Here are three of the hardest, strongest, most wear resistant ferrous metals available in knife sizes on the planet that can be rolled into flat bar.
CPM 15V, Maxamet, and Rex121
Rex 121 is the most difficult steel I've ever ground.
The Maxamet is prone to warping.
15v is not as difficult to grind as Rex 121 and not as prone to warping like Maxamet
Re: Sal, Can we get CPM 15v?
Posted: Sat Jun 08, 2019 12:35 pm
by The Mastiff
Rex 121 is like having one of the T series steels ( or Maxamet) then adding 10V. It's a real monster. I can see it being a PITA. Not many knifemakers will work with it.
Rex 121 is like having one of the T series steels ( or Maxamet) then adding 10V. It's a real monster. I can see it being a PITA. Not many knifemakers will work with it.
joe
It's very expensive to make a nicely finished knife out of with thin geometry.
This micrograph work Larrin has done is incredible. It is such a fascinating and informative window into all the different steels. I don't think this project has been appropriately received, or it's magnitude and importance appreciated yet. Maybe it's because of his understated, matter of fact manner of presenting it, like ho hum, just another weekly article. I should probably go hit up his patreon.
This micrograph work Larrin has done is incredible. It is such a fascinating and informative window into all the different steels. I don't think the reaction to this project has been appropriately received and appreciated yet. Maybe it's because of his understated, matter of fact manner of presenting it, like ho hum, just another weekly article. I should probably go hit up his patreon.
Yeah, man, every little donation basically goes towards advancing the knife community as a whole. The last wave of pateron funding allowed Larrin to buy all the metallography equipment needed to polish, mount and etch these pictures.
It's some tedious and boring work processing samples, very meticulous and thankless. I gladly support his work monthly.
The reason why these pictures are so important is that before this article, there wasn't anywhere near this many knife steel micrographs processed with the same etching and polishing and with the same magnification to draw conclusions from.
So it's a worthy cause.
Re: Sal, Can we get CPM 15v?
Posted: Sat Jun 08, 2019 11:30 pm
by The Mastiff
It's very expensive to make a nicely finished knife out of with thin geometry.
I'd think it was. Expensive steel, high quality belts changed more often, etc. You always seem to be striving for higher performance which is why you will work with these super high performing steels in the near tungsten carbide class. If you had assembly lines putting out 30 knives per month to pay the bills that steel wouldn't be your first choice to work with.
You are in a great position to make your own mules to test while controlling the variables and can make actual comparisons of the different steel. That's pretty cool.
It's very expensive to make a nicely finished knife out of with thin geometry.
I'd think it was. Expensive steel, high quality belts changed more often, etc. You always seem to be striving for higher performance which is why you will work with these super high performing steels in the near tungsten carbide class. If you had assembly lines putting out 30 knives per month to pay the bills that steel wouldn't be your first choice to work with.
You are in a great position to make your own mules to test while controlling the variables and can make actual comparisons of the different steel. That's pretty cool.
Thanks Joe.
Re: Sal, Can we get CPM 15v?
Posted: Sun Jun 09, 2019 3:51 am
by Deadboxhero
Ground out the 15v, this protocol is the hardest one so far, +67rc range.
I Set the edge with CBN/Diamond waterstones. The ceramic belts would damage the apex when a steel that has this much carbide volume and hardness by causing fatigue from burnishing and heat from friction.
Re: Sal, Can we get CPM 15v?
Posted: Sun Jun 09, 2019 5:31 am
by Woodpuppy
My forearms and hands hurt just thinking about it. Bet you have a helluva handshake!
My forearms and hands hurt just thinking about it. Bet you have a helluva handshake!
Re: Sal, Can we get CPM 15v?
Posted: Sun Jun 09, 2019 5:51 am
by Deadboxhero
Went back to the grinder and thinned out the blade.
With such a high HRC it can support a thinner geometry than the previous temper at 64rc when used properly to cut stuff.
Re: Sal, Can we get CPM 15v?
Posted: Sun Jun 09, 2019 6:26 pm
by Deadboxhero
Edge stability testing with the higher hardness and thinnest geometry just to see what happens at the limit.
Before, we tested at 0.009"bte and had deformity due to lack of Strength at 64rc for that given geometry.
Turned the volume dial to the max to see what happens for the sake of finding the limits with this new stability focused protocol now tempered to +67rc
Yes it's interesting to see how everything works in concert between hardness and geometry in such an extreme steel. Should help put some details into context and connect the dots for some on how edge performance works and the trade offs involved. It's a vast and difficult subject to get into I find.
Yes it's interesting to see how everything works in concert between hardness and geometry in such an extreme steel. Should help put some details into context and connect the dots for some on how edge performance works and the trade offs involved. It's a vast and difficult subject to get into I find.
There are so many layers to the equation. At first blush (to me) it might seem like higher hardness would lead to less edge stability. That's actually amazing that such a high carbide steel at that hardness with incredibly thin edge geometry can take that kind of hard use and not suffer serious damage.
Now I'm curious how Maxamet would fare in an apples-to-apples comparison. It's got similar carbide volume to CPM 15V (perhaps with more tungsten and less vanadium carbide.) Spyderco's heat treat with Maxamet is geared toward high hardness - up to 69 HRC - so shouldn't it have similar edge strength to CPM 15V?
Oh and how about CPM REX 121? :D
BBB I know I've said this before but thanks for your contributions to knife geekdom. Between you and Larrin Thomas I am learning more than I ever could've imagined about knife metallurgy. You guys are the best! :cool:
Yes it's interesting to see how everything works in concert between hardness and geometry in such an extreme steel. Should help put some details into context and connect the dots for some on how edge performance works and the trade offs involved. It's a vast and difficult subject to get into I find.
There are so many layers to the equation. At first blush (to me) it might seem like higher hardness would lead to less edge stability. That's actually amazing that such a high carbide steel at that hardness with incredibly thin edge geometry can take that kind of hard use and not suffer serious damage.
Now I'm curious how Maxamet would fare in an apples-to-apples comparison. It's got similar carbide volume to CPM 15V (perhaps with more tungsten and less vanadium carbide.) Spyderco's heat treat with Maxamet is geared toward high hardness - up to 69 HRC - so shouldn't it have similar edge strength to CPM 15V?
Oh and how about CPM REX 121? :D
BBB I know I've said this before but thanks for your contributions to knife geekdom. Between you and Larrin Thomas I am learning more than I ever could've imagined about knife metallurgy. You guys are the best! :cool:
The Maxamet Manix 2 I had was more than twice as thick behind the edge than this CPM 15V knife at 0.022" bte and still not as stable even though very strong.
I opened a can with it here.
Some of the Maxamet Manix 2 LW folders tested to 67rc as well with Kurt's testing.
Personally I stopped following the material data sheet recommendations for heat treatment protocols for these types of steels. They seem to focus on making wear resistant parts rather than high strength and stable edge cutting knives.
The Stability focused HT does great on 15v but we also see that doesn't make it invincible. Keep in mind nothing I've ever found holds up to ridiculous abusive testing at 0.005" bte yet with actually using as a knife its simply breathe taking in use.
Yes it's interesting to see how everything works in concert between hardness and geometry in such an extreme steel. Should help put some details into context and connect the dots for some on how edge performance works and the trade offs involved. It's a vast and difficult subject to get into I find.
There are so many layers to the equation. At first blush (to me) it might seem like higher hardness would lead to less edge stability. That's actually amazing that such a high carbide steel at that hardness with incredibly thin edge geometry can take that kind of hard use and not suffer serious damage.
Now I'm curious how Maxamet would fare in an apples-to-apples comparison. It's got similar carbide volume to CPM 15V (perhaps with more tungsten and less vanadium carbide.) Spyderco's heat treat with Maxamet is geared toward high hardness - up to 69 HRC - so shouldn't it have similar edge strength to CPM 15V?
Oh and how about CPM REX 121? :D
BBB I know I've said this before but thanks for your contributions to knife geekdom. Between you and Larrin Thomas I am learning more than I ever could've imagined about knife metallurgy. You guys are the best! :cool:
The Maxamet Manix 2 I had was more than twice as thick behind the edge than this CPM 15V knife at 0.022" bte and still not as stable even though very strong.
I opened a can with it here.
Some of the Maxamet Manix 2 LW folders tested to 67rc as well with Kurt's testing.
Personally I stopped following the material data sheet recommendations for heat treatment protocols for these types of steels. They seem to focus on making wear resistant parts rather than high strength and stable edge cutting knives.
The Stability focused HT does great on 15v but we also see that doesn't make it invincible. Keep in mind nothing I've ever found holds up to ridiculous abusive testing at 0.005" bte yet with actually using as a knife its simply breathe taking in use.
Yeah I saw that video back when I was thinking about buying a Maxamet Native. Do you think that your custom heat treat protocol will be able to get Maxamet close to CPM 15V levels of edge stability, or are the compositions too dissimilar?
I've never even used a knife that was 0.005" bte; I still consider 0.010" bte to be super thin edge geometry. And a knife steel that can take that thin edge geometry and still cut open cans with minimal damage, seems like a perfect balance of performance and strength.
Yes it's interesting to see how everything works in concert between hardness and geometry in such an extreme steel. Should help put some details into context and connect the dots for some on how edge performance works and the trade offs involved. It's a vast and difficult subject to get into I find.
There are so many layers to the equation. At first blush (to me) it might seem like higher hardness would lead to less edge stability. That's actually amazing that such a high carbide steel at that hardness with incredibly thin edge geometry can take that kind of hard use and not suffer serious damage.
Now I'm curious how Maxamet would fare in an apples-to-apples comparison. It's got similar carbide volume to CPM 15V (perhaps with more tungsten and less vanadium carbide.) Spyderco's heat treat with Maxamet is geared toward high hardness - up to 69 HRC - so shouldn't it have similar edge strength to CPM 15V?
Oh and how about CPM REX 121? :D
BBB I know I've said this before but thanks for your contributions to knife geekdom. Between you and Larrin Thomas I am learning more than I ever could've imagined about knife metallurgy. You guys are the best! :cool:
The Maxamet Manix 2 I had was more than twice as thick behind the edge than this CPM 15V knife at 0.022" bte and still not as stable even though very strong.
I opened a can with it here.
Some of the Maxamet Manix 2 LW folders tested to 67rc as well with Kurt's testing.
Personally I stopped following the material data sheet recommendations for heat treatment protocols for these types of steels. They seem to focus on making wear resistant parts rather than high strength and stable edge cutting knives.
The Stability focused HT does great on 15v but we also see that doesn't make it invincible. Keep in mind nothing I've ever found holds up to ridiculous abusive testing at 0.005" bte yet with actually using as a knife its simply breathe taking in use.
Yeah I saw that video back when I was thinking about buying a Maxamet Native. Do you think that your custom heat treat protocol will be able to get Maxamet close to CPM 15V levels of edge stability, or are the compositions too dissimilar?
I've never even used a knife that was 0.005" bte; I still consider 0.010" bte to be super thin edge geometry. And a knife steel that can take that thin edge geometry and still cut open cans with minimal damage, seems like a perfect balance of performance and strength.
If you watch that potato cutting video with a Keen eye you can hear and see that at 0.005" it's almost literally "falling through" the potato like nothing. Really makes me happy. 0.010" doesn't quite do that.
I have heat treatmented Maxamet also with a modified protocol. I personally just do not currently have the belts to process it. The six belts I just bought are dead now from grinding 15v so I'll have to sell a knife to get more belts to grind the Maxamet and see how it turned out.
