Tell Me your thoughts on CPM 15v

samuraistuart said:
I don't recall any steel company that provides their "factory recommended" HT and then another for "cutlery". There are a few companies that DO provide a cutlery HT, but their steels are specifically made for cutlery. Even then....we can change the recommended HT of cutlery steel to make it better.
Most of the PM steels are made for other applications, and the HT for such is tailored for that application. The knife industry really is small for these companies, so I can understand why they don't. But those of us who like to "dig in the dirt" about this stuff, we know how to tweak an "industrial" heat treatment for one that better suites our purposes.
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Which PM steel you use and how you test them to know that they a better then factory HT recipe ?
 
Natlek said:
bohler uddeholm claim that M390 is for knife to ? Why they don t give different HT recipe for that ?
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Start another thread about "heat treatment" this is for discussion about 15v. Besides, there is No winner in the argument cause there needs to be blades to back up the different ideas
to compare, so it's endless.
 
DeadboxHero said:
Start another thread about "heat treatment" this is for discussion about 15v. Besides, there is No winner in the argument cause there needs to be blades to back up the different ideas
to compare, so it's endless.
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Well , I think that you already got your answer :) But if you can HT that steel , go for it . And tell us how is to grind that half/carbide steel ;) And I will not borrow to you CBN belts :D
 
CPM alloys were designed primarily for the plastic injection industry, the factory recommended HT protocol is geared to that use.
Knife construction was never a consideration in the development of these alloys.
All other uses other than plastics injection nozzles is a secondary market.
 
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Natlek said:
Well , I think that you already got your answer :) But if you can HT that steel , go for it . And tell us how is to grind that half/carbide steel ;) And I will not borrow to you CBN belts :D
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Haha yeah those belts are pricey
 
Natlek, look up Nathan Carother's Delta 3V heat treatment. And about M390, it's original purpose was not for knives. Look at the Bohler website.
 
15v is just waaay too high in carbon for any knife application imho... unless you want to use 45 degree geometry and seriously look at 3 sessions of baking (tempering) after the quench (each of which will improve toughness usually)
 
I've got some on the way.
I'm going to send to Peters Heat treat.

I'm thinking 64-65 HRC

but it might be safer to go 62-63hrc

IDK we don't know until we know I suppose.

The stuff is so damn expensive it's best to just push the limits and see since its such a freakshow of a steel. No sense in playing it safe and trying to stuff a gorilla in a tuxedo.

It's still an 800lbs gorilla, let it be wild.
 
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One thing which seems consistent of all HT regimes I've read about, for all steels -> after quenching you get max hardness, but then each temper session afterwards adds great toughness for a tiny loss in hardness.

It's very much worth doing properly, in 15v's case - you want to do it at least twice or risk chipping & brittleness - according to the manufacturer:
https://www.crucible.com/eselector/prodbyapp/plastics/cpm15vp.html

and really, it sounds like a 3rd temper is in order, again, at a slightly lower temp
 
dirc said:
One thing which seems consistent of all HT regimes I've read about, for all steels -> after quenching you get max hardness, but then each temper session afterwards adds great toughness for a tiny loss in hardness.

It's very much worth doing properly, in 15v's case - you want to do it at least twice or risk chipping & brittleness - according to the manufacturer:
https://www.crucible.com/eselector/prodbyapp/plastics/cpm15vp.html

and really, it sounds like a 3rd temper is in order, again, at a slightly lower temp
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It's not as simple as getting softer with tempering. It depends on the aus temp. More alloy and carbide in solution in high alloy steels leads to more precipitation Harding. Hence why you see the high aus temp leading to higher hardness after tempering on the far right on the temp chart.

The game plan is to do the two preheats, then a 2150f aus temp and soak for 10 min and quench in medium speed oil to get below 1000f once down to room temp. Immediate cryo for 12 hours followed by a 1025 temper for 2 hours. Repeat twice.
Check RC and follow up from there.

The spec sheet says 64hrc but I'm hoping for a bump to 65hrc with the cryo. Also no snap temper. This steel looks like a retained austenite machine.

But I'd be happy at 64hrc.
If I wanted harder I'd just get rex121
 
DeadboxHero said:
But I'd be happy at 64hrc.
If I wanted harder I'd just get rex121
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Why you guys in USA a so obsessed with high HRC hardness ? You think you'll get useful knife from this steel in 64 Hrc ? I mind knife thin behind the edge .............to cut ? Or you will leave it thick as axe ? I have several knife in 67 Hrc..........they cut like laser , they stay sharp extremely long time .They a good for light task and soft medium....But I was limited , I did not have a choice ....You have are choice to / maybe / get good knife and you still push ??? Im almost 100% sure that on 64 hrc this 15V steel will chip on wind ...................
And leave a good finish before HT . I guarantee you that you'll regret that you started this ...... IF you try to put some fine finish with hand sanding on this steel :D
 
Natlek said:
Why you guys in USA a so obsessed with high HRC hardness ? You think you'll get useful knife from this steel in 64 Hrc ? I mind knife thin behind the edge .............to cut ? Or you will leave it thick as axe ? I have several knife in 67 Hrc..........they cut like laser , they stay sharp extremely long time .They a good for light task and soft medium....But I was limited , I did not have a choice ....You have are choice to / maybe / get good knife and you still push ??? Im almost 100% sure that on 64 hrc this 15V steel will chip on wind ...................
And leave a good finish before HT . I guarantee you that you'll regret that you started this ...... IF you try to put some fine finish with hand sanding on this steel :D
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Let's try and find out.
 
I think you'll be fine, Dead, now that I see how much thought you have put into the heat treat. The only problems I see would come from a sub-optimal heat treat.

I have a small, thin slicer in Rex 121 made by Bluntcut. The geometry is really, really thin. The steel is really, really hard (71 Rc and 0.007 edge shoulders and a spine 0.08 inches thick). Rex 121 doesn't have as much vanadium as 15V, but it has a mind-blowing amount of alloys: 3.5 percent C, 9.5 percent V, 10 percent tungsten and 9 percent cobalt. Altogether, alloys make up more than 41 percent of the blade, compared to just over 26 percent for 15V.

And yet that Rex 121 slicer doesn't chip, at least in normal use. It goes through cardboard like magic. It's scary.

Really look forward to seeing what you do with your 15V knives.
 
Twindog said:
I think you'll be fine, Dead, now that I see how much thought you have put into the heat treat. The only problems I see would come from a sub-optimal heat treat.

I have a small, thin slicer in Rex 121 made by Bluntcut. The geometry is really, really thin. The steel is really, really hard (71 Rc and 0.007 edge shoulders and a spine 0.08 inches thick). Rex 121 doesn't have as much vanadium as 15V, but it has a mind-blowing amount of alloys: 3.5 percent C, 9.5 percent V, 10 percent tungsten and 9 percent cobalt. Altogether, alloys make up more than 41 percent of the blade, compared to just over 26 percent for 15V.

And yet that Rex 121 slicer doesn't chip, at least in normal use. It goes through cardboard like magic. It's scary.

Really look forward to seeing what you do with your 15V knives.
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Thanks Josey

Man I really want a knife in Rex.

z8qqFk3.jpg

Can't wait to get this one done.
 
Shawn - you are having too much fun (except for burnt fingers from grinding)!

From my limited 15V slice & chop test data (iirc) - Peters' ht 65rc (blade from bodog) vs bcmw ht version 1.x at 70-71rc. Geez - hard to guess the outcome, since I write up this one :p ... Search for bodog's (banned now) posts on this.

With 15V high carbide (2+um dia) volume%, matrix spacing between carbides is narrow, so matrix plasticity is ineffectual. Have you notice - brittleness of annealed 15V, it has only extra 0.5%C worth of carbide compared to hardened 15V. Well, just chop with a sharpened annealed 15V edge, chop= chip. Rex121 has similar behavior as 15v, except 9%Co provide some extra elasticity especially in grain boundary = flex a little bit more.

When time permits (not for a while) - I like to try CPM T15 at ~67-69rc.

edit: btw - when your rex is ready for testing, for comparison I can send you a rex 71rc blade (no handle) to test (non-destruction, since I would like to have it around for testing).
 
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bluntcut said:
Shawn - you are having too much fun (except for burnt fingers from grinding)!

From my limited 15V slice & chop test data (iirc) - Peters' ht 65rc (blade from bodog) vs bcmw ht version 1.x at 70-71rc. Geez - hard to guess the outcome, since I write up this one :p ... Search for bodog's (banned now) posts on this.

With 15V high carbide (2+um dia) volume%, matrix spacing between carbides is narrow, so matrix plasticity is ineffectual. Have you notice - brittleness of annealed 15V, it has only extra 0.5%C worth of carbide compared to hardened 15V. Well, just chop with a sharpened annealed 15V edge, chop= chip. Rex121 has similar behavior as 15v, except 9%Co provide some extra elasticity especially in grain boundary = flex a little bit more.

When time permits (not for a while) - I like to try CPM T15 at ~67-69rc.

edit: btw - when your rex is ready for testing, for comparison I can send you a rex 71rc blade (no handle) to test (non-destruction, since I would like to have it around for testing).
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Wow crazy, got my brain churning with ideas.

I'd love to test your REX when I get mine running.
I plan on coming down this summer or fall. With some diamond stones, some steel to play with and a few beers, should be fun brother.
Shawn
 
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