Get -40C in my fillet weld tensile break tests

Ideas to get a controlled temperature of around -40C (also -40F) in a test sample?
"Robustly" by physics: 100C -> boiling water
0C -> ice -17C -> brine-ice slurry (?) ??? -40C ??? -80C -> "cardice" - solid CO2 -196C -> liquid nitrogen
Reason is, found a way to tensile-test fillet welds, and so far always seeing breaking strength come out at around 560MPa, when you do the maths relating breaking force to the fracture area.
The 355MPa yield of the Rectangular Hollow Sections (RHS) isn't seen - and I know they have exactly that yield stress from beam bending measurements.
Here's the tests - "Alladin's Cave" of misdemeanours and skulduggery ? ;-)
http://www.weldsmith.co.uk/tech/struct/struct.html "Steel Structural Performance index-page"
Various tests.
Specifically the fillet weld tensile tests
http://www.weldsmith.co.uk/tech/struct/201124_fwbeamt/201124_fwbeamt.html "Fillet welds tensile tested in beam test"
http://www.weldsmith.co.uk/tech/struct/210122_fwtest_rig/210122_fwtest_testrig.html "Tensile-test rig for beam-configuration fillet-weld samples"
Movie of - 10 seconds - shared on "Dropbox" https://www.dropbox.com/s/esgwfk5jenhm024/210122_fwtr.mp4?dl=0
Yup, I know that as a PhD level scientist I have to work as a welder because everyone already ensconced in "office engineering" jobs manicured in their white shirts sees me as a "Dennis Hopper like" (think eg. "Blue Velvet" (1986) film) character of the science and engineering world ;-) If you keep the office door closed to all but your own manicured kind, you can keep reality out. Who can blame them if no-one comes and hurls them out into the cold hard world their scheme avoids? :-)
It would be helpful to see whether that "no yield event - straight to local fracture at high(er) stress" is associated with a low temperature brittleness charactistic.
I could "dam-off" the RHS close to the weld and at the far end, and fill it with a cooling fluid. Ice-brine looks good for -17C.
Throw a blanked over the entire sample for a while for all parts of the sample to be at that temperature, then slide in the hydraulic cylinder and "pump it up" and see what the temperature causes or does not cause.
What about for -40C ???
Regards, Rich Smith
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"Richard Smith" wrote in message
Ideas to get a controlled temperature of around -40C (also -40F) in a test sample?
The lowest setting on my Alpicool C20 DC-powered freezer is -40C. Temps below -20C are accessed with the E1 special setting. (Amazon.com product link shortened)
It works well enough but isn't as rugged or hands-off reliable as a normal AC-powered freezer, and really should have thicker insulation.
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"Jim Wilkins" wrote in message
Ideas to get a controlled temperature of around -40C (also -40F) in a test sample?
---------------------------- The lowest setting on my Alpicool C20 DC-powered freezer is -40C. Temps below -20C are accessed with the E1 special setting. (Amazon.com product link shortened)
It works well enough but isn't as rugged or hands-off reliable as a normal AC-powered freezer, and really should have thicker insulation. ------------------------------------------ I confirmed it could be set to -40C but didn't leave it there, as it's full of food and would have taken a long time to settle.
My Alpi wouldn't quite cool to -20C in a hot car so I made an insulated enclosure for it, 1" foam lined inside with a yoga mat to catch and drain summer condensation. The exterior is thin birch plywood joined at the corners with sheet metal angles inside and truss head screws. The lid is a flap of Harbor Freight moving blanket, doubled.
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wrote:

Propane boils at -42 C at atmospheric pressure.
Joe Gwinn
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"Joe Gwinn" wrote in message
Propane boils at -42 C at atmospheric pressure.
Joe Gwinn
------------------------------- I checked the weather on Spitzbergen to see if the experiment could be done at ambient temperature there. https://www.accuweather.com/en/sj/longyearbyen/310461/weather-forecast/310461
Funny, New England USA was that cold over the weekend, and we are at the latitude of Spain. https://brilliantmaps.com/cities-transposed-latitude/
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Spitzbergen idea - LOL !
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On Friday, February 5, 2021 at 3:02:33 AM UTC-5, Richard Smith wrote:

That must mean that the tip end of Narragansett is about the same average temperature as the well known shores of Spain in the summer time.

Wow, images of Spitzbergen are nice. I get words like Spitzbergen and Zugspitze (the highest mountain in German, literally translated as "train peak") mixed up.
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"Transition Zone" wrote in message

That must mean that the tip end of Narragansett is about the same average temperature as the well known shores of Spain in the summer time.

Wow, images of Spitzbergen are nice. I get words like Spitzbergen and Zugspitze (the highest mountain in German, literally translated as "train peak") mixed up.
---------------- Away from the coast the summertime highs here are quite close to Madrid's, 35C and above.
I rode the cable car up the Zugspitze and yes, it's spectacular.
My best memory of European mountains was flying low over the lesser-known Swabian Jura (Alps) between Stuttgart and Augsburg in an Army helicopter with a view straight down. Probably the worst was riding a speeding, tilting van up the winding road to Hohenzollern castle and feeling like we were about to fly off the road and tumble down the steep slope.
Emperor Frederick the Great was there, in a plain wooden coffin on sawhorses in the castle's entrance.
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Thanks for suggestion. Well rooted in science. I fear that as the sample gets colder with propane evaporation, we could get a hair-trim if the evaporated gas ignites.
The sample halves hurl around on sample weld breaking, so putting on a "vent tube" with the propane burning at the outlet - a "flare" - doesn't seem a viable solution.
It might be that I have to do something with "cardice" - solid CO2. Throw-in bits until reaches -40C.
Or cool to lower temperature and pump the cylinder when weld area has is showing -40C by thermocouple.
Thanks for suggestions.
I just looked online and find https://en.wikipedia.org/wiki/Brine that lowest melting point is -21.1C
Something you learn about experimenting - while you do make sure everything holds together as it should, you don't look for the n-th degree of accuracy of physical conditions in the proof-of-concept tries.
To think in planning that a particular exact temperature is important is the error of thinking that if you specify something enough, "God" has to conform. Not going to happen. Get a pretty cold temperature and observe what is there to observe.
Regards,
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"Richard Smith" wrote in message ... Or cool to lower temperature and pump the cylinder when weld area has is showing -40C by thermocouple.
-------------------
That's the first method I would try, to check your assumptions and procedure and shrapnel containment.
This suggests that impurity levels might be a significant uncontrolled variable in your experiments: https://www.tf.uni-kiel.de/matwis/amat/iss/kap_9/illustr/s9_1_1.html
Is -40C the lowest you expect in European service? https://en.wikipedia.org/wiki/Operating_temperature
Some industrial temperature controllers have a cooling option that can operate a solenoid valve to regulate the temperature with evaporating CO2 from a tank of room-temperature liquid. https://www.linde-gas.com/en/processes/freezing_and_cooling/index.html
If the test chamber is nearly sealed the escaping gas should reduce or prevent frost covering the sample. US regulations required an oxygen level sensor and alarm at the test station. The body's breathing mechanism responds to CO2 level (pH) in the blood, not oxygen level, so you may not realize you are about to pass out from anoxia, especially with liquid nitrogen.
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On 2/5/21 3:28 AM, Richard Smith wrote:

There are lots of other things besides sodium chloride to make "salt" baths from :-). See https://en.wikipedia.org/wiki/List_of_cooling_baths for one list, and look at reference 2 and the reference pdf in ref 2 (https://www.larkinweb.co.uk/science/2010/files/Cooling%20baths.pdf ) for a bit more info. I'd try calcium chloride hexahydrate/water either at the ratio for -41C or a bit stronger since they say it is difficult to reach the listed temps. You could also precool your metal with dry ice and even add some dry ice to the salt bath while it is cooling down, or put the salt bath in a small tub in a larger tub with dry ice packed around it. I'd make the starting ice either from distilled water (cheap at grocery stores) or reverse osmosis water if you have a home system already. If having the metal dripping with wet calcium chloride is a problem during your test put the piece in a ziploc bag. Partially seal the bag so about an inch at one side is still open then slowly submerge the bag in plain water while holding that corner out of the water. The air will be forced out so you get good contact between bag and metal for good heat transfer. Finish sealing the bag when as much of the air as possible is removed. Just pretend it is a steak you are about to cook sous vide :-).
--
Regards,
Carl

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Stunningly good info. Thanks.
I could see what NaCl-brine-ice does for the test, knowing there's further I could go.
Dam the ends of the Rectangular Hollow Sections to hold the brine-ice internally = direct contact. Contained. Salt on the sample wouldn't matter anyway.
Many thanks again.
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"Richard Smith" wrote in message
I could see what NaCl-brine-ice does for the test, knowing there's further I could go.
---------------------------------
During a winter power outage I found that a mix of snow and road salt (NaCl + ?) fell to 5F, -15C.
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Real deal. Thanks for that.
BTW
Mind's been going crazy over this. Spent yesterday Finite Element Analysis modelling the "beam-configuration fillet-weld tensile test" http://www.weldsmith.co.uk/tech/struct/210205_bcfwtt_fea/210205_bcfwtt_fea.html "FEA : beam-configuration fillet-weld tensile test" Just occurred to me - if kept tubes strictly straight in-line with a frame/guide - could make it a longitudinal tensile - which means you could fast-load by firing a weight into a "stopper-plate" in the line of the sample. etc. etc.
If this sounds fanciful - every step of one of these home-spun investigations seems fanciful, each "next summit" seeming barely likely to happen. I could say this about this series of mini-projects so far, my fatigue-resistant welds research, my Doctorate studying then-new TMCP steels from Germany and Japan (definitely!), etc.
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"Richard Smith" wrote in message writes:

Real deal. Thanks for that.
BTW
Mind's been going crazy over this. Spent yesterday Finite Element Analysis modelling the "beam-configuration fillet-weld tensile test" http://www.weldsmith.co.uk/tech/struct/210205_bcfwtt_fea/210205_bcfwtt_fea.html "FEA : beam-configuration fillet-weld tensile test" Just occurred to me - if kept tubes strictly straight in-line with a frame/guide - could make it a longitudinal tensile - which means you could fast-load by firing a weight into a "stopper-plate" in the line of the sample. etc. etc.
----------------------
http://physics.wm.edu/~labs/110/110_pdf/ch4.pdf If the metal permanently deforms some of the kinetic energy converts to heat.
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Resilient design - make sure that in an extreme event, there's not-a-lot / no abrupt breaking (low energy and structure is lost) and a lot of distributed bending and deformation (high energy, and the structure is still there)... :-)
Job as a welder - repair a height-restriction barrier at a supermarket http://www.weldsmith.co.uk/dropbox/my/engr_tott_htbarr/070413_TottS_htbarr.html "Insert plates" so knocking it over again would be a long energy consuming process.
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"Richard Smith" wrote in message writes:

Resilient design - make sure that in an extreme event, there's not-a-lot / no abrupt breaking (low energy and structure is lost) and a lot of distributed bending and deformation (high energy, and the structure is still there)... :-)
Job as a welder - repair a height-restriction barrier at a supermarket http://www.weldsmith.co.uk/dropbox/my/engr_tott_htbarr/070413_TottS_htbarr.html "Insert plates" so knocking it over again would be a long energy consuming process. --------------------------------
Around here bollards that are expected to stop vehicles to protect buildings are 4" nominal pipe set in and filled with concrete. 4" pipe is actually 4.50" OD, and I acquired some free 3.5" pipe which is 4.0" OD and was mistakenly cut and painted yellow to be bollards.
The pipe came with an 8' x 10' wooden shed a neighbor bought at a yard sale and brought home on his flatbed equipment trailer. He and his construction-worker friends had used it as rollers to muscle the 2400 lb shed onto the trailer. Then I was enlisted to hoist the shed off the trailer and lower it onto its new foundation. The pipe may be useful as rollers this spring when I move a 4000+ lb oak log off the hillside where it fell and to somewhere flat enough to set up my sawmill.
When I was building custom industrial machinery we muscled as much as 5000 lbs onto the truck. That's about the average weight of a stone in the Pyramids. Customer [XY] had his just-delivered machine up on a forklift when the break time buzzer sounded and the crew just left it there. When they returned the machine had fallen flat on its face and the forklift was standing up on end. I salvaged a bucket of electro-mechanical components like Variacs from the rebuild.
I was in line (queue) at the industrial supply store behind an inventor/engineer who was picking up the 2" ID bearings he had special ordered for the 2" water pipe support on his tracking solar array. He was very unhappy to belatedly discover that 2" pipe isn't anywhere near 2.0" in diameter. I warned him that although the specified OD is 2.375" it isn't truly round unless cleaned up on a lathe, which removes the protective galvanizing.
I machined the thrust bearing for my solar array from stainless plate and turned the ball race grooves with the sharpened back end of a carbide drill bit. The housing is a PVC pipe fitting.
This show why engineers and inventors need good techs. The designer of the Japanese Zero naval fighter complained in his memoir that a wartime shortage of competent technicians seriously hindered the development of its replacement, and their Navy depended on its pre-war design long after US fighters 100 Kts faster had made it a death trap. German designers made the same complaint, and I believe their late-war proliferation of scatterbrained schemes was self-preservation. Towards the end even U-Boot crews were being drafted as infantry for the Eastern Front. https://www.historynet.com/extremes-amerika-bombers.htm
https://en.wikipedia.org/wiki/Die_Glocke_ (hoax) Like every secret project it needed a misleading cover story. Segway leaked some whoppers to conceal what we were doing in the lab. To me the detailed description appears to be of a very powerful X-Ray source, a Death Ray against bombers, which unfortunately could only shoot straight up due to its parabolic rotating Mercury anode, Tungsten being too desperately needed elsewhere. https://en.wikipedia.org/wiki/Liquid-mirror_telescope The proof-of-concept demo would of course use visible light, not X-rays.
The special Mercury may have been radioactive waste left from the recovery of Radium metal by electrolysis, and perhaps the basis of "Red Mercury". The round structure above would have held a lens or mirror to aim the beam of X-rays, which is impossible with any known material, but ignorant street-thug Nazi officials wouldn't know that. A convincing zapping demo could be faked using a lens of silver chloride, which does focus equally invisible infrared, and makes a plausible excuse to acquire large amounts of the precious metal in a soft yellow/white form that could be smuggled into Switzerland as cheese.
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There's a need for a spectrum of people, for sure. Not the impression you get at the moment in the UK.
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"Richard Smith" wrote in message writes:

Resilient design - make sure that in an extreme event, there's not-a-lot / no abrupt breaking (low energy and structure is lost) and a lot of distributed bending and deformation (high energy, and the structure is still there)... :-)
Job as a welder - repair a height-restriction barrier at a supermarket http://www.weldsmith.co.uk/dropbox/my/engr_tott_htbarr/070413_TottS_htbarr.html "Insert plates" so knocking it over again would be a long energy consuming process.
--------------------------
A retired town snowplow driver told me that people who erect very solid steel roadside mailbox stands that don't protect people or property from damage have been asked to remove them before someone dies.
It's a difficult call, and I would make the part that breaks be easily replaceable.
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wrote:

One dodge is to make a heat pipe using propane as the working fluid, dry ice as the coolant.
Have liquid propane in the sealed copper boiler with a tube going uphill to a copper condenser cooled by dry ice in alcohol. The dry ice boils at -109 C, well above the freezing point of propane, so what will happen is that the propane will boil at -42 C, with the vapor rising to the condenser, where the propane will liquefy, and run back down to the boiler. This process is self-regulating so long as things are well insulated. But do this outside, and a 2-meter flare tube is a good idea.
The copper stuff can be ordinary plumbing tubing and fixtures. For a one-off, plumbers solder is good enough. For a true seal, braze with phosphorus-copper brazing filler, as used for HVAC systems.
Joe Gwinn
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