Recommendation? My first heat treating, what do the experts say

D

Dan512

Joined
Aug 19, 2019
Messages
28
So just made my first knives, it was supposed to be a batch of 4 small kitchen knifes. 2 didn’t make it (see below)

I made them out of 80CrV2 (or 1.2235 as we call it in Europe). Thickness at the spine is just under 3mm or around 3/64".

Hardened at 830°C / 1526°F in my electric oven and quenched in canola oil (45°C / 113° F)

2 blades came out all bent (I learnt since that I am not supposed to stir them around in the oil) and I broke them trying to straighten them out before the tempering, gotta learn the hard way.
punchself.gif


But at least this way I could put them under the kids cheapo USB microscope.

So here are the pics:

The 1st one is of a knife that I had to put through the oven 3 times before the file would slide over it, the final time I left it 10 minutes in the oven. So in all it will have spend approx 20 minutes at 830°C.



The 2nd and 3rd are from the second knife, it spent 6 minutes in the oven.





What do the experts think about the grain?
 
I am definitely not an expert, but the grain on the first one looks a bit coarse. The second looks alright though.

You have a lot of guts to try and straighten out of the quench! I would be too scared!!

Please post finished pics, I would love to see them done.
 
I agree above the 1st looks coarse while the 2nd looks good. You may have had a good HT the first time. You just might have had some decarb the first time you tested which is why the file bit in. Grind a small spot on the tang next time and check with the file.

I was in your position a couple years ago. My first broken knife was way coarser than what you showed above. I think it was JT who suggested making 5 small coupons and heat treating them at varying temperatures. Then test them (I was lucky enough to have a hardness tester) and break them to check the grain. Its a great learning experience. You could even make slightly longer pieces, sharpen them and see how they hold up. Then break them. After all, its ultimately edge retention and toughness that you're after.

That being said, it's hard to do as a new maker because you want to make a knife so bad. Not make and break coupons.
 
The grain of these pieces doesn't looks too good for me... Actually the first one is kinda bad.

You should try some thermal cycle to reduce the grain, like 20 minutes 800c air cool + 10 minutes 800c -> oil quench and 1 hour 680c for sub-critical annealing then perform the 6 minutes 830c-> quench.
 
Dan512 said:
I learnt since that I am not supposed to stir them around in the oil) and I broke them trying to straighten them out before the tempering
Click to expand...
Moving the blade while its in the oil is a good thing as long as you do it in a slicing motion not side to side. Also when the blade first comes out from the quench is a good time to straighten it, blade is very bendable for the first little bit out of the quench. after that you should straighten it during the temper
 
shqxk said:
The grain of these pieces doesn't looks too good for me... Actually the first one is kinda bad.

You should try some thermal cycle to reduce the grain, like 20 minutes 800c air cool + 10 minutes 800c -> oil quench and 1 hour 680c for sub-critical annealing then perform the 6 minutes 830c-> quench.
Click to expand...

I agree it's important to thermal cycle with descending heats to make sure you have fine grain. It's a necessity if forged, and even if strictly stock removal, it's a guarantee that your steel is in a good state prior to heat treating.
 
You must log in or register to reply here.
Back
Top