3V heat treat question

T

Tkrocky

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Sep 6, 2013
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So I'm sure this has come up a ton, but I was hoping some of you guys could lend some fresh insight into my heat treat process for 3V. Right now I am preheating to 1500 at which time I put the blade in, then I ramp up to 1980, hold for 30 minutes, then plate quench in 8 x 12 x 1" aluminum plates, and into LN overnight. I then tempered twice for 2 hours each at 400 degrees. I was aiming for 61 RC, and got 59. Any suggestions? Also, can i re heat treat it to get to the desired hardness?
 
I'm new to working with 3v, but thus far I have been tempering at 380, to hit 60+ RC. I have read of people tempering at as low as 360 or so. I'm actually not sure what the exact hardness numbers are, at varying temper temps, since the data sheets don't usually include cryo. But for sure, the lower you temper at, the higher your hardness will be (not that hardness is all that matters!)

It could also have something to do with your quench not being fast enough? I've been quenching in oil, and have never used plates, so I'm no expert. But I have read about people cooling their plates first, and/or blowing compressed air through them.

As far as re-heat treating, you can anneal it, and then start over. Off the Crucible data sheet:

Annealing
Heat to 1650°F (900°C), hold 2 hours, slow cool no faster than 25°F (15°C) per hour to 1100°F (595°C), then furnace cool or cool in still air to room temperature.
 
Mobius1 said:
I'm new to working with 3v, but thus far I have been tempering at 380, to hit 60+ RC. I have read of people tempering at as low as 360 or so. I'm actually not sure what the exact hardness numbers are, at varying temper temps, since the data sheets don't usually include cryo. But for sure, the lower you temper at, the higher your hardness will be (not that hardness is all that matters!)

It could also have something to do with your quench not being fast enough? I've been quenching in oil, and have never used plates, so I'm no expert. But I have read about people cooling their plates first, and/or blowing compressed air through them.

As far as re-heat treating, you can anneal it, and then start over. Off the Crucible data sheet:

Annealing
Heat to 1650°F (900°C), hold 2 hours, slow cool no faster than 25°F (15°C) per hour to 1100°F (595°C), then furnace cool or cool in still air to room temperature.
Click to expand...

Thanks for the response! Dude that is a long dang time in the oven! I don't know if that is worth it. It would probably cost more than just getting more steel haha. I think the lower temper is key. I did my next two at the lower temp and hit 61 so I think That was key!
 
Yeah, that's like a whole day to anneal! And a lot of programming!

But it makes sense, really. Brewing your coffee, is a lot easier than unbrewing it! The same goes with steel.
 
Mobius1 said:
Yeah, that's like a whole day to anneal! And a lot of programming!

But it makes sense, really. Brewing your coffee, is a lot easier than unbrewing it! The same goes with steel.
Click to expand...

Yeah that's true, I am going to see how much it costs and post it here. At least it is salvageable I guess!
 
Unless there is something about 3V that I am not aware of, I see no need to re-anneal the steel to re-do the HT. Just do it as before with any adjustments in the parameters.

Raising the austenitization to 2000-2010°F and using cryo after a snap temper may raise the hardness 2-3 points.
 
There are issues with prequenching materials like 3V, D2, M2 that can dictate an anneal due to extreme grain growth on a second austenitization because the carbides that pin the grains can dissolve on a second heat before hitting equilibrium. This is always a danger.

That said, in my experience with 3V, given the temps you're using you will be fine with a second heat without annealing. Be aware the carbon is already largely in solution so there is no need for a long second soak. Get it to temp, wait 10 minutes and quench.

For this I wouldn't preheat the work, charge directly into an oven already at full temp.

I believe that 3V should be tempered at 400 minimum. If you can't get the hardness you want with a 400-500 temper something else in your process is wrong and you will have the mushy chippy edge 3V can get when done badly.
 
I was trying to find where I had read about lower than 400°F temper on 3v, and realized it was Roman Landes' recipe. His recipe calls for austenizing at 1940-1958°F, and tempering at 356-392°F. Why is it that he recommends a lower temperature (Granted, 392 is pretty close to 400, but not 356!)? Is it because he quenches in oil?

But after reading your post, you have dropped my confidence in how good my heat treat is!! But now that I know I don't have to anneal it, I guess that means it's far easier for me to do some comparisons.

The hardest part for me, when I heat treat, is always wondering in the back of my mind, that my "good" heat treat, is actually not nearly the potential I could be reaching!
 
Nathan the Machinist said:
There are issues with prequenching materials like 3V, D2, M2 that can dictate an anneal due to extreme grain growth on a second austenitization because the carbides that pin the grains can dissolve on a second heat before hitting equilibrium. This is always a danger.

That said, in my experience with 3V, given the temps you're using you will be fine with a second heat without annealing. Be aware the carbon is already largely in solution so there is no need for a long second soak. Get it to temp, wait 10 minutes and quench.

For this I wouldn't preheat the work, charge directly into an oven already at full temp.

I believe that 3V should be tempered at 400 minimum. If you can't get the hardness you want with a 400-500 temper something else in your process is wrong and you will have the mushy chippy edge 3V can get when done badly.
Click to expand...

My 3V HT is preheat at 1475F before ramp up to 1975F but your method sound interesting about no preheat for lesser risk of grain growth.

Would you mind if I would like to know your austenitizing temp?
 
Nathan the Machinist said:
There are issues with prequenching materials like 3V, D2, M2 that can dictate an anneal due to extreme grain growth on a second austenitization because the carbides that pin the grains can dissolve on a second heat before hitting equilibrium. This is always a danger.

That said, in my experience with 3V, given the temps you're using you will be fine with a second heat without annealing. Be aware the carbon is already largely in solution so there is no need for a long second soak. Get it to temp, wait 10 minutes and quench.

For this I wouldn't preheat the work, charge directly into an oven already at full temp.

I believe that 3V should be tempered at 400 minimum. If you can't get the hardness you want with a 400-500 temper something else in your process is wrong and you will have the mushy chippy edge 3V can get when done badly.
Click to expand...

So I won't preheat for the the reheat treat, but when heat treating normal, annealed 3v, do you still use a pre heat?
 
shqxk said:
My 3V HT is preheat at 1475F before ramp up to 1975F but your method sound interesting about no preheat for lesser risk of grain growth.
Click to expand...

Generally speaking preheat has no effect on grain. It's to reduce distortion and make more even soak times in different sections. In your case you're austenitizing martensitic material and just need to get directly back to solution without fooling around.

Preheat is not a bad policy in general, but is largely pointless in cutlery and I think positives don't outweigh the negatives with the ovens most makers are using in their shops. These ovens have issues with exposed coils inches from the work and slow uneven ramps, it's best to simply avoid the issues and go in hot.
 
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