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Steel frame and Aluminum body panels?

Discussion in 'Model 3' started by ChooseGreen, May 16, 2016.

  1. ChooseGreen

    ChooseGreen Member

    Apr 6, 2016
    Ontario, Canada
    There is a lot of speculation out there that the Model 3 will have a steel frame and aluminum body panels. The below questions make that assumption.

    Are there any metallurgical experts out there? A LOT of road salt is used around my parts so I love the idea of aluminum body panels. If I could afford even a CPO Model S, I would be heading that direction due to the aluminum body. Cars older than 12 or so years generally look like rust buckets here and nicer cars often hibernate in winter until the salt is washed away by spring rains (I do that with my bicycles).

    I am under the impression that joining steel and aluminum components must be done in a specific way so as to not exacerbate corrosion, but is this something that is fairly easy and cost-effective to work around?

    Additionally, what sort of rust protection could/should be done to a aluminum body, steel structure Model 3 such that it will continue to be safe and in one piece 20 salty years after delivery?

    Thanks for your input!
  2. JeffK

    JeffK Well-Known Member

    Apr 27, 2016
    Depends if it was joined correctly or not... Tesla has a history of not doing this correctly leading to galvanic corrosion. You'd need electrical isolation between the metals.

    Assuming everything is joined correctly just make sure you protect the paint and wash the salt off the car in the winter.
  3. Face_Disguise

    Face_Disguise Member

    Aug 24, 2014
    Some of the drivers at the Model 3 reveal event were stating that the body is a mix of steel and aluminium, with the majority being steel. I would be surprised and delighted if the whole body ended up being aluminium at this point....
  4. Zaphod

    Zaphod Galaxy President (former)

    Dec 10, 2015
    Austin, TX
    Yes, joining of two dissimilar materials can be tricky and need to prevent what is called "galvanic corrosion". I won't go into all the science mumbo-jumbo, but you can search for that and learn about it to your hearts content. Structural adhesive is usually the best way to join these materials because not only is it strong, it keeps the joint air and water tight (if done correctly :D) and keeps the materials from touching each other.

    Keep in mind, aluminum is not impervious to salt either. Not sure about in Canada, but a lot of northern US states are applying liquid deicers such as magnesium chloride as well as others. These really do a number on anything that is unprotected, steel, aluminum or anything else susceptible.

    Most, if not all, cars produced today really don't have frames any more, everything is essentially a uni-body type construction although one could argue that the skateboard/battery pack/running gear could be consider a "frame" since it is a structural member that the body attaches to.

    Corrosion protection and coating technologies are greatly improved from a decade ago, so I wouldn't expect corrosion issues, if things are done correctly. It is really rare to see modern cars that have rust issues, unless they are horribly taken care of.

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