Heat treat issues

Now knowing the source of your steel, it is quite possible that the issue you're having is the starting microstructure of the steel. Most of their carbon steels come very heavily annealed, which is great for machining, but not so great for heat treat response unless the blade has been forged already. If just doing stock removal, some of their steel requires a much higher than "standard" normalizing heat to break up the coarse carbide structure. A forged blade has already gone through high heats during the forging process. You will get a lot of opinions on different heat treat numbers, and that's fine, but this is what I would do if I KNEW the problem was not decarb, and I KNEW the steel was 80CrV2. I don't think your problem is the canola, warmed to 130°F I have had no issues with 80CrV2 back in the day prior to using Parks 50. 1/8" steel and thinner is what I normally use.

Normalize at a high heat, 1750°F (at least), 10 minute soak, let it air cool (break up the coarse carbide structure)
Thermal cycle twice at 1500°F, 10 minute soak each time, let it air cool (refine the aus grain a little bit)
Austenitize (harden) at 1525°F, 10 minute soak, quench in 130°F canola oil, or ambient/room temp/ Parks 50

I would highly recommend using some sort of antiscale compound like ATP-641 to radically reduce any decarb. But in the mean time make sure that's not the issue by grinding well into thte steel. Sounds like you are doing that, so that's good. 80CrV2 is a pretty forgiving steel for heat treating. But a lot of the carbon steels that come from the Buderus mill in Europe are very heavily spheroidized. It might be the issue.

Good luck!
 
Stuart Davenport Knives said:
Now knowing the source of your steel, it is quite possible that the issue you're having is the starting microstructure of the steel. Most of their carbon steels come very heavily annealed, which is great for machining, but not so great for heat treat response unless the blade has been forged already. If just doing stock removal, some of their steel requires a much higher than "standard" normalizing heat to break up the coarse carbide structure. A forged blade has already gone through high heats during the forging process. You will get a lot of opinions on different heat treat numbers, and that's fine, but this is what I would do if I KNEW the problem was not decarb, and I KNEW the steel was 80CrV2. I don't think your problem is the canola, warmed to 130°F I have had no issues with 80CrV2 back in the day prior to using Parks 50. 1/8" steel and thinner is what I normally use.

Normalize at a high heat, 1750°F (at least), 10 minute soak, let it air cool (break up the coarse carbide structure)
Thermal cycle twice at 1500°F, 10 minute soak each time, let it air cool (refine the aus grain a little bit)
Austenitize (harden) at 1525°F, 10 minute soak, quench in 130°F canola oil, or ambient/room temp/ Parks 50

I would highly recommend using some sort of antiscale compound like ATP-641 to radically reduce any decarb. But in the mean time make sure that's not the issue by grinding well into thte steel. Sounds like you are doing that, so that's good. 80CrV2 is a pretty forgiving steel for heat treating. But a lot of the carbon steels that come from the Buderus mill in Europe are very heavily spheroidized. It might be the issue.

Good luck!
Click to expand...
I will give that a try. Thank you. My primary metal is SUP9 but it’s from same supplier. NJSB says to treat it just like the 80crv2 they sell. I have atp on the way but it will be a week before it arrives. I use the 5/32 primarily with a few blades out of the 1/4”. Thanks again.
 
wingnutgabber said:
Thank you. I will look into treating differently do to this issue.
Click to expand...
If coarse spheroidizing was the issue with your NJSB 80CrV2, you would have already ruled that out with your 1650f normalizing for 18min which would have dissolved the coarse carbides.

You shouldn't mix and match protocols, the NJSB cycling is designed to work with a lower austenitizing temperature since after cycling it is a mix of pearlite and spheroidized carbides.

The KSN 1525f you used is designed for a fine spheroidized annealed structure. Not the pearlite mixed structure from the NJSB cycling.


Pearlite has faster kinetics meaning it dissolves carbon from the cementite significantly faster into solid solution than the spheroidized carbides hence why they recommend a lower austenitizing temperature in the NJSB heat treatment after NJSB cycling. The pearlite may have advantages for short soak times in a forge like Dr Larrin has shown in his testing but you don't need that.

The consequences of over-austenizing is too much carbon in solution which will reduce your hardness due to retained austenite.

Again, 1525f is over-austenitizing when using the NJSB cycling which will reduce hardness and edge stability.

The KSN 1525f is designed to work with fine spheroidizing which is created from the DET anneal step.

Remember, any heat treat cycling on simple high carbon steels that at the end skips a controlled slower cooling for annealing will have pearlite which is very easy to over-austenitize in a furnace especially higher heat and longer soaking.


I recommend getting an Instagram and taking up Devin on his offer. The IG is not only useful for communicating directly with other makers but also for showing your work and even selling it if that's your goal.

Lastly, if you use atp-641, just remember it has to be re-applied between thermal cycling, you might be better served skipping the thermal cycling all together since you are just stock removing or use stainless HT foil to protect from decarb until your austenitizing step.

Hence why your 1525f coupon was more successful.

The blades ran over an hour of heat treatment without atmosphere protection so the decarb was going to be legendary.

Meanwhile running just an austenitizing for 10-15min is not going to be as severe.

On shallow hardening steels I found the atp-641 further reduced hardenability. 80CrV2 won't have that problem but 1084 may.


Congrats on your new furnace.
 
Not necessarily. There was some W2 from that mill that required 1900°F if doing stock removal just to get it to harden to 65HRC+ post quench. Their 52100 way back in the day required 1750°F normalizing heat.
 
DevinT said:
I would get some O1 steel from a reputable supplier and see how it responds to your heat treatment rather than trying to get this steel to harden.

Hoss
Click to expand...
Unfortunately I won’t be able to do that. Dropped to much money on this steel already. Thanks though
 
DevinT said:
Unfortunately, you are on a long and frustrating path.

Keep doing the same thing and see if you get different results.

Hoss
Click to expand...
That’s life. I just need to figure out the correct way to heat treat SUP9-5155/5160. Will be changing up different things per all the different recommendations. My speed oil gets here Friday.
 
DeadboxHero said:
If coarse spheroidizing was the issue with your NJSB 80CrV2, you would have already ruled that out with your 1650f normalizing for 18min which would have dissolved the coarse carbides.

You shouldn't mix and match protocols, the NJSB cycling is designed to work with a lower austenitizing temperature since after cycling it is a mix of pearlite and spheroidized carbides.

The KSN 1525f you used is designed for a fine spheroidized annealed structure. Not the pearlite mixed structure from the NJSB cycling.


Pearlite has faster kinetics meaning it dissolves carbon from the cementite significantly faster into solid solution than the spheroidized carbides hence why they recommend a lower austenitizing temperature in the NJSB heat treatment after NJSB cycling. The pearlite may have advantages for short soak times in a forge like Dr Larrin has shown in his testing but you don't need that.

The consequences of over-austenizing is too much carbon in solution which will reduce your hardness due to retained austenite.

Again, 1525f is over-austenitizing when using the NJSB cycling which will reduce hardness and edge stability.

The KSN 1525f is designed to work with fine spheroidizing which is created from the DET anneal step.

Remember, any heat treat cycling on simple high carbon steels that at the end skips a controlled slower cooling for annealing will have pearlite which is very easy to over-austenitize in a furnace especially higher heat and longer soaking.


I recommend getting an Instagram and taking up Devin on his offer. The IG is not only useful for communicating directly with other makers but also for showing your work and even selling it if that's your goal.

Lastly, if you use atp-641, just remember it has to be re-applied between thermal cycling, you might be better served skipping the thermal cycling all together since you are just stock removing or use stainless HT foil to protect from decarb until your austenitizing step.

Hence why your 1525f coupon was more successful.

The blades ran over an hour of heat treatment without atmosphere protection so the decarb was going to be legendary.

Meanwhile running just an austenitizing for 10-15min is not going to be as severe.

On shallow hardening steels I found the atp-641 further reduced hardenability. 80CrV2 won't have that problem but 1084 may.


Congrats on your new furnace.
Click to expand...
I had to read your post a few times over a few days to where I think I understand what your saying. Basically I heated my metal to much and built up lots of carbon. As well as my mix and matching of heat treat is where my issues lie. I need to stick to one heat treat method by one company.

Also since i am doing stock removal, the cycling is not really needed? Just heat and quench?
The primary metal I am using is 5155 which is comparable to 5160.
 
wingnutgabber said:
I had to read your post a few times over a few days to where I think I understand what your saying. Basically I heated my metal to much and built up lots of carbon.
Click to expand...

Yes, for your 80CrV2 it is likely over austenitized
but only because of the microstructure you created during the thermal cycling before hardening not that 1525°F is universally too hot.

1525f is fine for the as received condition in both materials.

Also, keep in mind, the cycling reduced the hardenability and canola oil is very slow.

So, we have several things stacking combined with the hardcore decarb leading to an undesirable outcome.

wingnutgabber said:
As well as my mix and matching of heat treat is where my issues lie. I need to stick to one heat treat method by one company.
Click to expand...

Correct, they are not interchangeable and can lead to undesirable outcomes which isn't fun problem solving when you're just starting out.


wingnutgabber said:
Also since i am doing stock removal, the cycling is not really needed? Just heat and quench?
The primary metal I am using is 5155 which is comparable to 5160.
Click to expand...

Yes, keep it simple.

When you have more resources in the future, you can try both and compare in your knives with cut testing and destructive testing.

On a side note, 5160 is not going to get high hardness or as hard as 80CrV2.

Those materials are not interchangeable although they can have some overlap in uses, they will also work better or worse in different things.

So, it may be important to keep expectations within reality and also define the role of what you want the knife to do well.

Everything has trade-offs.


Lastly, hardness files and hardness scratch chisels don't have the best resolution and accuracy either so we can't get too obsessed about exact hardnesses using them.
 
DeadboxHero said:
Yes, for your 80CrV2 it is likely over austenitized
but only because of the microstructure you created during the thermal cycling before hardening not that 1525°F is universally too hot.

1525f is fine for the as received condition in both materials.

Also, keep in mind, the cycling reduced the hardenability and canola oil is very slow.

So, we have several things stacking combined with the hardcore decarb leading to an undesirable outcome.



Correct, they are not interchangeable and can lead to undesirable outcomes which isn't fun problem solving when you're just starting out.




Yes, keep it simple.

When you have more resources in the future, you can try both and compare in your knives with cut testing and destructive testing.

On a side note, 5160 is not going to get high hardness or as hard as 80CrV2.

Those materials are not interchangeable although they can have some overlap in uses, they will also work better or worse in different things.

So, it may be important to keep expectations within reality and also define the role of what you want the knife to do well.

Everything has trade-offs.


Lastly, hardness files and hardness scratch chisels don't have the best resolution and accuracy either so we can't get too obsessed about exact hardnesses using them.
Click to expand...
I will give your recommendations a shot.

The only reason I compared 80crv2 to 5155 is because when I asked NJSB for heat treat they told me to just do like 80crv2. They said they were comparable.
Thanks again
 
You must log in or register to reply here.
Back
Top