A question about 3V austenitizing temperature and retained austenite.

HPD

HPD

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When using a low tempering protocol, what is the highest austenitizing temperature I should use with a dry ice slurry in order to ensure a low enough level of retained austenite for fine edge stability? 1975? 2000? 2025?
 
The rule of thumb is you want to make sure you don’t austenitize above the peak hardness. You can test it on your own by heat treating a range of coupons from different austenitizing temperatures. Test as-quenched and with a low temperature temper like 300F. You can also decide to add in a “factor of safety“ below the absolute peak.
 
Larrin said:
The rule of thumb is you want to make sure you don’t austenitize above the peak hardness. You can test it on your own by heat treating a range of coupons from different austenitizing temperatures. Test as-quenched and with a low temperature temper like 300F. You can also decide to add in a “factor of safety“ below the absolute peak.
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Unfortunately, I don't own a hardness tester. I suppose I could find a local shop to test the coupons for me. If I had a hardness tester I would go hog wild, lol. Thanks for your reply.
 
Lorien said:
I'm sure I'm not the only one who gets a little shiver up their spine when they see that Larrin's answered a heat treating question here ;)
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He gave a pretty straightforward answer on what you need to do to get the information. Now I'm pretty sure I won't get many BS answers, lol. In lieu of doing those tests I'll probably just have to be conservative with my HT until I decide to bite the bullet.
 
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You could always go the currently non popular BF option of following the recommended data sheet heat treat which recomends a 1000°F temper temperature that would eliminate most if not all of the RA.

Yes you loose a little fine edge stability and some corrosion resistance but there are countless thousands of 3v knives out there with the high temper heat treatment and people are loving them.
 
HPD said:
Unfortunately, I don't own a hardness tester. I suppose I could find a local shop to test the coupons for me. If I had a hardness tester I would go hog wild, lol. Thanks for your reply.
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I can run them on my tester if you want to send them my way. I usually run my 3V 63 hrc 2050 and then a 400 temper if my notes are right. It’s likely I’ve used a 350 temper before.
 
Seedy Lot said:
You could always go the currently non popular BF option of following the recommended data sheet heat treat which recomends a 1000°F temper temperature that would eliminate most if not all of the RA.

Yes you loose a little fine edge stability and some corrosion resistance but there are countless thousands of 3v knives out there with the high temper heat treatment and people are loving them.
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I'll stick with 1975F and low tempering unless someone can convince me that going higher will give me better edge stability when using dry ice. I've done two 3V blades, one at 1950 and the other at 1975, and they both seem to be fine. I'm making a smaller thin blade and don't need a crazy amount of impact toughness, but something a little harder with decent toughness appeals to me. I know some might say to just use Magnacut, but 3V is a little easier to finish and has enough stain resistance with the low temper.
 
Thescrawnylumberjack said:
I can run them on my tester if you want to send them my way. I usually run my 3V 63 hrc 2050 and then a 400 temper if my notes are right. It’s likely I’ve used a 350 temper before.
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I'll consider that. Thanks for the offer.
 
HPD said:
I'll stick with 1975F and low tempering unless someone can convince me that going higher will give me better edge stability when using dry ice. I've done two 3V blades, one at 1950 and the other at 1975, and they both seem to be fine. I'm making a smaller thin blade and don't need a crazy amount of impact toughness, but something a little harder with decent toughness appeals to me. I know some might say to just use Magnacut, but 3V is a little easier to finish and has enough stain resistance with the low temper.
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I woukd contend if you want harder then there are plenty of other steels that easily get very hard. 4v for example has always been hard for me to get tempered down to 62. Cruwear will also easily be pushed to higher hardness then usually seen with 3v.
 
I think biggest take away right now is you need to be able to test your hardness and make descions according to the results you are seeking from your own heat treat.
 
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Seedy Lot said:
I think biggest take away right now is you need to be able to test your hardness and make descions according to the results you are seeking from your own heat treat.
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Yeah, I agree with that. What does everyone think of this tester? Waste of money or worth considering?
PHR-1-Portable-Rockwell-Hardness-Tester (link removed)
Please - no sales links!
 
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HPD said:
When using a low tempering protocol, what is the highest austenitizing temperature I should use with a dry ice slurry in order to ensure a low enough level of retained austenite for fine edge stability? 1975? 2000? 2025?
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Roman Landes Heat Treatment recomendation

“Now this is what I would recommend for heat treat cpm 3v:



1st preheat: 500-600°C, equalize

2nd preheat:800-900°C, equalize

Autenize: 1060-1070°C, equalize, soak 30-35min

Quench in Oil preheated 60-80°C

Cryo: immediately after cleaning, minimum -80°C or lower soak 30min

1st Temper: 150°C equalize, soak 2hrs, quench in water

Cryo: immediately after temper

2nd Temper: 180-200°C equalize, soak 2hrs

should give you 60+ and a fine durable grain.



RGDS Roman”

Roman Landes
 
There’s no grain refinement steps above and grain refinement is a slow process on high alloy steels. So the grain will be fine regardless of the preheat steps.

I don’t think you need to preheat and equalize on knives. I know some will argue that their famous knife maker uncle has always done it that way and he’s never had a dull edge in his 150 years of knife making. Knives are small pieces of steel that heat through pretty fast and those equalizing steps are for large parts or possibly large industrial batches. If you do it great but it’s most likely not necessary.

Also the second cryo will do next to nothing.

I agree with getting that blade into cryo as fast as you can. You can certainly do oil or plate quench.

I agree with tempering at 300 then increasing the temperature to achieve the desired hardness which is easy to do when you have a hardness tester. Without it you’re just kinda guessing and hoping for the best.
 
Thescrawnylumberjack said:
There’s no grain refinement steps above and grain refinement is a slow process on high alloy steels. So the grain will be fine regardless of the preheat steps.

I don’t think you need to preheat and equalize on knives. I know some will argue that their famous knife maker uncle has always done it that way and he’s never had a dull edge in his 150 years of knife making. Knives are small pieces of steel that heat through pretty fast and those equalizing steps are for large parts or possibly large industrial batches. If you do it great but it’s most likely not necessary.

Also the second cryo will do next to nothing.

I agree with getting that blade into cryo as fast as you can. You can certainly do oil or plate quench.

I agree with tempering at 300 then increasing the temperature to achieve the desired hardness which is easy to do when you have a hardness tester. Without it you’re just kinda guessing and hoping for the best.
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“My guys” are like me, obsessed with high performance. Toughness, in my case. They “run the extra mile” for that 5-10% gain in performance.
 
Thescrawnylumberjack said:
If

Then why not use CPM 1V/ztuff/CD1 if you’re going for high performance toughness?
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I don’t use 3v, never did and most probably never will. But the OP was asking about austenization temperatures regarding 3v, and I remembered Roman Landes recommendation about how to heat treat it. This doesn’t mean he uses it or even that he likes it! He probably thought: if there’s so interest on this steel, here’s the ht receipt that I recommend.
 
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