Ankerson
Knife and Computer Geek
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- Nov 2, 2002
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- 21,093
Yeah I know, that's why I don't use it.
I would be cutting forever..... And using a lot more testing material.
Manila is very hard on the edges.
LionSteel Steels
- Thread starter RamZar
- Start date
Yeah I know, that's why I don't use it.
I would be cutting forever..... And using a lot more testing material.
Manila is very hard on the edges.
molletta
Gold Member
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- Sep 1, 2004
- Messages
- 1,582
Test in not do un the curved blade near point but only in straight blade part. There is not difference in two sleipner. On large blade there is more streight edge to drag.
RamZar
Gold Member
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So, one is a push cut (660 cuts) and the other a drag cut (1700+ cuts)?
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- Jan 25, 2010
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- 463
Thanks for all the info and back and forth.
Im glad I'm not alone in thinking Sleipner seems to out perform it's alloy content.
I really like all the info about all the different testing you guys do.
Im glad I'm not alone in thinking Sleipner seems to out perform it's alloy content.
I really like all the info about all the different testing you guys do.
I'm currently field testing the M7 satin non chemically blackened version and after a brief immersion in freshwater the blade shows corrosive pitting. With less Cr than D2 the Sleipner will def rust up but i would not have expected corrosive pitting (BTW it's not uniform over the blade) Uddeholm praise this "Modern version of D2" but my comparisons to D2 show for knives (not cutting tools for machining and milling) there is little difference in edge performance for similar edge angles.
I would shed my contribute in spirit of cooperation, that Gianni has already experienced, basing on Professor Emeritus Verhoeven and Dr. Landes publications, not to mention many other in depth publications that I already sent to Gianni on 8/8/2014 via email.
All of this material has been sent years ago to Elliot Williamson and Neels Roos as well .
The former used the HT data per my specs to realize not only three folders + 1fixed blade in M390 but also a kitchen knife in Elmax for me, but the guidelines had been used from then on also for other highly alloyed steels, notably S90V.
Neels Roos defined all of this literature ("Now, what a read..."), which for me it is a pride and honour.
These literature involved Elmax and M390.
I had request on Britishblades of disclosing the HT privately to some EU customakers, which I did gladly. Mark Hill of UK, and some others from Poland.
With this being said, and limiting to M390 (as the story for Elmax would be pretty much the same) I would signal to you my posts in this thread
http://www.bladeforums.com/forums/s...n-Edge-Retention-cutting-5-8-quot-rope/page47
Here I made some strictly metallurgical remarks that I don't feel like duplicating here (exception made for SH) and notably I put the link to BU m390 datasheet from which you can get clearly the message that M390 delivers its best when oil quenched.
But I acknowledge that this NOT a viable solution for production blades, so we should limit to vacuum HT.
PART 1
A publication from BU "CARBIDE DISSOLUTION RATE AND CARBIDE CONTENTS IN USUAL HIGH ALLOYED TOOL STEELS AT AUSTENITIZING TEMPERATURES BETWEEN 900 ◦CAND 1250 ◦C" S. Wilmes and G. Kientopf, Uddeholm GmbH, Düsseldorf, Deutchland is quite interesting to get an idea, among other steels, of M390 behaviour.
In as annealed state it has the follwing carbide composition:
Amount of Undissolved Carbides =>28.6%; 91 % Cr23C6; 9 % V4C3 (percentage expressed in weight);
In the as quenched at 1200°C we have 17,6% undissolved carbides Cr7C3; V4C3 (small amount)(percentage expressed in weight);
So we've already two results.
1)39.5% less undissolved carbides, which will help us having more available C and Cr in solid solution for hardness and stain resistance. Make a bookmark to the latter, as later it will help us (Secondary Hardening).
2)Weaker Cr23C6 carbides are gone (that's why we have more C and Cr in solid solution) and we've only K2 Cr carbides (the hardest of Cr carbides) and MC V carbides (even harder).
Not only Cr23C6 carbides are the weakest of Cr ones, not only they bind a hell of C and Cr, but they are also responsible of Intergranular Corrosion.
Lets explain what it is (Verhoeven, Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel pages 137-139).
"When a small particle of K1 (Cr23C6) forms in a matrix of either ferrite or austenite, the Cr atoms in the carbide are subtracted from the matrix iron immediately surrounding the particle. If this causes the %Cr to drop much below 12 %Cr in the surrounding matrix the steels become susceptible to corrosion and are said to be "sensitized". Since the carbides prefer to form along the grain boundaries of the matrix the corrosion occurs along the grain boundaries and this type of corrosion is therefore called intergranular corrosion. Hence, sensitization is said to occur when a low temperature heat treatment, such as tempering, causes K1 precipitate particle formation to the extent that intergranular corrosion may occur"
He then mentions 440C to make a practical example pinpointing the fact that at 1100°C and upon quenching we will have Martensite + K2 (Cr7C3) carbides.
What 440C achieves theoretically at 1100°C M390 achieves at 1200°C (15' for a knife blade). To be picky it would be 1180°C when NOT using a vacuum furnace.
PART 2
QUENCHING
When Vacuum HT is used, Positive Gas Pressure must be used also as far as quenching is concerned: BU says minimum 3.5Bar. I would hotly recommend 5Bar.
CCT graph available in Elmax own datasheet could be used to have a very good quenching timing for M390 as well, taking into consideration the higher Aust temperature.
I.e.: roughly 300°C per minute (4mm specimen) until 550°C then room temperature cooling until 70°C. Followed immediately by tempers.
Now, it is true that M390 is austenitized at 1200°C (against 1100°C of Elmax) but it has 0.6% of Tungsten which:
1)Decrease the critical quenching rate to avoid Bainite nose, or if you prefer shifts the bainite nose to the right of CCT graph.
2)Gifts its contribute to "Particle Drag" (Prof. Verhoeven, ibidem), thus limiting furtherly grain growth together with V and Moly in this steel.
So 230°C per minute until 550°C and then room temperature until 70°C.
PART 3
TO CRYO OR NOT TO CRYO?
My quick answer is negative.
Lets elaborate: M390 has the advantage of having a very very rewarding secondary hardness range. Cryo will solve only the ratained austenite problem.
SH will solve RA and possible Fe3C (Cementite, very hard but brittle) problem all in a row.
PART 4
TEMPERING
I've anticipated that SH on M390 solves two problems. RA and residuals of Fe3C (AKA Cementite). This is possibly why also S90V/comparable grade PM steels perform very well after SH: i.e. greatly reduced microchipping, as Elliot Williamson has remarked.
It is true that some Cr will be tied up in secondary Cr carbides, but V and W which are stronger carbide formers will limit this.
"Secondary hardening is caused by the formation of clusters of atoms of alloying elements and carbon (a maximum hardness often corresponds to the clusters) and the replacement of
relatively coarse particles of cementite by much more disperse precipitates of special carbides (TiC, VC, Mo2C, W2C). When these particles coagulate, hardness decreases.
The chromium additive causes a small secondary hardening. This is connected with a rapid coagulation of the Cr7C3 carbide at 550C (10208F) as opposed to Mo2C and especially W2C. During secondary hardening an increase in the yield stress is accompanied by an increase in toughness owing to dissolution of coarse cementite particles..........Secondary hardening is a result of the transformation of RA to martensite on cooling from the tempering temperature, and of precipitation of an ultrafine dispersion of alloy carbides.
Tungsten, vanadium , chromium, and molybdenum that are the strong carbide-forming elements are most commonly used to achieve secondary hardening.
To take advantage of their precipitation characteristics, they must be dissolved in austenite during the austenitizing treatment in order to be incorporated into the martensite formed during quenching with sufficient supersaturation for secondary hardening during tempering."
Source: Engineering - Steel Heat Treatment Handbook - Metallurgy And Technologies, 2Nd Edition - (George E Totten) Taylor & Francis Crc Press 2007
I know two possible remarks:
1)Decreased stain resistance.
2)Decreased toughness.
I will not hide. Both are true.
From my sources I have evidence of differences in corrosion resistance in Solution A 5% HNO3 -1% HCl / 3 hours / room temperature
Solution B 10%CH3COOH / 24 hours / boiling environments. Let me know, please, if you cut in such environments for such long times.
Normal stain resistance it is quite less demanding and I've never had an M390 blade (all SHd) staining either during my Alps or my Tuscany trekkings.
Toughness wise, when M390 is Austen. at 1150°C ant SH at 540°C it has ca 35J of toughness against 43J it would have had if tempered at 250°C.
Source: PMPLASTICMOULDSTEELSWEAR RESISTANT AND CORROSION RESISTANT MARTENSITIC CHROMIUM STEELS
C. Kerschenbauer,M.O. Speidel,Institute of Metallurgy,ETH Zuerich,Switzerland,G. Lichtenegger, J. Sammer and K. Sammt,Boehler Edelstahl Kapfenberg, Austria
These are the conditions needed to HT M390, would you wish to ACTUALLY see what it delivers
All of this material has been sent years ago to Elliot Williamson and Neels Roos as well .
The former used the HT data per my specs to realize not only three folders + 1fixed blade in M390 but also a kitchen knife in Elmax for me, but the guidelines had been used from then on also for other highly alloyed steels, notably S90V.
Neels Roos defined all of this literature ("Now, what a read..."), which for me it is a pride and honour.
These literature involved Elmax and M390.
I had request on Britishblades of disclosing the HT privately to some EU customakers, which I did gladly. Mark Hill of UK, and some others from Poland.
With this being said, and limiting to M390 (as the story for Elmax would be pretty much the same) I would signal to you my posts in this thread
http://www.bladeforums.com/forums/s...n-Edge-Retention-cutting-5-8-quot-rope/page47
Here I made some strictly metallurgical remarks that I don't feel like duplicating here (exception made for SH) and notably I put the link to BU m390 datasheet from which you can get clearly the message that M390 delivers its best when oil quenched.
But I acknowledge that this NOT a viable solution for production blades, so we should limit to vacuum HT.
PART 1
A publication from BU "CARBIDE DISSOLUTION RATE AND CARBIDE CONTENTS IN USUAL HIGH ALLOYED TOOL STEELS AT AUSTENITIZING TEMPERATURES BETWEEN 900 ◦CAND 1250 ◦C" S. Wilmes and G. Kientopf, Uddeholm GmbH, Düsseldorf, Deutchland is quite interesting to get an idea, among other steels, of M390 behaviour.
In as annealed state it has the follwing carbide composition:
Amount of Undissolved Carbides =>28.6%; 91 % Cr23C6; 9 % V4C3 (percentage expressed in weight);
In the as quenched at 1200°C we have 17,6% undissolved carbides Cr7C3; V4C3 (small amount)(percentage expressed in weight);
So we've already two results.
1)39.5% less undissolved carbides, which will help us having more available C and Cr in solid solution for hardness and stain resistance. Make a bookmark to the latter, as later it will help us (Secondary Hardening).
2)Weaker Cr23C6 carbides are gone (that's why we have more C and Cr in solid solution) and we've only K2 Cr carbides (the hardest of Cr carbides) and MC V carbides (even harder).
Not only Cr23C6 carbides are the weakest of Cr ones, not only they bind a hell of C and Cr, but they are also responsible of Intergranular Corrosion.
Lets explain what it is (Verhoeven, Metallurgy of Steel for Bladesmiths & Others who Heat Treat and Forge Steel pages 137-139).
"When a small particle of K1 (Cr23C6) forms in a matrix of either ferrite or austenite, the Cr atoms in the carbide are subtracted from the matrix iron immediately surrounding the particle. If this causes the %Cr to drop much below 12 %Cr in the surrounding matrix the steels become susceptible to corrosion and are said to be "sensitized". Since the carbides prefer to form along the grain boundaries of the matrix the corrosion occurs along the grain boundaries and this type of corrosion is therefore called intergranular corrosion. Hence, sensitization is said to occur when a low temperature heat treatment, such as tempering, causes K1 precipitate particle formation to the extent that intergranular corrosion may occur"
He then mentions 440C to make a practical example pinpointing the fact that at 1100°C and upon quenching we will have Martensite + K2 (Cr7C3) carbides.
What 440C achieves theoretically at 1100°C M390 achieves at 1200°C (15' for a knife blade). To be picky it would be 1180°C when NOT using a vacuum furnace.
PART 2
QUENCHING
When Vacuum HT is used, Positive Gas Pressure must be used also as far as quenching is concerned: BU says minimum 3.5Bar. I would hotly recommend 5Bar.
CCT graph available in Elmax own datasheet could be used to have a very good quenching timing for M390 as well, taking into consideration the higher Aust temperature.
I.e.: roughly 300°C per minute (4mm specimen) until 550°C then room temperature cooling until 70°C. Followed immediately by tempers.
Now, it is true that M390 is austenitized at 1200°C (against 1100°C of Elmax) but it has 0.6% of Tungsten which:
1)Decrease the critical quenching rate to avoid Bainite nose, or if you prefer shifts the bainite nose to the right of CCT graph.
2)Gifts its contribute to "Particle Drag" (Prof. Verhoeven, ibidem), thus limiting furtherly grain growth together with V and Moly in this steel.
So 230°C per minute until 550°C and then room temperature until 70°C.
PART 3
TO CRYO OR NOT TO CRYO?
My quick answer is negative.
Lets elaborate: M390 has the advantage of having a very very rewarding secondary hardness range. Cryo will solve only the ratained austenite problem.
SH will solve RA and possible Fe3C (Cementite, very hard but brittle) problem all in a row.
PART 4
TEMPERING
I've anticipated that SH on M390 solves two problems. RA and residuals of Fe3C (AKA Cementite). This is possibly why also S90V/comparable grade PM steels perform very well after SH: i.e. greatly reduced microchipping, as Elliot Williamson has remarked.
It is true that some Cr will be tied up in secondary Cr carbides, but V and W which are stronger carbide formers will limit this.
"Secondary hardening is caused by the formation of clusters of atoms of alloying elements and carbon (a maximum hardness often corresponds to the clusters) and the replacement of
relatively coarse particles of cementite by much more disperse precipitates of special carbides (TiC, VC, Mo2C, W2C). When these particles coagulate, hardness decreases.
The chromium additive causes a small secondary hardening. This is connected with a rapid coagulation of the Cr7C3 carbide at 550C (10208F) as opposed to Mo2C and especially W2C. During secondary hardening an increase in the yield stress is accompanied by an increase in toughness owing to dissolution of coarse cementite particles..........Secondary hardening is a result of the transformation of RA to martensite on cooling from the tempering temperature, and of precipitation of an ultrafine dispersion of alloy carbides.
Tungsten, vanadium , chromium, and molybdenum that are the strong carbide-forming elements are most commonly used to achieve secondary hardening.
To take advantage of their precipitation characteristics, they must be dissolved in austenite during the austenitizing treatment in order to be incorporated into the martensite formed during quenching with sufficient supersaturation for secondary hardening during tempering."
Source: Engineering - Steel Heat Treatment Handbook - Metallurgy And Technologies, 2Nd Edition - (George E Totten) Taylor & Francis Crc Press 2007
I know two possible remarks:
1)Decreased stain resistance.
2)Decreased toughness.
I will not hide. Both are true.
From my sources I have evidence of differences in corrosion resistance in Solution A 5% HNO3 -1% HCl / 3 hours / room temperature
Solution B 10%CH3COOH / 24 hours / boiling environments. Let me know, please, if you cut in such environments for such long times.
Normal stain resistance it is quite less demanding and I've never had an M390 blade (all SHd) staining either during my Alps or my Tuscany trekkings.
Toughness wise, when M390 is Austen. at 1150°C ant SH at 540°C it has ca 35J of toughness against 43J it would have had if tempered at 250°C.
Source: PMPLASTICMOULDSTEELSWEAR RESISTANT AND CORROSION RESISTANT MARTENSITIC CHROMIUM STEELS
C. Kerschenbauer,M.O. Speidel,Institute of Metallurgy,ETH Zuerich,Switzerland,G. Lichtenegger, J. Sammer and K. Sammt,Boehler Edelstahl Kapfenberg, Austria
These are the conditions needed to HT M390, would you wish to ACTUALLY see what it delivers
- Joined
- Feb 23, 2009
- Messages
- 773
2015 Steel program:
We are going to introduce two new steel in LionSteel production.
- folding knife TRE, M390
- fixed blade (second part of 2015) K390
We are going to introduce two new steel in LionSteel production.
- folding knife TRE, M390
- fixed blade (second part of 2015) K390
Great Gianni :thumbup:
Now please please please, heat treat M390 (see just above) and K390 as they deserve
RamZar
Gold Member
- Joined
- Mar 3, 2013
- Messages
- 11,471
Very nice!
Love M390 in everything and I even have a fixed blade in it. Great corrosion resistance, edge retention, hardness and fairly easy to sharpen. I live a few miles from Pacific Ocean and combined with salt water, humidity, sweat, dust, etc. it's tough on steel with too much carbon and not enough chromium.
Any reason you picked Bohler K390 over Uddeholm Vanadis 4 Extra? I like them both.
I hope to see a rescue type knife from LionSteel in Bohler N680 where nitrogen replaces a lot of the carbon for unbelievable corrosion resistance.
molletta
Gold Member
- Joined
- Sep 1, 2004
- Messages
- 1,582
I chose K390 because can have high wear and streinght at lower hardness than m3:2, M4, V4e. For hardness over 63 toughness i usually less than 40J.
K390 at 60/61 have similar wear, toughness over 40. K390 have also better corrosion resistance.
Sorry only Italian at this moment.
http://www.mollettaknives.com/progetti/molletta-iago.html
K390 at 60/61 have similar wear, toughness over 40. K390 have also better corrosion resistance.
Sorry only Italian at this moment.
http://www.mollettaknives.com/progetti/molletta-iago.html
With given respect Mik, as far as M390 is concerned, what I published above is the result of roughly 5 years devoted to that steel and a bunch of info flow between myself and Elliot Williamson and Neels Roos and other respected (to say the least) custom makers.
The point is: we've got a very fine grained 3rd generation hypereutectoid very high alloyed steel.
Forgetting about secondary hardening+oil quenching, which no production maker will ever do, we are left with vacuum heat treat + 5 bar nitrogen overpressure + 2x low temperature tempering with deep cryo in between (to minimize retained austenite).
Talking about 20%Cr content the risk is having a great deal of M23C6 of Cr based carbides, which will cause fairly less Cr in solid solution AND intergranular corrosion issues.
To avoid this austenitizing temperature is to be pushed around 1170°C (safe limit enough for a production routine in order to avoid grain growth). Thus we will have M7C3 Cr carbides and MC Vanadium carbides and a HRC of 61-62+, which will ensure proper edge stability and adesive wear resistance.
I often read objections on the side of:
1)Lack of toughness
Such a HT will produce toughness in eccess of 40J (I already sent Gianni the research literature that mentions that)
2)Difficult sharpening on the field
This is the most ridiculous thing to hear.
I commonly use similarly HTd M390 blades everyday and they respond QUITE FAST to stropping with a Cr oxide charged leather, actually faster than a 58HRC N690 blade, which is no surprise at all.
Coming to K390, another very good steel, Bohler's own CCT diagram shows clearly that there is a wide region of A+K1 carbides (Austenite+V8C7 carbides) which are 7%. But there is also the chance of having some Cr7C3 carbides, which would be detrimental to corrosion resistance. This in the austenitized state. Quenching and tempering will eventually increase the chance of having Cr carbides.
I don't know what will be the meant using range of this blade, but hey it is 11cm long and 4mm thich, it will never be a chopper and at an 1110°C/500°C HT there would be plenty of toughness still. Bohler makes it statutory a 5bar Nitrogen overpressure for quenching, BTW.
Higher aust. temp would also favour more free Moly in solid solution (pitting resistance).
Grain growth.
Once again... 1%W will 1)Decrease the critical quenching rate to avoid Bainite nose, or if you prefer shifts the bainite nose to the right of CCT graph, even if avoiding Bainite is still demanding with this steel.
2)Gifts its contribute to "Particle Drag" (Prof. Verhoeven, ibidem), thus limiting furtherly grain growth together with V and Moly.
Cobalt (hot hardness will not be a mission critical parameter in a knife) will help raising the Ms temperature, nonetheless in Bohler datasheet the RA values are around 11%. I'd seriously consider deep cryo in between each of the three (at least 3 per Bohler) tempers.
So, in the end, if it will be less than 63-64HRC I will know what to expect, given that CPM-3V@60HRC has typically 5% Vanadium based MC carbides
You're welcome Mik, and please accept my thanks for having brought to us magnificent knives :thumbup:
RamZar
Gold Member
- Joined
- Mar 3, 2013
- Messages
- 11,471
Here's a link to translate that web page from Italian to English: https://translate.google.com/transl...ollettaknives.com/progetti/molletta-iago.html
The Molletta Iago fixed blade will be in K390 made by LionSteel. Is that the LionSteel M5?
- Blade length: 4.33 inches
- Blade thickness: 0.15748 inches
- Blade steel: Bohler K390 (HRC 60-61)
molletta
Gold Member
- Joined
- Sep 1, 2004
- Messages
- 1,582
Molletta Iago it's an experimental project, it will be made in a little number.
Later I think will put in the catalog Lionsteel. To decide if it will have the same characteristics of the experimental version or will be made with different materials.
The M5 is biggest than Iago in dimensions. It will be released directly as spring / Lionsteel.
There are still other projects ... One thing at a time. 3 (TRE) is coming.
Later I think will put in the catalog Lionsteel. To decide if it will have the same characteristics of the experimental version or will be made with different materials.
The M5 is biggest than Iago in dimensions. It will be released directly as spring / Lionsteel.
There are still other projects ... One thing at a time. 3 (TRE) is coming.
RamZar
Gold Member
- Joined
- Mar 3, 2013
- Messages
- 11,471
With given respect Mik, as far as M390 is concerned, what I published above is the result of roughly 5 years devoted to that steel and a bunch of info flow between myself and Elliot Williamson and Neels Roos and other respected (to say the least) custom makers.
The point is: we've got a very fine grained 3rd generation hypereutectoid very high alloyed steel.
Forgetting about secondary hardening+oil quenching, which no production maker will ever do, we are left with vacuum heat treat + 5 bar nitrogen overpressure + 2x low temperature tempering with deep cryo in between (to minimize retained austenite).
Talking about 20%Cr content the risk is having a great deal of M23C6 of Cr based carbides, which will cause fairly less Cr in solid solution AND intergranular corrosion issues.
To avoid this austenitizing temperature is to be pushed around 1170°C (safe limit enough for a production routine in order to avoid grain growth). Thus we will have M7C3 Cr carbides and MC Vanadium carbides and a HRC of 61-62+, which will ensure proper edge stability and adesive wear resistance.
I often read objections on the side of:
1)Lack of toughness
Such a HT will produce toughness in eccess of 40J (I already sent Gianni the research literature that mentions that)
2)Difficult sharpening on the field
This is the most ridiculous thing to hear.
I commonly use similarly HTd M390 blades everyday and they respond QUITE FAST to stropping with a Cr oxide charged leather, actually faster than a 58HRC N690 blade, which is no surprise at all.
Coming to K390, another very good steel, Bohler's own CCT diagram shows clearly that there is a wide region of A+K1 carbides (Austenite+V8C7 carbides) which are 7%. But there is also the chance of having some Cr7C3 carbides, which would be detrimental to corrosion resistance. This in the austenitized state. Quenching and tempering will eventually increase the chance of having Cr carbides.
I don't know what will be the meant using range of this blade, but hey it is 11cm long and 4mm thich, it will never be a chopper and at an 1110°C/500°C HT there would be plenty of toughness still. Bohler makes it statutory a 5bar Nitrogen overpressure for quenching, BTW.
Higher aust. temp would also favour more free Moly in solid solution (pitting resistance).
Grain growth.
Once again... 1%W will 1)Decrease the critical quenching rate to avoid Bainite nose, or if you prefer shifts the bainite nose to the right of CCT graph, even if avoiding Bainite is still demanding with this steel.
2)Gifts its contribute to "Particle Drag" (Prof. Verhoeven, ibidem), thus limiting furtherly grain growth together with V and Moly.
Cobalt (hot hardness will not be a mission critical parameter in a knife) will help raising the Ms temperature, nonetheless in Bohler datasheet the RA values are around 11%. I'd seriously consider deep cryo in between each of the three (at least 3 per Bohler) tempers.
So, in the end, if it will be less than 63-64HRC I will know what to expect, given that CPM-3V@60HRC has typically 5% Vanadium based MC carbides
Have you ever experiment about doing the cryogenic immediately after quench? From what I gather, the RA trend to stabilized after the first temper and cryo would hardly to convert them.
To avoid the precipitation of big chunks of Cr carbide at grain boundaries, I think you need to cooling down the steel as fast as possible from austenitizing temp to around your tempering range, equalize then let its cool slowly in still air.
Molten salt bath at 200°C might be your best bet for these.
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