Metallurgy Saves Weight


#1

This article from USA Today and I assume the Detroit Free Press discusses GMs new process for welding aluminum to steel. If it works in a mass scale, GM could save aa whole lot of weight on new cars. The article goes on to say that GM is saving a few hundred pounds per vehicle; almost 10%, even without the new welding technique. In addition to weight savings, factory conversions can be done much faster than if they went to an all aluminum body as Ford did. Whatcha think? I’m excited because metallurgy saves the day again!


#2

How is galvanic corrosion avoided?


#3

Good question ,but it can be minimized. Wish they would start making more grills and such out of aluminum again,plastic is a bit over used IMO.
Plastic is best used for battery trays ,fender liners an things like that. Lets hear it for Metallurgy !


#4

Interesting.
I think I’d avoid buying one of these Caddys for at least a decade or two. I have vivid memories of the how well GM’s new technologies worked (not) on my '72 Vega. And on my '95 Saturn.


#5

How much does weight really affect gas mileage? I mean you have a 250 lb passenger, now I drop 2mpg? just asking.


#6

You make a good point, barky, but constantly tightening federal regulations are forcing manufacturers to spend billions that could have been spent on real technological advancements on trying to squeeze every miniscule fraction of a mpg that they can out of every car design.

Regulatory compliance is “job one”.


#7

Some years ago ‘Scientific American’ published an article about automobile metallurgy by GM’s chief metallurgist. They had a different kind of steel for every part. I remember his comment ‘There’s no mild steel in a car anymore.’

When McNamara took over Ford he was horrified by the death toll in traffic. He pushed for seat belts and other safety measures. A member of the board complained that while he was selling safety, GM was selling cars. Federal regulation forced manufacturers to make cars safer and more efficient, and it isn’t all that expensive. Left to their own devices American manufacturers make what we want: bigger, shinier, faster, louder… to hell with safety, clean air, people’s ears. I was in southern California in the 50s when motorcycle messengers wore gas masks and you couldn’t see more than a few blocks. Even in the '70s in Pasadena I remember smog obscuring the next-door San Gabriel mountains.


#8

Remember horizon to horizon stars at the cabins as a kid, now probably a 15 degree fuzz before the constellations are visible. Car or whatever pollution for sure.


#9

Maybe they are messing with the alloys or something. I’ve never had any luck with aluminum. Just melts too fast. I would have thought maybe crimping and gluing like door panels would be a better course of action but I’m no engineer. I’m just trying to envision a spot weld with aluminum and steel.

Yeah I probably carry an extra hundred pounds in the trunk now with all my junk. Plus that trailer hitch I put on was not light either. I had to use a jack to hold it in place to get it bolted up. But then I’m a weakling, but still it’s gotta weigh 40 pounds.


#10

Personally I don’t see much of a fuel economy difference between a car that weighs say 3400 pounds and one that weighs 3100.

I’m a real stickler for monitoring fuel mileage on my Lincoln and have never been able to detect over 16 years one iota of difference on road trips no matter if I was traveling alone with almost no gear or with passengers and the trunk stuffed to the taillights.


#11

Depends on how much throttle you have to use to get the thing to move,one reason the base engines dont do much better on fuel economy,if you have to move too much mass a small engine will consume about as much fuel trying to keep up,(found that out in my Dodge )


#12
Barkydog Remember horizon to horizon stars at the cabins as a kid, now probably a 15 degree fuzz before the constellations are visible. Car or whatever pollution for sure.

Probably light pollution. The air is likely cleaner today than it was in the '60s, but there are so many outdoor lights in major cities that it competes with star light.
I recall a night time hike at the Sipapu ski resort in northern New Mexico, the weather conditions gave us crystal clear dry air and the milky way was simply amazing once my eyes got acclimated to the darkness.


#13
When McNamara took over Ford he was horrified by the death toll in traffic. He pushed for seat belts and other safety measures. A member of the board complained that while he was selling safety, GM was selling cars. Federal regulation forced manufacturers to make cars safer and more efficient, and it isn't all that expensive. Left to their own devices American manufacturers make what we want: bigger, shinier, faster, louder... to hell with safety, clean air, people's ears.

The automakers then found that safety could be used to sell huge gas guzzling cars and today most cars exceed the minimum safety standards due to consumer demand. Safety is advertised in the sales brochures today like performance used to be.
The free market is the ultimate form of democracy. If you use your dollars to buy a 50 mpg car instead of a 11 mpg behemoth, you just voted for 50 mpg cars. The fact that you don’t see the streets filled with 50 mpg cars means you lost that election. Some people think this freedom of choice is a bad thing, I don’t.
Demand fuel efficient cars, and actually buy them, and they will build them, or else their dealers will be sitting with a showroom full of cars they can’t sell.


#14

ok4450 - The fuel mileage on the road will be very little different between a 3100 lb car and a 3400 lb car unless you are driving in the mountains. The difference in stop and go traffic will be greater.
Most people pay great attention to their gas mileage on the road. I do the same thing myself, but most of my gas is burned up around town.
As Spock said, “Humans are not logical.”


#15

Interesting “new” technology. Cragar mag wheels have been built welding their steel rims to aluminum centers for a long, long time. Seems counter intuitive but there it is.

This will allow GM to add stiffness (steel is stiffer than aluminum) in exactly the places it is needed so aluminum can be used for the rest. Previous methods of attaching Al to steel included rivets and/or glue.

Weight is a large part of fuel economy. Every acceleration requires fuel based on the weight it has to accelerate. Steady state rolling down the highway, it doesn’t mean that much but in start-stop traffic, it matters a lot. The old – Force (fuel) = Mass (weight/gravity) x Acceleration – still holds.


#16

@Mustangman - those Cragers weren’t welded, they were crimped. The steel rim has conical dimples every few inches to hold the center in place. I changed a lot of them at the garage. If you weren’t carful the center alloy could be cracked by the force of the tire changing machine…don’t ask.

edit-looking for any info on how they were made in the '60s I came up with not much. Best I can tell the center alloy hub was cast into the steel rim, not crimped. But not welded…


#17

Quoth B.L.E.: ‘The automakers then found that safety could be used to sell huge gas guzzling cars and today most cars exceed the minimum safety standards due to consumer demand.’

Safety doesn’t matter to a driver alone, but to riders and victims, and we all pay through medical insurance and taxes for the injuries people inflict upon themselves. There are still many who drive recklessly, don’t replace their airbags, don’t fasten their seat belts…

Quoth B.L.E.: ‘The free market is the ultimate form of democracy.’

But we use (and all pay for) the same roads, breathe the same air, pay for medical care collectively, pay for foreign policy that supports oil thugs.

The Constitution charges the government to ‘promote the general welfare’ (right after ‘provide for the common defense’); safe roads, clean air, cheaper gas are parts of ‘general welfare’.

Quoth B.L.E.: ’ If you use your dollars to buy a 50 mpg car instead of a 11 mpg behemoth, you just voted for 50 mpg cars.’

And voted to keep the price of gas down, which benefits Mr/Ms 11 mpg behemoth.

Quoth B.L.E.: ‘Some people think this freedom of choice is a bad thing’

The polluters get to decide how dirty everyone’s air is unless everyone, through the mechanism of government, limits them; the same for safety. Freedom of choice is more complicated than you presume.

Quoth B.L.E.: 'Demand fuel efficient cars, and actually buy them, and they will build them, or else their dealers will be sitting with a showroom full of cars they can’t sell. ’

You make the wrong argument. There’s more saving in making a 10-mpg behemoth an 11-mpg behemoth than making a 35-mpg into a 50-mpg: that’s how fuel-efficiency requirements make the most difference: making all vehicles more efficient.


#18

@texases I swear my Cragar mags had weld bead on the back with steel rims and an aluminum center. This link has pictures below from a classic 60’s Cragar SS shows exactly that. How did they do that? Looks like a steel weld bead locks the center in place.

https://google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=&url=http%3A%2F%2Fwww.ebay.com%2Fitm%2F2-Vintage-Cragar-S-s-Ruedas-15x4-Skinny-Cabeza-5-1-2-x-5-patron-Gasser-%2F260970452049%3F_ul%3DAR&psig=AFQjCNGevsHo07-Mu3MM5_c97rMqMPFAjw&ust=1464204532447625


#19

Here’s my best guess - we’re looking at steel blocks welded onto the steel rim to lock the alloy centers in place. There’s no way I know of they could have welded steel to aluminum.


#20

Yes, they melt at temperatures so different that aluminum would be a puddle before the steel would melt. It might be that the aluminum melts and joins to solid steel. Welding from the aluminum standpoint and brazing for steel.

Galvanic corrosion needs an oxidizer. If the joint is covered and never comes in contact with air or water, oxidation won’t occur. By covered, I mean paint or plating.