beloved Cruwear one. But also Ankersons cutting tests show the softer s110v military way above the harder Rex45 one. Why ?Pelagic wrote: ↑Sat Jun 15, 2019 10:06 pmI find it hard to believe that Rex 45 at 66 HRC has noticeably less edge retention than cruwear at 61-62 HRC. That is an extreme difference in hardness.
I know HRC isn't everything, so whoever is waiting to bash me as if I believe that, calm down. But cut tests almost always reveal that HRC and edge retention are directly correlated.
Yup. Well said.Deadboxhero wrote: ↑Sat Jun 15, 2019 10:41 pmEdge finish and cutting style.
220- 400 grit with a draw slicing motion
More of the harder carbides are exposed with a rougher finish at the teeth of the edge.
Take s110v and Jack it to 65 with a boutique HT and you'll smoke the softer s110v.
So hardness has a place for edge performance
A stronger matrix holds the carbides better also.
So harder matrix can support thinner blade grinds and support thinner edges angles but is an inverse relationship with pure durability.
So either use a knife like a knife and be rewarded with more performance. Or use like a hammer and be punished with thicker geometry that doesn't cut very good but doesn't break for ridiculous non knife uses
Well, yeah, well said; except - this might be entirely me - I missing an answer to my question. I am comparing two knives with identical geometry in practical use (PM2), wasn't using them as hammer or prybar. Cutting greens in the yard, a few boxes for recycle, cutting electrical cables and getting rid of isolation, cutting brass connectors out of a hose, etc. After a day like that I have to resharpen the Rex45 PM2, the Cruwear one holds a couple yard days instead. I had a Cruwear Manix 2 camping for a week, and the edge did not reflect light on our return.Deadboxhero wrote: ↑Sat Jun 15, 2019 10:41 pmSo either use a knife like a knife and be rewarded with more performance. Or use like a hammer.
HRC is matrix hardness. A given sample, within a useful range of hardness, will gain wear resistance with higher hrc. But, comparing two compositions, that hardness won’t necessarily overcome carbide. Carbides are the difference, here. That’s what Deadbox Hero was alluding to. (See also: nitrides)ferider wrote: ↑Sun Jun 16, 2019 9:29 amWell, yeah, well said; except - this might be entirely me - I missing an answer to my question. I am comparing two knives with identical geometry in practical use (PM2), wasn't using them as hammer or prybar. Cutting greens in the yard, a few boxes for recycle, cutting electrical cables and getting rid of isolation, cutting brass connectors out of a hose, etc. After a day like that I have to resharpen the Rex45 PM2, the Cruwear one holds a couple yard days instead. I had a Cruwear Manix 2 camping for a week, and the edge did not reflect light on our return.Deadboxhero wrote: ↑Sat Jun 15, 2019 10:41 pmSo either use a knife like a knife and be rewarded with more performance. Or use like a hammer.
And, from https://www.bladeforums.com/threads/ran ... ope.793481
CPM S110V - 1080 - Spyderco Military - 63-64 RC - .020" Behind the edge
: : :
REX-45 - 840 - Spyderco Military - (? HRC) - .023" behind the edge
From viewtopic.php?f=2&t=83847
REX45 Military - (66.3 - 67) HRC (at least 2 Rockwell points higher than the s110v Military, but wear resistance is 25% lower).
What's up with that ? What does that have to do with anybody using a knife not as a knife ?
Roland.
Thanks, got it. So M4 or even M2 at - say - 64 can have similar or more wear resistance than Rex45 at 67, as M[24] have more carbides ?Banter 247 wrote: ↑Sun Jun 16, 2019 10:01 am
HRC is matrix hardness. A given sample, within a useful range of hardness, will gain wear resistance with higher hrc. But, comparing two compositions, that hardness won’t necessarily overcome carbide. Carbides are the difference, here. That’s what Deadbox Hero was alluding to. (See also: nitrides)
So... LC200N at 58 will smoke AEB-L at 60, assuming the same geometry, because LC200N is leaning on nitrides, while AEB-L read about carbides in a book in a long, hot summer around 1973.
I wonder in what context they were making that statement. In folding knives (edge retention), I'd seriously doubt that was the case. There's not a big enough difference in those 2 steels carbide-wise to overcome that huge difference in matrix hardness.
I’m not especially familiar with Rex 45 or Cruwear.ferider wrote: ↑Sun Jun 16, 2019 10:06 amThanks, got it. So M4 or even M2 at - say - 64 can have similar or more wear resistance than Rex45 at 67, as M[24] have more carbides ?Banter 247 wrote: ↑Sun Jun 16, 2019 10:01 am
HRC is matrix hardness. A given sample, within a useful range of hardness, will gain wear resistance with higher hrc. But, comparing two compositions, that hardness won’t necessarily overcome carbide. Carbides are the difference, here. That’s what Deadbox Hero was alluding to. (See also: nitrides)
So... LC200N at 58 will smoke AEB-L at 60, assuming the same geometry, because LC200N is leaning on nitrides, while AEB-L read about carbides in a book in a long, hot summer around 1973.
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It depends on how they were sharpened. The Rex 45 and Cruwear are close but the Rex45 is run harder.ferider wrote: ↑Sun Jun 16, 2019 9:29 amWell, yeah, well said; except - this might be entirely me - I missing an answer to my question. I am comparing two knives with identical geometry in practical use (PM2), wasn't using them as hammer or prybar. Cutting greens in the yard, a few boxes for recycle, cutting electrical cables and getting rid of isolation, cutting brass connectors out of a hose, etc. After a day like that I have to resharpen the Rex45 PM2, the Cruwear one holds a couple yard days instead. I had a Cruwear Manix 2 camping for a week, and the edge did not reflect light on our return.Deadboxhero wrote: ↑Sat Jun 15, 2019 10:41 pmSo either use a knife like a knife and be rewarded with more performance. Or use like a hammer.
And, from https://www.bladeforums.com/threads/ran ... ope.793481
CPM S110V - 1080 - Spyderco Military - 63-64 RC - .020" Behind the edge
: : :
REX-45 - 840 - Spyderco Military - (? HRC) - .023" behind the edge
From viewtopic.php?f=2&t=83847
REX45 Military - (66.3 - 67) HRC (at least 2 Rockwell points higher than the s110v Military, but wear resistance is 25% lower).
What's up with that ? What does that have to do with anybody using a knife not as a knife ?
Roland.
I’m unsure of how they express *wear resistance* in machining and industrial application, but in the context of cutlery, M4 at 63 will out perform 20CV at 58 in terms of edge retention vs cardboard or similar commonly cut media.
True and point taken.
That's what I find kind of funny about the recent M390/20CV/204P uproar. It doesn't seem to have been sparked by people upgrading from VG10 or 14C28N or S30V and not being happy in use, but from repeated cardboard cut tests. Doesn't mean the tests are bad or worthless, just that they might not be representative of how some people are using knives in those steels day-to-day (that, or no-one's actually using them... separate issue
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