There are a lot of differences between numbers and real life like you mention Dave. another is steel has to be bigger because of rust over it's life.
A similar thing happens with CF and medium tech composites where CF looks much stronger but ends up only 5-10% lighter once in place.
In looking for lightweight rims for my lightweight EV's because unspunng weigh ratios are much worse than a heavier car, I measured about 15 each of alum and steel and was surprised to find both were about equal in weight average.My biggest problem so far has been keeping unsprung weight down at a reasonable cost.
for trcks this lighter weight will pay for itself in either better mileage or higher loads/thus profit so unless too much more costly the Alum is the way to go. The only downside is the rims get damaged more esily in potholes, etc and maybe getting the tires changed problems.
The nice forged aluminum wheels may certainly offer a good weight reduction, which will reduce fuel consumption, and so from that point it will be a benefit to all. BUT there is a tradoff to be reconed with, which is corrosion. Here in Micchigan where there are many tons of salt dumped on every roadway each winter, I have experienced rim leaks with my aluminum wheels, on every car. Not a tragedy, but certainly an inconvenience, since they must either be repaired, or air added to the tire frequently. I never had that problem with steel wheels. Another challenge is damage to the wheels, I have seen broken aluminum wheels, which must be replaced, while I have hammered bent st=eel wheels back into shape right on the vehicle. Hammering is much faster and cheaper than replacing.
My point being that it is not a one-sided contest.
My question is how can corrosion of aluminum wheels from concentrated salt water exposure be prevented? Is there a method that is demonstrated to work?
Dave, thanks for the feedback. I agree about the greenwashing/PR angle of many corporate sustainability programs. However, it seems to me that doing LCAs is better than not doing them, and having such programs is better than not even paying attention to the subject. The better, more complete LCAs and actually results-producing programs stand out from the crowd. And some actual good can be done along with the PR when the LCA results are used. This is the case in many human endeavors, especially those that require big changes, so I say don't throw the baby out, too.
William, funny you should ask that question. I just filed an article--it should publish soon--on a new non-toxic substance for preventing salt corrosion on wrought aluminum–zinc–magnesium–copper AA7000 alloys commonly used in aerospace and automotive apps. Inorganic and organic corrosion inhibitors already exist, but they tend to be either toxic or potentially toxic. Stay tuned.
@Ann: Looking forward to seeing your new article. Replacing chromate conversion coatings with less environmentally-harmful alternatives is a topic that is very important to me.
We are currently transitioning from a traditional chromate to Alodine EC² to protect aluminum die castings from corrosion. It's a great coating, but, like everything, it has some limitations. One of the biggest is that, since it's an electrodeposited coating, it's very difficult to coat internal passages.
I've often thought that an LCA comparing the environmental impacts of chromate vs. EC² would be interesting. Chromating creates a hazardous waste stream -- but the large amounts of electricity required to apply electrodeposited coatings like EC² don't come without environmental costs, either. It would be interesting to see how they balance out.
(By the way, now that you mention it, Alcoa's LCA for the aluminum wheels doesn't include the environmental impacts of the chromating process, either).
Mydesign, I'm not sure I understand your question. There was no discussion of changing either the number of wheels or trailer dimensions. The point of the aluminum vs steel wheels, as we state in the article, is that they both weigh less and are strong enough to support tires that can bear heavier loads. This is all part of CAFE-type regulations for commercial vehicles for lowering carbon emissions. Does that answer your question?
Ann, my guess is that any coating at all will add to the cost and therefore not be added tp OEM wheels on passenger cars. But some fancy appearance treatment would probably be added if it was not too expensive. I have not seen any originally applied coating on Chrysler product aluminum rims since they have been making them, which is quite a few years. It seems that the management does not accept that corrosion exists. Of course, for Chrysler upper management, vehicle problems don't exist. Cars serviced daily seldom suffer problems.
I tend to think that quality consists of remaining able to meet the service specifications of a product, while it seems that to many others quality equates to the number of features. "What we have here is a failure to commu8nicate", it seems. Unfortunately the marketing wonks all seem to follow those who seek features, regardless of how useless they are.
So it sounds like the available coatings are not being applied by automotive OEMs. Considering how long the salt problem has been going on, and how well publicized it's been, you'da thunk by now it would be common--and cheaper.
Ann, for many years steel wheels were painted inside and outside because that was the cheapest possible way to make them look good for a while. They would rust when the paint was scratched off, but there were very seldom any leaks due to corrosion.
Today I had to take the new tire on it's rim back to Belle Tire as it had gone flat overnight. The problem was that they had not properly cleaned and sealed the rim on the aluminum wheel. So the problem is alive and well today.
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