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In Reply to: RE: Gonna ask this cryogenic question regarding soldering..... posted by unclestu on July 27, 2014 at 22:37:13
Actually repeated tempering does make the metal harder, and more durable, and allows it take a sharper edge. But it does not make the metal more brittle. It makes it less brittle. This is why the expert Japanese sword makers of yore could make such amazing swords (using repeated tempering). The swords were less brittle, not more brittle. To put it another way making the metal harder doesn't necessarily mean that makes it more brittle, although some materials like certain ceramics are very hard and brittle.
Edits: 07/28/14Follow Ups:
tempering lowers the hardness and increases the toughness of steel. Japanese swords weren't repeatedly tempered. Higher hardness generally means less toughness, more brittleness. From Wikipedia:
"Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to some temperature below the critical temperature for a certain period of time, then allowed to cool in still air. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product."
try it! you know you want to!
UncleStu says more brittle and Geoff says less brittle. This is an illustration of what's wrong with offering advise/knowledge on these forums - unless you are absolutely certain. Some advise/knowledge is plain wrong, and unless it gets noticed (and challenged), it remains on the page as truth. And then it becomes accepted, and then becomes dogma.
Edits: 07/28/14
For you to comment is utter foolishness IMHO. The process GK refers to is annnealing. Specific temperatures much be reached for the material treated and the case of steel be followed by quenching. Off the top, IIRC, some thing like 1500 F +. Steel would be heated red hot.
Now use your common sense. Soldering if you ever did some does not approach annealing temperatures. My temp controlled tips are 700 F rated. It is highly recommended by US Mil soldering manuals to use minimal heat and temperature.
Sheesh, bad enough to haveGK throw in unrelated issues then to have you stating an opinion without doing a minimum of research ( try googling annealing).
I should also point out repeated soldering and unsoldering involves a lot of flux, but I 'll recommend you research the role of flux and how it works (again try googling it).
The issue is one of hardness and brittleness of metals that may or may not result from Cryo and heating. I am referring to both cryo and heat tempering. Isn't that obvious? The OP was worried that heating the metal would destroy the effects of cryo. The answer is no, it wouldn't. However, now that I think about it, thermal shock is an issue for both cryo and heat tempering so I wouldn't try to make any judgements about the success or failure of cryo or heating with solder iron until about a week later. You also failed to grasp the implications of the NASA report, which actually answers the issues with copper and repeated cryo cycling and heat cycling that you were a little fuzzy on.
Edits: 07/28/14 07/28/14
Correct, and you seem to consistently miss the boat, so to speak. There is a significant difference between tempering and annealing (try googling them). You example of annealing for swords is so fraught with inaccuracies as to be totally worthless
Also your understanding of Japanese samurai swords is also flawed and erroneous.
The keenness of the blade is achieved through forging the blade and repeatedly folding over the alternating section of high carbon steel with regular steel (low carbon). By repeated folding and forging the sword becomes comprises of many hundreds of layer of alternating steel.
The high carbon steel gives the blade the sharp edge as with modern kitchen knives ( professional types). AFter forging the blade is then heated up to a light red color and then quenched. But this is done only after coating the cutting edge with some clay which gives the traditional swords that wavy visible coloration, This insures the blades retains its hardness from forging and then anneals the backbone of the blade to insure it does not shatter.
It is interesting to note that the blades are forged straight and the curvature is derived from the shrinking process of the steel when quenched.
When you look up Japanese sword blades, please also look up work hardening, a process every metal worker is intimately familiar with
I am not referring to forging, I am referring to tempering, heat tempering. Stop trying to put words in my mouth. Here is a simple explanation of heat tempered swords. This explanation also describes how to avoid brittleness while achieving hardness during heat tempering.http://www.strongblade.com/prod/pop_tempered.html
Cheers
Edits: 07/29/14 07/29/14
Look up Japanese sword making. Their swords are forged and
The applied heat is necessary to weld the folds. It is the many layers of high carbon steel alternating with low carbon steel which gives the sword its resilience and the sharp edge.
I do not believe you understand the process and seem rather desperate to salvage your obvious error and misunderstanding.
Nt
Language for you? It would explain a lot since it was YOU who used the example of Japanese swords.
LOL !!!!!
Unfortunately your mind is not. I used the Japanese sword making as an example of heat tempering. Then you went off the deep end with all the irrelevant forging nonsense.
You simply used a horribly poor example. Get over it.
Japanese swords was actually an excellent example of what I was trying to say about heat tempering and hardness and brittleness. Your efforts to recover your composure after bobbling the ball are duly noted.
Desperate aren't you. You think that simply repeating your errors will convince others that it is true. LOL !!!!!!!!!
All they need to do is to google Japanese swords, tempering temperatures and forging, to know your errors, as you do not seem to understand the differences. In addition, there are numerous books written about the subject exploring the process and metallurgy involved in making Japanese blades.
There is a fundamental difference why Japanese swords were much superior to the tempered blades of the middle ages, even of the famous Damascus steels ( carbonized steel by thrusting the red hot blade into the body of a slave, originally). You'll have to read up though, although I do understand that may be difficult for you to comprehend ( at least by your current comments). Most readers of AA are NOT illiterate and do know their way round the 'net....
Sheesh..........
Enjoy...
I was not doubting you specifically as you may have surmised, but merely pointing out the problem when there are two opposing views. I would guess that most readers (including myself) have no idea about brittleness in this context. Now that you have provided some background, there is less confusion. Thanks.
Edits: 07/28/14
OP is worried about the repeated effects of soldering and unsoldering. I pointed out possible effects on the base metal not the solder. Does the NASA study cover repeated soldering and unsoldering?
Seems to someone threw up a lot of trees and no.one notices the forest.....
LOL !!!!
I suspect you probably need to read the OP again. His question was very simple: would soldering the connector reverse the effect of cryo? He was NOT asking about repeated soldering and unsoldering.
Doh!!!!!!!!!!: Read further, he was specifically asking because he intended to experiment with various ends.
Damn, your reading comprehension is so poor, you shoot off before understanding the issue and before completely understanding what has been written. Then again, you have been very consistent in that regards.
AS I had advised over a year ago, please take the time to really read and then to reread your replies before pushing the send button. You wouldn't find yourself boxed in so often that way
Your NASA study for example:1. is testing the viability of cooling fin fabrication. Hmm different from wire obviously although copper tubes were used.
2. The solder was cyclically cryogenically treated ( necessary for spacecraft), but the joints were NOT removed and repeatedly replaced, as OP would obviously need to do of experimenting with different cables and wire.
3. Page 2: "A major disadvantage when using high tin solders is the brittleness of these solders when subject to temperature at and below their ductile-brittle transition temperature 0f 173.6 K (that's -148 F, yes minus 148)".
4. Table three on page 6: "solder wire connections became brittle and developed cracks resulting in noisy electrical output" No further explanation is given. Apparently from the same table, they tested 63/37 solder and a lead free 95 Sn/5 SB solder and cycled between 77.8 K and 355.6K 9 (-320 F to 180 F). The key is cycling, IMHO.
Edits: 07/30/14
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