Liquid nitrogen

[mete]

How many of you cryo by putting the blade in the LN and how many suspend the blade above the LN ?

 

[Bruce Bump]

I slowly put them under the liquid, I hope thats the right answer?

 

[howiesatwork]

Just don't fish it out with your fingers!

 

[mete]

Just a survey, no right or wrong.

 

[Dan Gray]

I put Mine in slowly too.
then let it slosh all around on the way back home

haven't had one brake yet,
the last one I made I put in two very sharp stress points
( can't be seen while together)
in it to see if it becomes a problem or not, it didn't brake in the cryo and while soldering the guard in place,

as tight as the guard was it had to push on
those points hard that I created as the Brass swelled between them under the heat,,..
I think Stress points for non choppers are over rated
disclaimer: as I make them at least

 

[Arthur Washburn]

I submerger my blades in the LN.

 

[tmickley]

tied to stainless steel cable and soaked in the LN for 12 hours. It fizzles and smokes pretty good for a minute or two.

 

[H.L. Holbrook]

I dunk mine also.

 

[rhrocker]

I'm strickly carbon, so no reason to use LN, right? Or is there something (else) I don't know about?

 

[samf]

Robert i know on 52100 you can gain as much as 2RC using LN
It works great on carbon steels
Sam

 

[jhiggins]

I'm a dunker.

 

[Don Robinson]

I just bought an old dewar for LN on Ebay. Haven't got it yet, so I haven't seen the lid/cap arrangement.

Do you use a seperate container with a little LN in it to quench your blade, or do you take the cap off and put the blade in, then replace the cap?

I've always just used a styrofoam ice box with a tight fitting lid for LN or dry ice. Now I gots me a dewar. Or will have, if the guy ships it.

 

[rhrocker]

Robert i know on 52100 you can gain as much as 2RC using LN
It works great on carbon steels
Sam

That's interesting Sam. How, and when, is it used for carbon?

 

[Kevin R. Cashen]

52100 has so much carbon that it tends to stabilize austenite, so it can respond to LN, and if you are seeing gains in Rockwell this is very indicative of this. Of the alloys that you work with Robert, 1095 is the only one that comes close to this carbon level.

 

[rhrocker]

Mete, I didn't mean to hijack the post by getting on a tangent about dunking or not dunking carbon steel! However, from what I've just learned, looks like I'll be a dunker in short order. I need to arm twist the "time in the tank" for 52100 from you guys.

 

[mete]

Yes 52100 has enough stuff in it to have retained austenite. In it's frequent application in bearings care is taken to not have too much RA. Remember in any of these alloys excessive austenitizing temperature will increase the amount of RA. ....Cryo should never be used to make up for poor HT, do it right in the first place !!

 

[rhrocker]

Mete, so you're saying do a proper HT and forget the LN, or do a proper HT and include the LN as a bonus?

 

[navajas]

Hi Don, the Dewars have a cap designed to "NOT" completely seal the container. The L.N. will build up unsafe pressure in the tank if it is completely sealed. If it has the proper cap, just remove it, slowly put your blades in and put the cap back on the tank. If you want, send me an e-mail and I,ll tell you how I set mine up.
Roland

 

[mete]

Proper HT + LN bonus.

 

[F. Allin Kahrl]

Our cryo rig at work has process computer that introduces the LN2 slowly and takes about two hours to get the vessel (and parts) from ambient temperature to completely submerged. I've heard that this avoids the Evil Thermal Shock. Our parts aren't choppers but they get their fair share of abuse (and they have to be dead flat; ugh).

I've also heard of putting parts in a beer cooler with a block of dry ice and submerging them in kerosene to get a similar effect.

-Allin