A couple of comments regarding metals, and the effects temperature on crystal structure, and the possibility of bull hockiness.
There are metals out there whose properties are cryogenic temperature sensitive. Iron/steel is one, as is tin and many others. It would not surprise me that many of the metals used in tubes are will change crystal structure when held at low temperatures, (I am not sure if your freezer qualifies for low temperatures other than maybe iron and tin ).
Do a search for "tin disease". You will find that tin changes crystal structure at common temperatures. Thus, a pipe organ and its pipes needs to be in a building where temperatures do not fall to freezing point of water. Given the position of Lead on the periodic table to Tin, I would say our friend Pb, may be also be subject to a "Lead disease"
do a search for "liberty ships", and you might find these WWII era ships had a bad habit of splitting in cold waters of the north Atlantic. the iron/steel went from a ductile to brittle fracture mode, so stress at rivet holes would result in catastrophic failure.
If you look at how tubes are made, tubes and the metals are subjected to high temperatures to degas the components. Are these temperatures high enough to change the crystal structure of the metals. Most likely. Upon cooling, will some of these metals retain metastable crystal structures. Most likely. (Need to look at the ttt diagrams, (time temperature transformation).
It is my understanding that under the Reagan era, It was thought, one could transport weapons grade material by rail. The propensity of steel shells to go from ductile to brittle fracture modes, derailed the idea.
Are tubes operated at temperatures high enough to modify those metastable crystal structures. again one would have look at TTT diagrams to determine the changes.
What happens at cryogenic temperatures? will there be crystal structure changes?. Again, one needs to find TTT diagrams for those tube metals. I would say this is a likely case. When I was studying metallurgy almost a half a century ago, the TTT diagrams for cryogenic temperatures were extremely rare. I would look to ASTM publications. (likely only available at those universities where material science is taught).
Is it really bullhockey? No, can it be bullhockey? Of course, if someone purposely wants to miss lead.
Lacking cryogenic TTT diagrams, If you have a metal whose crystal structure changes from room temperature to melting, I would suspect, the metal might be subject to crystal structure changes upon cooling.
best regards.
Topic: What tube is this? (Read 5928 times)