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  #1  
Old 03-11-2021, 06:43 PM
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galderdi galderdi is offline
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Default Joining different grades of aluminium?

Joining different grades of aluminium?

I am at the start of my project to build an Aluminium Spyder. I need to keep the total weight way down. This is essential to ensure I can get it registered. If I go over the target weight (550kg) I will be forced to pay for additional engineering tests which will cost thousands.

So I am choosing my materials carefully. There are certain panels which are structural. These will need to remain 2mm aluminium as per the design.

There are other chassis panels (not body panels) which are not structural. I plan to reduce these from the 1.4mm as per the design to 1mm.

The body panels will largely be 1mm in order to save weight. But I am a little concerned about the average Joe who wonders up while I have my head turned and proceeds to put a dent in the panel.

I have a couple of questions for those more experienced than I:

1.I have had a play with 1mm and once shaped it seems fairly resistant to minor/unintentional dents. Is that the general experience out there?

2. There are only a couple of areas likely to take this type of dent (Across the top of each guard / fender (Front and rear) and across the top of the doors. Would there be any issues if I used 1mm for most of a panel but welded in a thicker grade in the higher risk areas?

Any other thoughts or suggestions?
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  #2  
Old 03-11-2021, 08:26 PM
steve.murphy steve.murphy is offline
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Hi Greg,
Welcome to AMS. I am from the northern side of Brisbane.
I think you might run into problems with this idea, but I am no expert so take if for what it’s worth. Perhaps you could reinforce these soft areas somehow from the bottom side with something you can add after the weigh in if you know what I mean.
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  #3  
Old 03-12-2021, 01:14 AM
Jaroslav Jaroslav is offline
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We used Al 1.2mm. for MB hood. The plate was semi-hard. You can bend the joints 90 degrees in some places and weld at the edges. Reinforcement is created.
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Old 03-12-2021, 07:26 AM
Marc Bourget Marc Bourget is offline
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I'd also suggest you gain information on the properties on alloys and grades of aluminum.


I understand your interest in a quick answer, but your path may be easier as a result of that knowledge.
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Old 03-12-2021, 10:22 AM
crystallographic crystallographic is offline
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Quote:
Originally Posted by galderdi View Post
Joining different grades of aluminium?

I am at the start of my project to build an Aluminium Spyder. I need to keep the total weight way down. This is essential to ensure I can get it registered. If I go over the target weight (550kg) I will be forced to pay for additional engineering tests which will cost thousands.

So I am choosing my materials carefully. There are certain panels which are structural. These will need to remain 2mm aluminium as per the design.

There are other chassis panels (not body panels) which are not structural. I plan to reduce these from the 1.4mm as per the design to 1mm.

The body panels will largely be 1mm in order to save weight. But I am a little concerned about the average Joe who wonders up while I have my head turned and proceeds to put a dent in the panel.

I have a couple of questions for those more experienced than I:

1.I have had a play with 1mm and once shaped it seems fairly resistant to minor/unintentional dents. Is that the general experience out there?

2. There are only a couple of areas likely to take this type of dent (Across the top of each guard / fender (Front and rear) and across the top of the doors. Would there be any issues if I used 1mm for most of a panel but welded in a thicker grade in the higher risk areas?

Any other thoughts or suggestions?

Minor considerations:

(Having restored a few dozen old "significant" race cars)


Typical thickness (race, not sport) of "majors" = 1mm
Cobra = 1.25mm
Rebodied for street/sport = 1.5mm
alloy = 3003/3005 - most mfrs (23-25ksi tensile)

5052/"Birmabright" = Aston door skins, Porsche 904 tanks (45-50ksi tensile)
6061 tensile = 5052 tensile, in = thickness, but 6061 is heat treatable.
-end-
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Old 03-12-2021, 11:22 AM
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heinke heinke is offline
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On my Ferrari 250 GTO tribute, I used 5052 in .063 thickness on the door and trunk skins for the better dent resistance. I could do this as those skins had very little shape in them. I did have to anneal the edges twice during the skin installation just to turn the outside hem over the mounting flanges. 5052 work hardens very fast and in that condition can be hard to work. For body work with shape, I use 3003 as 5052 work hardens too fast and thus is not very easy to shrink/stretch to add in shape.

On the Miura, I've used 5052 in .063 for the door jambs and door frames. I did this instead of 3003 as they need to be rigid as possible or I'll have wind whistles from air leaks. Some of these areas have some complex weather strip grooves in them. I've been annealing the sheet and using hammer forms for those areas will good results. I used .050 3003 for the front fender liners (lots of shape). I plan to use .063 3003 for all the body panels. There is some door jamb areas where the 5052 and 3003 will meet up and I'll be welding the two different alloys together. The two different alloys will be the same sheet thickness though. I haven't done that yet so I can't comment on challenges yet.

For non-structural panels that aren't part of exterior body work, I tend to use .040 and .050 depending on their size and function. For example, foot box sides and top, get the thinner sheet. Interior panels like a door card that might get pushed or pulled for door operation would get the thicker.

I would avoid using two different sheet thicknesses in a butt weld joint that needs a good surface finish. Removing the weld shrink and planishing the surface would be overly complicated by the different thicknesses. My rule of thumb is "keep it simple as possible". There's enough complicating factors to consider in metal shaping so I try to avoid knowingly introducing additional ones.
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Old 03-12-2021, 05:18 PM
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galderdi galderdi is offline
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Thanks everyone,

This all makes sense. I'll stick to the same material for each panel.
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  #8  
Old 03-12-2021, 06:45 PM
crystallographic crystallographic is offline
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Quote:
Originally Posted by heinke View Post
On my Ferrari 250 GTO tribute, I used 5052 in .063 thickness on the door and trunk skins for the better dent resistance. I could do this as those skins had very little shape in them. I did have to anneal the edges twice during the skin installation just to turn the outside hem over the mounting flanges. 5052 work hardens very fast and in that condition can be hard to work. For body work with shape, I use 3003 as 5052 work hardens too fast and thus is not very easy to shrink/stretch to add in shape.

On the Miura, I've used 5052 in .063 for the door jambs and door frames. I did this instead of 3003 as they need to be rigid as possible or I'll have wind whistles from air leaks. Some of these areas have some complex weather strip grooves in them. I've been annealing the sheet and using hammer forms for those areas will good results. I used .050 3003 for the front fender liners (lots of shape). I plan to use .063 3003 for all the body panels. There is some door jamb areas where the 5052 and 3003 will meet up and I'll be welding the two different alloys together. The two different alloys will be the same sheet thickness though. I haven't done that yet so I can't comment on challenges yet.

For non-structural panels that aren't part of exterior body work, I tend to use .040 and .050 depending on their size and function. For example, foot box sides and top, get the thinner sheet. Interior panels like a door card that might get pushed or pulled for door operation would get the thicker.

I would avoid using two different sheet thicknesses in a butt weld joint that needs a good surface finish. Removing the weld shrink and planishing the surface would be overly complicated by the different thicknesses. My rule of thumb is "keep it simple as possible". There's enough complicating factors to consider in metal shaping so I try to avoid knowingly introducing additional ones.

Joel,
This is very good practical info for car builders.

I might add a couple hints for faster easier results:
(from my own experience - not theory, not "heard someplace" ...)

6061 = pretty close to 5052 for strength, cold.

(6061 used for Tesla bodies, and for Ford truck bodies.)

However, 6061 can be worked hot, 5052 NOT.
6061 work hardens more slowly, so you go 3x farther before annealing.
6061 anodizes well.

5052 has greatest corrosion resistance in the aluminum alloy family, and that coupled with its high strength make it ideal for chassis, electronics, medical, and marine applications.

Both are weldable - 5356 filler.

Both can be welded to 1100, 3003, and to each other - use 5356 filler.

IMPORTANT: *** Joel's note about "butt-welding dissimilar thicknesses" being a headache*** TAKE NOTE.

-end-
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Last edited by crystallographic; 03-12-2021 at 06:48 PM.
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  #9  
Old 03-13-2021, 01:02 PM
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galderdi galderdi is offline
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Thanks everyone. This is great information. Is it normal to have trouble finding a supplier for the various grades?
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  #10  
Old 03-13-2021, 06:41 PM
crystallographic crystallographic is offline
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Originally Posted by galderdi View Post
thanks everyone. This is great information. Is it normal to have trouble finding a supplier for the various grades?

....in oz.....
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