Too far gone; nothing worth having. Sad. The person who mentored me on my metal and fatigue investigation and knowledge told me the path to Thermo-Mechanically Controlled-Processed steels started when to get seriously far North in the North Sea the British engineers needed steels with exceptional properties and could see how that could be obtained. Apparently the British steel companies "took a sensible view about this fringe product" and the Japanese made these super-refined (compared to anything before) plate C-Mn steels. Then the development path and there they are, the Japanese and Germans, the established incumbents able to meet all market demand. Told me that - note that distinction.
It would have to be calibrated against another method.
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"An increase of the electrical resistance of the wires due to the cracks and an increase due to coldworking, could be measured as two distinctly different effects. No change in the resistance due to interstitial solution of hydrogen could be detected."
It would have to be calibrated against another method.
No change in the resistance due to interstitial solution of hydrogen could be detected."
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I'm still looking for cheap DIY methods. It appears that heavily anodized aluminum might be a good low permeability material for a chamber in which to pressurize steel samples with hydrogen and test sensors, and quickly evacuate the chamber, electrically heat the sample and measure the amount of outgassed hydrogen.
A vacuum chamber can be a piece of tubing with thick plate ends clamped by tie rods. The seals can be O rings in grooves turned in the tube ends.
On Tuesday, January 24, 2023 at 1:31:33 AM UTC-5, Richard Smith wrote: >Your "Raman Lidar" would work for a thin sample extracted from eg. a
I bet it could be done by freezing the welded sample down to liquid nitrogen temperatures, then hitting it with a high-power pulsed laser that instantly vaporized a small part of the surface, feeding the gases that came out into a mass spectrometer to detect the hydrogen. (Yes, optical detection is another possibility, but it might struggle with the low concentration, whereas mass spectrometers are good at detecting exceedingly small concentrations.) The process could then be repeated until the sample was entirely consumed and you had hydrogen numbers for each little piece of it. Or if that would take too much time you could take a representative slice through it.
Of course that'd be quite a formidable apparatus, requiring much money and years of work by several people.
I bet it could be done by freezing the welded sample down to liquid nitrogen temperatures, then hitting it with a high-power pulsed laser that instantly vaporized a small part of the surface, feeding the gases that came out into a mass spectrometer to detect the hydrogen.
Norman Yarvin snipped-for-privacy@yarchive.net
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It appears that the reason hydrogen in steel hasn't been studied is lack of instruments, not lack of interest. XRF is another analytical technique that doesn't work for it, or other light elements.
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The Fusor is a tabletop fusion reactor that emits neutrons.
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"Most recently, the fusor has gained popularity among amateurs, who choose them as home projects due to their relatively low space, money, and power requirements."
See [*] for a related technique (known in the 1930s and possibly earlier). [*]
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In the 2D case, "To approximate the solution of the Poisson equation ... numerically on a two-dimensional grid with grid spacing h, the relaxation method assigns the given values of function phi to the grid points near the boundary and arbitrary values to the interior grid points, and then repeatedly performs the assignment phi := phi* on the interior points, where phi* is..." 1/4 of sum of neighbor cells, less an f(x,y) term. Your case with two different D regions would mean using two different phi* equations, but I don't see that as a problem. Where the relaxation method (at least as stated in [*]) doesn't quite fit is that it starts with given boundary conditions and computes until interior point values reach equilibrium, while your process is given some initial interior values and evolves the state from there, not necessarily reaching a nonzero equilibrium.
Need to formulate DE's to have a model to be solved, but don't need analytical solutions if the computer can quickly approach a solution that's accurate enough and provides enough insight. (An example of slowness and limited insight: The writer of following ca 1950 thesis says it only took 7 hours to compute a relaxation solution for a heat transfer problem on 50 points. It probably would take a couple of milliseconds nowadays and there would be an informative graphic as well.)
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The mid-point method of numerical integration is not bad -- its error is O(h^3), for intervals of width h -- but Simpson's rule, for about the same cost per step, has far smaller error, O(h^5). Eg, where the midpoint rule might need hundreds or perhaps thousands of divisions to compute a 9-decimals value of erf(x), Simpson's needs fewer than 40.
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