On 2/5/21 3:28 AM, Richard Smith wrote:
Joe Gwinn writes:

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

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
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

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.

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/...ng%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

Carl writes:

... ... ...


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/...ng%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

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.

On Fri, 05 Feb 2021 08:28:07 +0000, Richard Smith
wrote:

Joe Gwinn writes:

On Thu, 04 Feb 2021 11:43:58 +0000, Richard Smith
wrote:

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
???

Propane boils at -42 C at atmospheric pressure.

Joe Gwinn

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.

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

"Joe Gwinn" wrote in message
...
....
Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol.
....
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

---------------------

The pipe fitting that enables making a condenser or similar concentric tube
structure is a pipe reducer with the smaller end bored through on a lathe.
Brass is easier than copper to chuck and turn. A 6-jaw chuck helps hold the
reducer without (much) distortion, or you can jam a fitted wood plug into
the large end.

When I learned industrial refrigeration in the 1970's this is what we brazed
joints with:
https://www.amazon.com/Lucas-Milhaup.../dp/B06Y1N5517

"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.

On Fri, 5 Feb 2021 17:40:49 -0500, "Jim Wilkins"
wrote:

"Joe Gwinn" wrote in message
.. .
...
Have liquid propane in the sealed copper boiler with a tube going
uphill to a copper condenser cooled by dry ice in alcohol.
...
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

---------------------

The pipe fitting that enables making a condenser or similar concentric tube
structure is a pipe reducer with the smaller end bored through on a lathe.
Brass is easier than copper to chuck and turn. A 6-jaw chuck helps hold the
reducer without (much) distortion, or you can jam a fitted wood plug into
the large end.

I don't visualize this.

What I was thinking was a simple one-pipe system, with vapor going up
and condensate running down. The propane inventory need not be large.


When I learned industrial refrigeration in the 1970's this is what we brazed
joints with:
https://www.amazon.com/Lucas-Milhaupt-95150-Sil-Fos-Brazing-Alloy/dp/B06Y1N5517

Yeah, that's the stuff.

If you braze all the joints, you can hermetically seal the propane
inside the heat pipe. Make sure that the total volume is large enough
to prevent overpressure damage at room temperature. Or provide a
pressure releas valve and refill before each use.

Joe Gwinn

On Fri, 05 Feb 2021 08:36:21 +0000, Richard Smith
wrote:

"Jim Wilkins" writes:

"Richard Smith" wrote in message ...

.....
Yup, I know that as a PhD level scientist I have to work as a welder
...
Rich Smith
--------------------------------

...
tech made a bumper sticker "Techs can do what engineers only dream
of".
...

LOL ;-)
"Techs keep Engineers out of trouble!"

"Jim Wilkins" writes:

...

---------------------------------

During a winter power outage I found that a mix of snow and road salt
(NaCl + ?) fell to 5F, -15C.

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/stru...cfwtt_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.

"Richard Smith" wrote in message ...

"Jim Wilkins" writes:

...

---------------------------------

During a winter power outage I found that a mix of snow and road salt
(NaCl + ?) fell to 5F, -15C.

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/stru...cfwtt_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.

"Jim Wilkins" writes:

http://physics.wm.edu/~labs/110/110_pdf/ch4.pdf
If the metal permanently deforms some of the kinetic energy converts
to heat.

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/m...tS_htbarr.html
"Insert plates" so knocking it over again would be a long energy
consuming process.