HT Regimen for High Alloy Stainless Steels.

so bladsmth what you are saying is for cpm 154cm this heat treat is pretty much ideal? besides the temper degrees that is what i want to do :D

preheat to 1450 degrees F soak for 15 mins,
ramp to 1950 degrees F soak for 30 mins,
plate quench,
cryo over night,
temper at 500 degrees F for 2 hours,
water quench,
cryo for for 2 hours,
temper at 500 degrees F for 2 hours
air cool
 
bladsmth said:
Lloyd - Sorry, I was thinking about another maker, and confused the two of you.

Chad - The time between any step should be fairly short. Ra will stabilize if left alone for any period of time. The graph of your HT should look like a roller coaster, with no flat spots on it. Once the steel becomes austenized, it should be either heating or cooling, but not sitting still.
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sounds good so is a overnight cryo a bad idea then?
 
so is a overnight cryo a bad idea then?
Click to expand...

We have to be careful with definitions here.

Overnight subzero in dry ice is probably useless as the major change happening there is RA to martensite and propagates faster than the cold moves through the blade, so even a couple of minutes should be sufficient. Thoeretically.

Prolonged cryo in liquid nitrogen (e.g. overnight) has been shown to promote formation of carbides in a good way.
 
Tait is right.

A Sub-zero quench is done at -80F or lower (usually, dry ice at -105F). The transformation is hyper-sonic, so a few minutes is all that is needed.....15 minutes, to allow for complete temperature drop of the blade, should be more than enough.

If using liquid nitrogen to do Cryo treatment, a four to six hour soak will help form eta carbides.

On the second sub-zero treatment, all we are doing is transforming Ra, so a short time is all that is needed. 15 minutes is fine.

The time at Cryo will not stabilize the Ra, because it is at a temperature below the Mf. It is holding the Ra at temps above the Mf that stabilizes it.
 
I am going to try adding the sub zero after first temper step to my D2. Already do one after the plate quench. Thanks for the thoughts and explanations. Jim
 
Thanks for taking the time to write this one Stacy and to everyone who contributed with info based on their own experiences. I always enjoy reading threads like this.:thumbup:
 
I realize that 1080 and 1084 are not what we're talking about, but I'm curious if the quench from temper idea would still hold true? Say I temper a 1/8" thick blade of 1084 at 425f, then right out of the temper it goes into a water bath until cool, is that going to be any better than just letting it air cool from 425?

Regardless, thanks for the wealth of information and the time spent. It wasn't all new, but every time I learn a bit more and it sinks in a bit better.
 
It is generally more beneficial to cool from temper by quenching in water with most all steels. It will not crack the blade. If a crack that shows up after cooling the blade in water during temper, it was already there.

Just to make it clear:
The cooling from 425°F to room temperature by putting the blade in water is not the same as placing a 1450°F blade in water/brine.

When water quenching an austenite blade at 1450°F, it will convert into martensite at around 450°F. This conversion ,if done in water/brine , can be so rapid and create such stress on the blade edge that it tears the steel apart...AKA the dreaded PING.....and destroys the blade.

Once the blade has formed martensite in the initial quench, and the martensite has been tempered in the first temper period, the steel is not going to crack - because it isn't converting structures anymore.
 
Thanks, Stacy. I guess I'll add that to my routine. If nothing else it is easier than finding a spot to put a few hot blades in the kitchen where no one will accidentally touch them. :)
 
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