The OFFICIAL Steel vs. Aluminum Fact-Checking Thread
10-19-2016, 10:35 PM
#31
Hopefully this non technical overview can help people envision what GM did.
I have worked on a B-17 which is all aluminum. Aluminum stringers tied to aluminum formers, sheeted with aluminum skins, all riveted together with aluminum rivets. Individually the parts are flimsy and can be easily bent or broken, but once assembled becomes a very strong structure, and highly dent resistant. The skin on a B-17 is extremely thin, most of it is the thickness of a business card or less, and a sharp edged object like a tool box corner would go right through it, but drop a bunch of heavy ball bearings on it and they will bounce right off.
GM knows this and that is exactly what they did in that commercial. Notice that the steel bed was also full of dents, but no holes due to the sharp corner. With rocks and stones dropped in both beds, both will dent, but the aluminum can have fewer dents due to its elasticity. Hardened aluminum alloy tends to have more spring to it, but once it is exceeded, it dents, and those dents don't come out without fracturing the metal. Steel dents easily but remains flexible, you can massage that same dent out. It is also more resistant to sharp impacts since it doesn't fracture, and that is how GM came up with their commercial. I would not be surprised if they didn't drop the box several times on the same spot to weaken the aluminum before taking that final shot.
The downside of aluminum though, once you distort its shape, you can't return it without first heat treating to soften it, then heat treat it again to return its strength after being reshaped. The hood of my 14 was bent from hitting a deer. The body shop could not straighten the lip above the grill, it would not retain its shape.
On the B-17 we had to fabricate all new bulkheads out of soft aluminum, which are pressed over dies to form their shape, then they are heat treated, which causes warping, so they have to be pressed a second time in order to straighten them and set the shape, but you have a very short window in order to do this before the molecules fully align. The difference between the soft and fully treated aluminum is substantial. The before part you could fold it into a ball, but once treated you could not bend it, it would flex, but not bend at all. You can't form it fully hardened, it would crack.
One thing I found by watching how its made, is that when assembling metal bodied cars, they use an adhesive between parts, and then rivet them together. They do this between steel and aluminum parts as well as aluminum to aluminum, so that could be one way they combat bi-metal corrosion.
I have worked on a B-17 which is all aluminum. Aluminum stringers tied to aluminum formers, sheeted with aluminum skins, all riveted together with aluminum rivets. Individually the parts are flimsy and can be easily bent or broken, but once assembled becomes a very strong structure, and highly dent resistant. The skin on a B-17 is extremely thin, most of it is the thickness of a business card or less, and a sharp edged object like a tool box corner would go right through it, but drop a bunch of heavy ball bearings on it and they will bounce right off.
GM knows this and that is exactly what they did in that commercial. Notice that the steel bed was also full of dents, but no holes due to the sharp corner. With rocks and stones dropped in both beds, both will dent, but the aluminum can have fewer dents due to its elasticity. Hardened aluminum alloy tends to have more spring to it, but once it is exceeded, it dents, and those dents don't come out without fracturing the metal. Steel dents easily but remains flexible, you can massage that same dent out. It is also more resistant to sharp impacts since it doesn't fracture, and that is how GM came up with their commercial. I would not be surprised if they didn't drop the box several times on the same spot to weaken the aluminum before taking that final shot.
The downside of aluminum though, once you distort its shape, you can't return it without first heat treating to soften it, then heat treat it again to return its strength after being reshaped. The hood of my 14 was bent from hitting a deer. The body shop could not straighten the lip above the grill, it would not retain its shape.
On the B-17 we had to fabricate all new bulkheads out of soft aluminum, which are pressed over dies to form their shape, then they are heat treated, which causes warping, so they have to be pressed a second time in order to straighten them and set the shape, but you have a very short window in order to do this before the molecules fully align. The difference between the soft and fully treated aluminum is substantial. The before part you could fold it into a ball, but once treated you could not bend it, it would flex, but not bend at all. You can't form it fully hardened, it would crack.
One thing I found by watching how its made, is that when assembling metal bodied cars, they use an adhesive between parts, and then rivet them together. They do this between steel and aluminum parts as well as aluminum to aluminum, so that could be one way they combat bi-metal corrosion.
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10-27-2016, 07:05 PM
#32
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Good info here in this thread! I have pondered the question of corrosion resistance with the aluminum body and how that might compare to steel panels in the long term. Would there be a better process for corrosion protection than conventional rust-proofing? As mentioned above the dissimilar metal corrosion if using aluminum panels and steel fasteners could be a point of concern for later years repairs and maintenance. Do you know what the grade of aluminum is used?
10-28-2016, 10:22 AM
#33
Why Military Grade of course! Everyone should know that if they have seen the commercials!
Actually its 6000 series aluminum alloy, which includes Magnesium and silicon. It is heat treated after forming to harden it. Its pretty much the same alloy used in fighter jets and armored equipment.
Actually its 6000 series aluminum alloy, which includes Magnesium and silicon. It is heat treated after forming to harden it. Its pretty much the same alloy used in fighter jets and armored equipment.
10-31-2016, 02:14 PM
#34
Good info here in this thread! I have pondered the question of corrosion resistance with the aluminum body and how that might compare to steel panels in the long term. Would there be a better process for corrosion protection than conventional rust-proofing? As mentioned above the dissimilar metal corrosion if using aluminum panels and steel fasteners could be a point of concern for later years repairs and maintenance. Do you know what the grade of aluminum is used?
And yes, like acdii said, 6000 series. My guess is 6061 as that's pretty common but I don't know that for sure. It really is much tougher, I think soda cans for example are in the 3000 series.
10-31-2016, 02:40 PM
#35
Senior Member
When motorcycle race teams were experimenting with aluminum frames, they ran into some issues. When designed similar to the steel counterparts, they were super light but suffered flexing. That flexing was not a problem until they realized AL can't flex long before it cracks. So they designed frames super ridged in the early 80's but found that a ridged frame handles like crap. Fast forward to the present and they have strong AL frames with flex built into them but are still durable.
10-31-2016, 02:51 PM
#36
Senior Member
One AL series that is starting to be widely used more is the 5000 series. It has magnesium in it and generally is more corrosion resistant. Many times auto panels are made from 6111 AL and some aircraft have 7000 series AL.
11-01-2016, 10:35 AM
#37
Heat treatable
6xxx Series
The 6xxx series are versatile, heat treatable, highly formable, weldable and have moderately high strength coupled with excellent corrosion resistance. Alloys in this series contain silicon and magnesium in order to form magnesium silicide within the alloy. Extrusion products from the 6xxx series are the first choice for architectural and structural applications. Alloy 6061 is the most widely used alloy in this series and is often used in truck and marine frames. Additionally, the iPhone 6 extrusion was made from 6xxx series alloy.
Not heat treatable
5xxx Series
Magnesium is the primary alloying agent in the 5xxx series and is one of the most effective and widely used alloying elements for aluminum. Alloys in this series possess moderate to high strength characteristics, as well as good weldablility and resistance to corrosion in the marine environment. Because of this, aluminum-magnesium alloys are widely used in building and construction, storage tanks, pressure vessels and marine applications. Examples of common alloy applications include: 5052 in electronics, 5083 in marine applications, anodized 5005 sheet for architectural applications and 5182 makes the aluminum beverage can lid. The U.S. military’s Bradley Fighting Vehicle is made with 5083 and the 7xxx series aluminum.
When used as sheets with minimal stamping or bending, most likely they would use 5xxx series, but where there are compound stampings, such as door frames and other areas with multiple curves, they would most likely use 6xxx series. Usually its stamped and then treated to prevent cracking and to realign the molecules after bending. That can only be done with the 6xxx series though.
Would be interesting to see how Ford does it.
11-07-2016, 06:56 PM
#38
Your Mod Superstore!
Fantastic info here, guys! This is the kind of thing that makes this community stand out.
11-19-2016, 04:31 PM
#40
Crotchety Old Man
This has been an excellent read.
I have been waiting to see if any issues pop up in the 15+ due to the action of dissimilar metals, mostly to see where Ford design or production issues left spots where proper insulating is not taking place. All ready have seen guys put steel screws to mount mud flaps etc and corrosion start on the new trucks.
As mentioned, there are pros and cons to using aluminum vs steel, and also as mentioned, many vehicles use some aluminum panels already. I recall ford E series vans having fiberglass panels in some cases too.
And the commercial where they drop rocks on the bed... I get bothered when I see steel bed pick ups without a bed liner and they are all rusted and scratched and dented. Put a plastic liner in at least.
I Imagine if the bed becomes an issue, they can raise the price of the truck a bit and include spray on bed liner or drop in liner.
I too am interested in long term value of the new F series, as well as insurance costs. If specific equipment is required to replace and repair panels, repair costs will be higher, and it could drive up insurance rates compared to steel paneled trucks.
Thanks for everything Mr Meeseeks
I have been waiting to see if any issues pop up in the 15+ due to the action of dissimilar metals, mostly to see where Ford design or production issues left spots where proper insulating is not taking place. All ready have seen guys put steel screws to mount mud flaps etc and corrosion start on the new trucks.
As mentioned, there are pros and cons to using aluminum vs steel, and also as mentioned, many vehicles use some aluminum panels already. I recall ford E series vans having fiberglass panels in some cases too.
And the commercial where they drop rocks on the bed... I get bothered when I see steel bed pick ups without a bed liner and they are all rusted and scratched and dented. Put a plastic liner in at least.
I Imagine if the bed becomes an issue, they can raise the price of the truck a bit and include spray on bed liner or drop in liner.
I too am interested in long term value of the new F series, as well as insurance costs. If specific equipment is required to replace and repair panels, repair costs will be higher, and it could drive up insurance rates compared to steel paneled trucks.
Thanks for everything Mr Meeseeks