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  1. Metalhead97

    steel microstructure after heat treatment

    bearingsteel, Is this a reconditioned roller or a new part? Do you know what condition the material was in before the heat treat cycle? MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  2. Metalhead97

    will grounding prevent aluminum corrosion?

    macPT, In just H2O, the Al2O3 coating is pretty stable. Halogens in solution will destabilize the oxide film and initiate corrosion. Grounding the Al plate, would place the plate at the potential of the surroundings and that would only facilitate charge flow and not hinder it. Get a car...
  3. Metalhead97

    steel microstructure after heat treatment

    bearingsteel, Please provided the steel composition (I'm guessing AISI 52100) and magification. All I can see are carbides and no contrast from individual grains. Thanks MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  4. Metalhead97

    Wear between steels and an Aluminum Bronze

    ttwowaymonologue, When testing is carried out in air, the oxides that form on the surface play important roles. The superficial hardness of the wear couple dictates the real contact area and the extent of plastic contact (the plasticity index). The real contact area controls how much force can...
  5. Metalhead97

    Measuring the Resistance in a Rod to Indicate Cracking?

    mfgenggear, I cannot comment on the absolute flaw size that is detectable because it depends on the frequency, probe size, and technique used. If the probe is fixed you don't have to worry about any lift-off effects and the only changes (in terms of impedance) you will see on the scope are due...
  6. Metalhead97

    Measuring the Resistance in a Rod to Indicate Cracking?

    I think one of us mentioned using Eddy Current tests. Go here to get more info: Link MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  7. Metalhead97

    Copper Furnace Brazing

    wayneter, How are you preping the surfaces prior to brazing? I would degrease followed by a activation/acid-dip to remove the surface oxide films. In the brazing furnace back-fill a N2/H2 (3-5% H2) reducing atmosphere several times. During the brazing process, the copper should remain bright...
  8. Metalhead97

    Thin membrane at high temperatures

    Marsh91, Since beryllium has little solubility in Al the beryllium phase will oxidize just like elemental beryllium. My suggestion is to talk to an application engineer at Materion about toxicity concerns. MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  9. Metalhead97

    Thin membrane at high temperatures

    There is a company called Materion that commercialized these alloys in wrought form. Might be a good fit as long as the temperature isn't too high. When I was talking about cooling I was referring to any cooling loads put on the part. MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  10. Metalhead97

    Base Metal Grouping

    LinkLink Those should help MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  11. Metalhead97

    Thin membrane at high temperatures

    Marsh91, Have you checked out the Al-Be MMCs? Might be a little low on the temperature requirement though, however I wouldn't think the metal component would actually reach the temperature of the exhaust if it's being cooled. MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  12. Metalhead97

    Should engineering faculty be licensed?

    I've had some really good and practical professors who were never licensed. The reality is that many engineers in my field are not licensed and industry doesn't institute licensing requirements. As a result, there is no motivation to get a PE for materials engineers. Also, I'm not convinced that...
  13. Metalhead97

    Measuring the Resistance in a Rod to Indicate Cracking?

    The plastic deformation effects from the bending can be separated out using a reference sample. For instance, you can run two simultaneous tests (sample plus known reference inspected by eddy current, ultrasound, etc.). You will get two V-out values at the exit leads, which are fed into the...
  14. Metalhead97

    Measuring the Resistance in a Rod to Indicate Cracking?

    chrisperry12345, The resistance changes are going to be determined by the constriction resistance associated with the crack, which goes rho/2a where a is the diameter of the constricted area. That calculation is for circular constricted geometries, but you might want to dig around for other...
  15. Metalhead97

    Wear question

    unclesyd, How much contact resistance does a Magnitite coating give you? I ask because the OP needs a stable electrical contact during a sliding application. When semi-conductors start wearing the contact resistance skyrockets due to constriction effects, which results in a noisy contact. MH...
  16. Metalhead97

    Spline fretting wear pattern

    Driller, You said yourself that the concentricity of the female spline with the OD of the shaft it rides on is the type of misalignment that's a concern for you. Does the female spline shaft appear to be wearing evenly? MH http://www.linkedin.com/pub/luke-autry/1b/510/566
  17. Metalhead97

    Galling question about 718 inconel and 17-4 1025 or h1075

    aroundhere, It's interesting that you would go from a low alloy steel with a BCC matrix to a IN718 with a FCC matrix when 17-4 PH is FCC- especially when 17-4 and IN718 have roughly the same hardness ranges. Was it done for the corrosion resistance? You could try chrome plating the 17-4 PH...
  18. Metalhead97

    cast iron on 410 stainless steel friction coefficient

    beginnerfeaeng, You can get an upper-bound on the adhesive wear contribution to the coefficient of friction by using the Tabor Junction growth formula if you know something about the interface strength and the yield strength of the least hard material. Abrasive wear coefficients can be...
  19. Metalhead97

    Spline fretting wear pattern

    driller, One of your biggest problems is that your female spline shaft has a 35 RC hardness. That shaft will wear quite a bit and create a lot of abrasive debris during the process. As soon as the female spline shaft starts wearing significantly you move away from your design conditions. Going...
  20. Metalhead97

    Heat transfer in vacuum

    Sounds like something right out of Poirier-Geiger! MH http://www.linkedin.com/pub/luke-autry/1b/510/566

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