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  • Users: Metalguy
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  1. Metalguy

    Cast Alum Fatigue Crack , But No Fractographic Evidence

    Have a baffling problem involving the sudden fracture of a motorcycle fork tube. The fork is cast alum. alloy, composition unknown. The fracture surface was not damaged during the event, but there is no "classical" evidence of any fatigue cracking, visually, under a stereo microscope, and...
  2. Metalguy

    Strange Spheres in Journal Bearing Oil

    We have recently found some tiny (5-12 micron) somewhat spherical objects in the journal-bearing oil of a large pump. They are primarily Fe, with some C and O. Previous oil samples have never found these. The oil is a simple R&O (rust and oxidation resistant) oil, and the bearings are...
  3. Metalguy

    Your Favorite SEM/EDS?

    Got a new "leader" at work, and it looks like we may finally be getting our own SEM. It will be used primarily for met. failure analyses. I've seen others use a few over the years, and they seem to have better features every time I look. SO, what's your favorites, and what do I make sure we...
  4. Metalguy

    Differential Oxygen Pitting in Admiralty Brass Tubes?

    I am in the middle of a failure analysis of some admiralty brass heat exchanger tube pitting. The water source is some huge open spray ponds, so anything can and does blow in. It is treated with a few biocides, and the Cl- is ~2,000 ppm. I expected to find some involvement with MIC, but have...
  5. Metalguy

    Eddy Current Testing---2205

    To continue this topic in the correct forum, I need help in convincing my NDE guy that meaningful ET can be performed on 2205. I want to use this tubing for retubing 6 2500 tube heat exchangers, and he is the biggest obstacle. Problem is he is a real ET heavyweight, at least on Alloy 600 steam...
  6. Metalguy

    Daltons Law Explained

    Here's the question. A very common MIG/GMAW welding gas mixture is 75% Ar and 25% CO2. We know that at temps. below ~89 deg F a cylinder of CO2 will have both liquid and gaseous phases present if the pressure is higher than some psi (I think it's around 900 psi). Now, if we have a cylinder...
  7. Metalguy

    4140 Threaded Stud Failure

    Had a somewhat strange failure recently that I had to do the analysis on. The stud is 1/2" dia A-193-B7. Operated for years at ~475 deg F. During removal from the valve (room temp)it snapped off. 100% brittle cleavage fracture. Did the usual checks-small grain size, normal chem, Rc28, only...
  8. Metalguy

    Tolerances on Mech Drawings

    Many years ago when I took a HS course in mech. drawing, the correct way to show dimensional tolerances was to have the same number for the + and - eg., if you want something between 7 and 9 in. long you used 8+/- 1 (I can't figure out how to get the + directly above the - here). But the...
  9. Metalguy

    Heat Rejection of Alum

    I am trying to find out if a black anodized piece of die cast alum. will reject heat faster than a plain polished piece. heat cond. won't be a factor here--it's radiation vs convection. I am aware of the importance of the actual temp. for radiation heat loss, but for this case the temp. is...
  10. Metalguy

    SMAW Welder Qual.-RT vs Bend Tests

    Anyone have good data on welder qual. pass/fail results for RT vs. bend testing? Materials are P1 and P3 steel, ~0.5" to 1" thick. Typical weld indications are slag, not porosity/cracks, etc. We presently use only bend tests, but have too much slag in production welds. Will making the...
  11. Metalguy

    Diameter changes in a horizontal cylinder

    I am trying to find the equation for the amount of weight-sag in a large round carbon-steel horizontal cylinder. If a cyl. is round when its axis is vertical, the diameters will change when the axis is horizontal and the bottom of the cyl. is on the floor (cyl. will become shorter vertically...
  12. Metalguy

    Slow Reading Fuel Gages

    Just wondering how/why the fuel gages of many cars respond so slowly. As I understand things, the tank unit is just a variable resistor and the dash gage is a volktmeter or ammeter. SO, why the very slow response? I know WHY slow response is good; I just don't know how it's done.
  13. Metalguy

    Start-Search-Files in W2000

    Any ideas on how to fix a W2000 problem of no "Start-Search-Files/Folders" capability? Do NOT want to perform a clean reinstall, and a the simple install-over-existing doesn't fix the problem.
  14. Metalguy

    Multi-pass submerged-arc welding

    We are performing a lot of multi-pass submerged-arc welding (SAW) of low-alloy steels (P3), and are getting too many small slag inclusions in the welds. What would be the most likely causes of this: failure to remove all the burned slag from the previous pass, a problem with the...
  15. Metalguy

    Anyone know why my "clip-around" AC

    Anyone know why my "clip-around" AC ammeter shows 2 slightly different readings depending on which of the 2 wires I clip-around? I've seen as much as 10% difference.
  16. Metalguy

    Motor oil in auto trans?

    Does anyone have any info on the use of motor oil (especially synthetics) in an auto trans, such as a GM 4T60E? Most motorcycles use a wet clutch similar to those in a car automatic, and the engine oil is also the clutch oil. Motorcycle oils which do not have "friction modifiers" are...

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