As a practical matter, I don't know what testing they're doing. As the system is set up, none is necessary. The scrapping, like the production itself, is set up along "zero defects" principles.
I think my last post left some important things unsaid, so let me complicate it further.
If Ford were to spec their sheet aluminum by AA grade, it would require 6 grades but 11 scrap streams. That's because, say, 6061 from Alcoa is not 6061 from Novalis. If they're required to toll the scrap back to the original AA designation, Alcoa won't accept Novalis scrap, and vice-versa. This has to do with the way each company handles the secondary ingredients in the alloys.
My alloy example may not be one that actually causes trouble; it may be other alloys. But that's the principle.
You probably have heard that high-volume auto-body stamping of aluminum is a real headache because of inconsistencies in the aluminum properties. The above situation is a major source of that problem.
So Ford set up their own system based on performance, with some allowance for secondary chemistry but with other tight controls, especially temper. This allows them to stamp one of their four grades with greater consistency -- which means, for the most part, consistent springback.
The root and source of most "transportation grade" aluminum alloys is the aerospace industry, as it always has been. They have different requirements than automotive applications. So the old system of AA grades does not work well for the car industry.
The remelt is done at their casting facility
And controlled fusion will be practical. Wind power for everyone, too, so we'll have a choice. Or we'll be transitioned to the "hydrogen economy" (with molecular hydrogen appearing magically, because of course it doesn't have to be _made_ from _water_ using way more energy than you get out of it later).
And we won't be buying cars from the major manufacturers any more, because they'll be 3D printed locally from 100% recycled aluminum cans and plastic soda bottles.
Damn, but it's a good thing I'm never cynical nor sarcastic!
Did you get a handle on what percentage of a sheet becomes scrap? It would be interesting (from a musing standpoint, if not a metallurgical or economi c one) to know how many times a given piece of aluminum has been through th e punch/scrap/remelt process before it actually becomes part of a truck.
Well, there's their tradeoff: a slight disadvantage in machining (possibly; but not necessarily, surface finish may be harder to achieve) for a savings in the complexity of re-melting the scrap. With a high value-added product like a Rotax engine, it sounds like the logical way to go.
Ford is using stamping lubricant and it's worth it to go through the scrap cleaning step.
It appears the WSJ is right. Every major Western and Japanese manufacturer is in the process of developing, or is nearly ready to produce, high-aluminum-content cars. Ford is looking into what they can do with magnesium.
In the very short run, there appears to be a lot of development space left for advanced high-strength steels. (AHSS). And the more sophisticated vehicles are using a fair amount of boron steel in hot-stamping, which achieves over 200,000 psi yield. Door pillars and crush areas are major applications for hot-stamped steel.
Not yet. I'll be spending more time with them to find out things like that.
If grain direction doesn't matter, a yield of 70% from a sheet is pretty reasonable. If grain direction does matter, it will be somewhat lower, depending on how the parts nest on the sheet.
The Audi A8 has been around for a couple of decades now. I wonder how the older ones fair these days and if they suffer from any problems with the use of aluminium structurally.
A lot of the F-150's I see on the road aren't hauling anything in the bed. But I wonder how they'll hold up for lawn service, plumbers, farmers, etc. with a lot of stuff banging around in the back all the time. I'm not a pickup or Ford guy, so don't really care that much. Time will tell.
I don't know. But, without them saying anything negative about it, it was clear that the engineers at that conference consider the A8 to be a "first generation" effort with aluminum, not practical for a high-production car.
Look at all the dump trucks hauling gravel. LArge percentage are aluminum boxes, and they stand up better than most steel boxes.
6061T6 or T653 is pretty tough stuff - and there are tougher alloya apparently.
Remember that the stiffness and strength of a panel varies with the
*cube* of its thickness. An aluminum panel as strong as a steel panel will still be much lighter than the steel panel. You can make the aluminum panel a great deal stronger than the steel panel, and it is still a lot lighter.That's the whole principle behind replacing steel with aluminum. It's not only lighter; it's also stiffer and stronger, in terms of plate stiffness and strength. (Not to complicate this point, but the tensile and compression strengths of aluminum alloys are nearly identical to those of steel panels of equivalent weight. But we're talking here about denting or bending a panel, which is where the cube rule applies.)
Where it can get complicated is in things like dent resistance. This can be a complex resolution of forces. When the aluminum panel is a lot stiffer, that also means that the area surrounding a dent is putting up a lot more resistance to being bent. So, instead of oilcanning and bouncing back, as a thin steel panel might do, the same blow to aluminum might cause a dent, because the surrounding aluminum is resisting oilcanning and that can allow a concentration of the denting force in one local spot.
A little thought about this makes it clear that you can't generalize about the dent resistance of aluminum. It depends a lot on the shape of the panel. That steel panel might resist oilcanning because it has a curved shape; it might, therefore, dent more easily than an aluminum panel. A completely flat steel panel, in contrast, might just spring away, or "oilcan," when the same force is applied. But you'll notice that there is more crowning of panels in vehicles today, which is done to improve stiffness as high-strength steel panels keep getting thinner. That's how they save weight with the high-strength steels used in car bodies today. They have to recover the lost stiffness by crowning and reinforcing the steel.
An aluminum truck can be stronger, stiffer, and lighter than a steel one. But its ability to resist dents and dings depends on the panel shape -- in particular, how much it is curved, or crowned.
Its good that you wonder that. I am no car person, believe me. I don't kn ow about their aluminum use before 2015. But, I keep hearing that Toyotas are the ones that have rarely needed any kind of repair on average. I don' t think Volkswagon and Audi are known for that reputation.
Also, SUV's of many types rarely need repair, too. "though I hate defending SUV's).
My big worry with aluminum and such alloys is fatigue resistance. All the aluminum products I've had fail did so because a boss or weld or the like fatigued and broke free. Typically not economically repairable, although in a car the economics will differ.
Joe Gwinn
That's true for aircraft. Fatigue is much less of a problem for automobiles. Weld failures on highly stressed parts are a big problem with aluminum, but the car makers aren't using much welding, except in combination with adhesive bonding (weld-bonding).
Joining and assembly are perhaps half of the story about different manufacturing methods for the aluminum-bodied cars.
I would think it is a 5xxx series alloy. It is work hardening and corrosion resistant. The more it is abused the stronger it gets. Boats are typically made from it for that reason. Salt hauling trailers are also made from it. If it is made from 6061 there will be corrosion complaints.
Now, I hate aluminum wire (versus copper wire) because of the increased fire factor.
I remember reading somewhere that "Aluminum fires are more tenacious", but compared to what, I don't know. I imagine the stuff can't be any safer than the steel that was used in car manufacturing back in the 1950's.
We're talking mostly about crash repairs, which know no brands.
Ford is using both 5xxx and 6xxx grade equivalents in the body and structure of the F-150. There's some 7075 in there, too.
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