Heat treat question for a newb

[rodriguez7]

This might be kind of a dumb question, but since all I have to heat treat is my half ass back yard forge, with no actual heat control. From what I can tell, I put a diesel pyrometer, and seem to be reaching right at 1500 degrees. So I've been heat treating 15n20, and 80crv2 and have made a few test blades. With my lack of control, will I be able to get any benefit at all with a sub zero quench? I understand what it does with retained austenite. But could I possibly get a couple rc points higher, with some finer carbides? My 80crv2 doesn't seem to be as hard as it should after it's tempered, or maybe I'm tempering it to high, 425 x 2. But will sub zero possibly help fix my lack of control in any way? I guess I could experiment and find out for myself. But I figured I would ask any way.

 

[samuraistuart]

The sub zero isn't going to change carbide size at all. It doesn't touch carbide structure, just converts retained austenite to untempered martensite. There is no way to answer this question for you, as we cannot know if you are able to hold your blade at the recommended temp, or if you're overheating it. You probably ARE overheating, to some degree, but no way for us to know that.

 

[Busto]

Simple Carbon Steels do not respond to sub zero or cryogenic treatment. If you are certain that your steel soaked long enough without over heating and creating unwanted grain growth the Oil Quench is about as good as you get. You should probably drop the tempering down to 350-375 to improve your hardness RC. Do you have a way of testing hardness or are you just skating a file?

 

[rodriguez7]

I have no accurate way of measuring my soak times. And yes, I'm just checking it with a file. It skates after quench, so I'm guessing I'll just try dropping my temper temp and see what happens. I'll heat to magnetic, and soak for 3-5 minutes , then quench, I'm profiling some test blades this week, and have some parks 50 that will be in tomorrow.

 

[JTknives]

You can send me some heat treated coupons and I will check the hardness for you.

 

[rodriguez7]

That would probably work, so at least I have an idea. Can you pm me your shipping address? And by coupons, are you just using any piece, such as a square piece left over, and heat treating that? Removing all the scale? Thanks

 

[JTknives]

Yeah just a small extra chunk. Do the heat treat on it/them just like you would on your knives. Needs to be flat and ground, I can grind it here if you cant get it nice and flat. just click on the heat treat order sheet below in my signature, it has my address.

 

[rodriguez7]

Ok, thanks for your help. I'll let you know when I can get it done. I get my parks tomorrow, so I may try a couple.