Why "Cryo" anything?

Is this some kind of set-up? Nobody dips anything into a cool solution. Almost everyone knows cryo treatment is a two-day affair. This is some sort of joke, right?

John,

the point I am making is that the starting phase of the steel must be in austenite. Once quench to to a lower temperature. Martensitic transformation occurs. Certain percentage of the marensite is formed, but the other material do not stay in Austenite phase. All the left over goes into Pearlite or Ferrite depending on compostion.

So any further quenching will not continue the martensitic transformation. The material must be raised back to a higher temperature level and reform Austenite before that's possible.

Put it another way. A piece of Steel can have a dramatic phase change by dropping rapidly from 900 to 20C, but that change is near permanent. Dropping the temperature from 20C to -150C do not continue the phase change. You must heat back up above ~800-900C to reform the inital Austenite phase.

The driving force for the martensitic transformation is the instable crystal structure of Austensite at lower temperature. So without forming austenite again. The driving force is gone.

For anyone who is interested, check out an example of phase diagram: (note that phase diagram changes rapidly depending on level of impurity.)

http://www.sv.vt.edu/classes/MSE2094_NoteBook/96ClassProj/examples/kimcon.html

For amorphous material like glass, the temperature change will mostly introduce lots of stress on the material. Eventually it formed a solid. The phase change most likely will cause physical breakage. Not sure what would be the audible effect, but I think the end result would most likely lower reliability.

Eric

""The driving force for the martensitic transformation is the instable crystal structure of Austensite at lower temperature. So without forming austenite again. The driving force is gone.""

The point is, at a specific temperature, austenite/martensite ratio will be stable, and lowering the temp changes that ratio to another, stable one..eventually, a temp is reached where all the austenite is gone.

Now, purchase a material, it is delivered, and in your hand..next, assume that what you have in your hand is not fully stable at the atomic level, and if you lower it's temp, a diffusionless process stabilizes the lattice..that is what the cryo process is all about..yes, heat was initially involved, but after you got the material, all you did was cool it..

It's that instability I'm talking about..the austenite to martensite transformation was the easiest example to use to explain diffusionless transformations..

It's the concept of a transformation that occurs as a result of cooling something that is important..

Cheers, John.

PS..be back in a week..on vaca...it's been a pleasure..

Howdy folks,

I'm new to the forum and cryo, but keen to learn more.
(I apologise if these have already been answered elsewhere.)

1) Is this cryo treatment physically (and audibly) reversible? ie. does the given un-cryoed component sound exactly the same as before? Ditto for a re-cryoed component?

2) Is it equally effective on components of varying ages/oxidations, or is it best done during manufacture?

3) Could its mechanism have something to do with altering micro-stresses, surface micro-cracks / imperfections, or driving out gaseous impurities? Is any change, say to copper wire, visible under an electron microscope?

4) Are the improvements positive in every aspect of the sound quality (eg. transparency, soundstage width or depth or height, grain, sibilance, fatigue, engagement, noise etc), or are most aspects improved while some others have no change or get worse?

5) I'm not very clued up about the DBT and ABX testing methodologies mentioned - wondering do any of these include AB testing where the ear is primed to say a short loop of music through A first repeated many times before beginning the random switching. Then prime the ear for B many times over and retest? Repeat above many times. The reason I'm curious is because in my limited not-very-scientific audio comparison tests I've found it's easier to a) hear a change after your ear has heard a given sound many times over and memorised it well, and b) hear an improvement rather than a temporary degradation. However, I find it's easy to be seduced by an improvement in one aspect of the sound while a perhaps bigger degradation in some other aspect slips through unnoticed (but rears it's ugly head in a long term test).

Cheers,
Lost_in_space

Let me try to answer some of them.

For 1 and 2, at normal operating temperature, (room temp to 100C), there will be not be any significant change to the internal structure of the material, but the surface of the metal can oxidize easier. Mechanical movement by twisting and pulling can cause more change in micro-structure than temperature at this range. For example, if the speaker cable design emphasize large grain micro-structure (Audioquest LGC), simply twisting the long cable will cause the long grain to break up into shorter grain structure. The effect can be worsen at lower temperature because the bonding strength is lessen at lower temperature.

So it's likely reversible, but the process can be quite complicated. I would think that material is best designed into manufactoring instead of some tweak.

3) Change in the stress of the metal will have to do with the Macro-structure or mechanical design. For example, a tight fitting metal o-ring undergoes cryo treatment only. The fitting might not be so good afterward because the overall shape have changed due to thermal stress cycle or thermal stress hysterisis. The micro-structure or material itself probably have not change that much.

4) Sorry. Can't comment on it.
5) DBT is very simple. Just make sure the listner and test giver do not know the actual test being run. For ABX, it's ok for the listner to get familar with the music passage first before the test. So, listen to A, listen to B and then listen to X. The listner writes down if the X is A or B. Repeat the same passage at least 10 times. If the listener can consistently get the correct answer 9 out of 10 times. It's statistically significant.

Very tough listening test in my opinion. I can't remember the difference that well. After 2-3 tests, everything sounds very much the same. It's also very impratical for multiple listner because of narrow sweet spot.

Eric