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  • Users: AlanD
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  1. AlanD

    Scientific name for rust?

    >>What is the scientific name for rust or corrosion? How do you explain the delaminating of a steel beam that has been exposed to moisture. I need to talk to a group of kids about this, and I just don't want to say it rusted. What about the term "oxidised". The terms of corroded and rusted...
  2. AlanD

    Brightdip anodize 2011

    The 2024 has a lower copper concentration than 2011 which may be impacting on the ability to bright dip. My investigation didn't look at which which process (bright dip or anodizing) the copper was etched from alloy being anodized. But from memory, the black precipitate did initially form during...
  3. AlanD

    Brightdip anodize 2011

    At last something on my thesis topic. The quick reason why aluminum copper alloys are unsuitable for anodizing is that the copper is preferentially etched from the alloy during the anodizing process. If copper is in the grain boundaries, this etching will leave the structure weak and...
  4. AlanD

    MOOS hardness

    A quick google search would indicate that the Moos Hardness Scale the Russian equivalent to the Mohr's Hardness scale. It seems to have the same values for the same minerals.
  5. AlanD

    MOOS hardness

    I think you might mean Mohs hardness. It's a hardness scale used in the minerals field. Diamonds have a hardness of 10, Talc 1, and Quartz has a hardness of 7. Relatively, a pen knife will scratch anything up to 6.5 and a fingernail upto 2.5 on the scale.
  6. AlanD

    Aluminum to Stainless

    There are various paints and gels that can be used to electrically isolate the two metals. The one I'm currently using is called Tef-gel and should be available world wide under that name. Another product is called duralic, it's a yellow zinc chromate paint, but it might be known under a...
  7. AlanD

    Laser Beam Welding technique?

    It's gets a reasonable right up in my 1977 edition of the Sandvik Welding Handbook. In short, this new technology has been around for some time. It's applications are / were for precision welding situations, paarticularly in areas like electronics. At the time they thought it could take over...
  8. AlanD

    What is the difference between tempering and stress relief?

    From an old copy of "Definitions of Metallurgical Terms" by the The Australian Institute of Metals - 1971. Stress Relieving: Heating a metal to, and if necessary holding at, some temperature generally below the recrystallisation range, followed by uniform cooling, for the sole purpose of...
  9. AlanD

    Magnetized stainless

    It depends on the type of stainless steel being used for races. Austenitic stainless steels (2** and 3**) won't magnetise, but ferritic stainless steels and martensitic stainless steels (groups 4** and 5**) are magnetic. Precipitation hardening stainless steels and duplex stainless steels need...
  10. AlanD

    Aluminum for Anchors

    A third person showing showing caution. Anchors designed for sand or mud bottoms require mass to allow the fluke of the anchor to dig into the bottom and a length of chain to make the pull on the anchor horizontal across the bottom, so if the anchor begins to drag it will hopefully catch again...
  11. AlanD

    Bending aluminum tube

    Fill the tube with dry sand and seal the ends before attempting to bend. The sand helps prevent the tube crushing or kinking, but because the sand is lose it still flows allowing the tube to bend.
  12. AlanD

    Best way to epoxy Aluminum???

    Part of the problem with getting a good epoxy bond with aluminum is that the aluminum oxidizes almost immediately which means the bond isn't as good as it could be. With sailing equipment, we used to get this problem by using wetordry abrasive paper, but instead of using water as the wetting...
  13. AlanD

    mechanical properties of HDPE.

    Have you tried looking in Matweb? http://www.matweb.com/search/SearchSubcat.asp
  14. AlanD

    Slot Car Material Help

    Don't underestimate the strength of paper mache'. Helmets made from paper mache' were used as hard hats by cavers and climbers before plastic ones were readily available.
  15. AlanD

    Slot Car Material Help

    For a one off shell, this may make you laugh, but make a mold of the shape you want and then make the shell out of paper mache'. It should end up lighter, just as strong and easier to build than the equivalent in fibreglass.
  16. AlanD

    Properties of metals at Cryo temp

    My apologies everyone, I've been barking up the wrong tree. Please disregard everything I've posted in this thread.
  17. AlanD

    Properties of metals at Cryo temp

    I've probably said it poorly. Although other steel phases may be brittle or may lose their ductility with decreasing temperature, to the best of my knowledge they do not suffer a ductile to brittle transition which is temperature dependent. This phenomena is restricted to the austenite /...
  18. AlanD

    Properties of metals at Cryo temp

    >>What if I have a structure composed completly of Ferrite and Pearlite, that contains a relatively large amount of carbon? (Such that the steel could if quenched rapidly form martensite.) Would I then see a Ms and Mf? If I cooled low enough would I begin to form martensite? Discusssing in...
  19. AlanD

    Properties of metals at Cryo temp

    >>To add to the above post, the low temperature fracture properties of metals are governed by chemical composition, grain size, and heat treatment, to name just a few of the important contributors. Here is a basic explanation of this behavior for metals; While very true these factors are very...
  20. AlanD

    Properties of metals at Cryo temp

    It basically comes back to crystal structure. In steels there is a low temperature brittle phase (martensite) which forms from the austenite. In some steel groups, the austenite is converted to another phase structure, that prevents marteniste forming, so the are not susceptible to a ductile -...

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