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  1. Christian62

    Water Vapor Transmission Rate (WVTR)

    Well btrueblood, we test our plastic when they hit below 100ppm RH. They are put in the jar at about 50ppm. So if I knew what was GMS I could calculate how much moisture can cross this type of plastic (our lab is at 50%RH - 23C)and how long I can keep the product dry (below 100ppm. If the...
  2. Christian62

    Water Vapor Transmission Rate (WVTR)

    Hello All. A supplier of polymer bag is rating their product for WVTR at 0.048 GMS/100SQ INCHES/24 HOURS. A) What is GMS ? B) Will this be able to replace the Masson Jar we are using now? Note: We keep dry pellets in Masson Jar so the %RH is kept constant. We do this so can measure the...
  3. Christian62

    Surface Wear Effects on Shot Peening

    Well, If coating is impossible (lubrified liner etc. on your part or the other part) then use a peening that induce deeper compressive stress. You can look at LPB (Low-Plasticity Burnishing) or Laser Peening or Water Peening. Good Luck
  4. Christian62

    Texture in metal

    CoryPAd, I stand corrected ! Thank you. 1) Poisson is only relevant in the elastic zone like noted. 2) the R factor is obtained in a similar fashion has the Poisson's ratio but in the plastic domain. (we test for it in my lab) 3) So to connect this with texture I could simply point that the...
  5. Christian62

    Texture in metal

    I would like to add my two cents to Mcquire's very well vulgarized explanation (I should have been more to the point...) A) Textured material show anisotropy has noted. B) Because all grain structure have anisotropy! C) So if one could force all the grains to have the same preferred...
  6. Christian62

    Texture in metal

    Short answer: Texture is the &quot;generel&quot; grain orientation of the material under investigation. So for exemple in stainless steel the lamination process (cold work) will favor the principale orientation componant of {011}<211> (to a max of 25 to 1). And since the mechanical properties...
  7. Christian62

    Length of coiled metal...

    Hmm! .. aluminumphil! There must be a mistake in the formula or my calculator is broken? The above coil would give: R = 12&quot; r = 8&quot; t = 0.031&quot; L = 0.031 / pi * (12²-8²) L = 1.2 e-4 ??? May I suggest this: L = pi * (R²-r²)/t here you will get L = 8107 &quot; or 676 ft ...
  8. Christian62

    Coil hold down forces and energy

    Thank you all for your suggestions, I've done some theoretical calculations that are hmm questionable. I might finally go to an instrumented piston or ... I'm still looking. As soon as I get some good results I'll let you know. (I'll look at the deflection) Christian P.S. if you ear anything...
  9. Christian62

    Coil hold down forces and energy

    I could simplify the problem further (maybe to much?) We process flat material so it would be more like a spring clock (has suggested by Rich) with the last wrap functional. The other wrappes would not be functional because the internal friction of the steel keeps it from pulling. So I am...
  10. Christian62

    Coil hold down forces and energy

    Well, We take 0.250&quot; thick by usually 48&quot; wide strip of stainless steels and run it throw a cold mill to bring it to a lower thickness and improve its mechanical properties (yield, UTS,...). At the end of the mill the strip is wrapped around a mandrel and builds up until the strip is...
  11. Christian62

    Coil hold down forces and energy

    Hello Fellow mechanical eng. I need an easy way to calculate the hold down pressure or strapping strength required to keep a coil wrapped. The variables are: Coil diameter, Thickness of material, Width of material, Yield strength, Ultimate strength, Modulus of elasticity, Poisson's ratio...
  12. Christian62

    Testing Flat SS 30114: breaking out of the 2&quot; gage length

    Well, My reply is very late but... tada! I have (I think) the answer: (Sorry it's a little long) I did a LOT of tests (based on your info.. thank you) and after a lot of failures (our ration of good was low) I finally decided to change the tool (knife) that was machining our samples. I moved...
  13. Christian62

    &quot;Blue&quot; Stainless Steel.....

    Hmm, I looked for SAE420! I must have the wrong book! Maby ASTM 420 ? But 7C27Mo2 is a martensite Stainless Chromium Steel. So Annealing is around 1500°F to 1600°F and Process anneal is from 1200°F to 1400°F. But close to 800 I would wory about Carbides (precipitation from 900°F to 1700°F) that...
  14. Christian62

    SEM/EDS analysis in determining types of materials/coatings

    Hmm, In all the contamination analysis that I did performed and contracted to get done I always stay very skeptical of any ONE source analysis. You have to get to the contaminant by different routes and they should merge, then you have an idea of what is your contaminant. A) A max of info on...
  15. Christian62

    Your interpretation of this EDS analysis

    Good morning, EDS is a nice tool for elemental analysis but it can't say what is bonded to what! The Oxygen could be almost entirely bonded to the C (organic contaminant) and that would solve your question. You need at least an XPS analysis and if you have money a SIMS. These will really give...
  16. Christian62

    Magnetic Property of Austenitic Stainless Steel

    I know it is an old thread but I wanted to give my 2 cents! We make a vary wide variety of stainless grade and some are sold annealed or underannealed*. From our salt spray test I can say that the corrosion resistance of the underannealed material is lower than it's annealed chemical twin. So...
  17. Christian62

    Testing Flat SS 30114: breaking out of the 2&quot; gage length

    We test thousands of flat Stainless steels (>50 variations) and the only one that breaks out of the extensometer's 2&quot; gage length are some types of 301 SS. They break at the beginning of the reduce section; where the necking or shoulder joins the centre part of the mechanical test sample...

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