4 ms·

I'm talking about the frame and the body panels. Those aren't normally user serviceable parts. If there are other parts (suspension, etc) that are steel I would

by feld 10y ago

I'm talking about the frame and the body panels. Those aren't normally user serviceable parts. If there are other parts (suspension, etc) that are steel I would expect they need to be replaced for regular wear long before they completely rust through. If the Model 3 isn't an aluminum body and frame I no longer want one. I live where it snows and they salt a lot. I want some level of confidence the car won't be completely trashed in a few short years. That forum thread is certainly interesting....

dsfyu404ed 10y ago
sacrificial coating > good paint > good anodes> base metal. (I'm ignoring fancy expensive things such as high quality stainless and titanium alloys because you can't build a million car bodies out of those) Properly coated steel will last longer than poorly coated aluminum. Just look at galvanized or properly painted steel vs an aluminum outboard that lost it's anode (saltwater applications of course). Aluminum "doesn't corrode" because the initial corrosion forms a coating that prevents further corrosion. If you wire wheel AL bar stock it will shine. If you put that bar stock outside somewhere other than the desert it will tarnish in a few days. If you put that bar stock underneath a vehicle it will slowly turn to dust as the dust/dirt/etc slowly blast away any surface coating that forms exposing new material which corrodes and the cycle is repeated until your aluminum part has turned to dust. In reality something as thick as a control arm will fatigue and crack long before that. If you're trying to reduce weight by using aluminum there's a near 0% chance that you're designing the part to last more than a few hundred percent of the warranty period for the most demanding typical use case (in the case of suspension parts that would be something like doing 10k mi/yr on graded dirt and potholed pavement) Among the google results for "why aluminum doesn't rust": http://news.stanford.edu/pr/00/aluminum511.html http://news.stanford.edu/pr/00/aluminum511.html
tropo 10y ago
Aluminum is pretty terrible with salt. Chloride disrupts the surface layer. Cool experiment to prove it: put copper sulfate (bright blue root killer crystals, available in the plumbing section of a hardware store) in water until you get a blue solution. Add aluminum foil. Observe that there is no reaction. Add chloride (table salt or hydrochloric acid) and watch the reaction start. (you get copper powder)

by feld 10y ago

dsfyu404ed 10y ago

sacrificial coating > good paint > good anodes> base metal. (I'm ignoring fancy expensive things such as high quality stainless and titanium alloys because you can't build a million car bodies out of those) Properly coated steel will last longer than poorly coated aluminum. Just look at galvanized or properly painted steel vs an aluminum outboard that lost it's anode (saltwater applications of course). Aluminum "doesn't corrode" because the initial corrosion forms a coating that prevents further corrosion. If you wire wheel AL bar stock it will shine. If you put that bar stock outside somewhere other than the desert it will tarnish in a few days. If you put that bar stock underneath a vehicle it will slowly turn to dust as the dust/dirt/etc slowly blast away any surface coating that forms exposing new material which corrodes and the cycle is repeated until your aluminum part has turned to dust. In reality something as thick as a control arm will fatigue and crack long before that. If you're trying to reduce weight by using aluminum there's a near 0% chance that you're designing the part to last more than a few hundred percent of the warranty period for the most demanding typical use case (in the case of suspension parts that would be something like doing 10k mi/yr on graded dirt and potholed pavement) Among the google results for "why aluminum doesn't rust": http://news.stanford.edu/pr/00/aluminum511.html http://news.stanford.edu/pr/00/aluminum511.html

tropo 10y ago

Aluminum is pretty terrible with salt. Chloride disrupts the surface layer. Cool experiment to prove it: put copper sulfate (bright blue root killer crystals, available in the plumbing section of a hardware store) in water until you get a blue solution. Add aluminum foil. Observe that there is no reaction. Add chloride (table salt or hydrochloric acid) and watch the reaction start. (you get copper powder)