There are (complex) ways to braze aluminum to steel, but not weld (until now, it seems). Can’t wait to find out the details.
Miss the SS mags ,they really looked sharp on a big car,there are styled steel wheels now that are pretty light,I swear the alloys I got for my Dakota feel as heavy as the styled steel ones that came on it stock,the factory alloys are pretty thick .
Thats the quandary of an aluminum dump truck bed ,sure it saves some weight ,but due to the thickness necessary(for wear rates ) you dont save as much weight as you would imagine an aluminum truck bed the same gauge as a steel bed would quickly wear out ,the pit materials are for the most part very abrasive .
Galvanic corrosion generally needs an electrolyte for ion exchange and two metals far enough apart in the "electromotive series for vigorous ion exchange to occur(think a battery ) simple oxidation only requires a reactive metal and oxygen(aluminum is highly reactive,scarcely noble at all,only the tough oxide layer protects it from further oxidation.
An interesting property of aluminum is that when in contact with Mercury .it will react and form a powder resembling rust .Some airlines will not let you carry mercury thermometers on board.
The melting temp of aluminum at standard room pressure (29.92in hg) is 659F. Mild steel is 2,070F.
I recognize that these temperatures can be changed by alloying the metals and by applying the heat under different environmental conditions… like in inert gasses and in different environmental pressures, but I wouldn’t buy a vehicle made this way until the process had been very well proven. The type and extent of structural changes to the elements and their effects of them on resistance to (or promotion of) oxidation in extreme environments and to strength would have to be super well studied, and even then I’d feel unsafe.
GM has a history of testing unproven technologies on the consumers. Ask me about my Vega. I don’t have a warm fuzzy feeling about this one.
The melting temp of aluminum at standard room pressure (29.92in hg) is 659F. Mild steel is 2,070F.
Are you sure those aren’t Celsius temperatures? If aluminum melted at that low a temperature, my aluminum bullet molds would have been ruined long ago.
Must be centigrade,sounds like He was talking about lead .
Melting point Aluminum (Al) 658 Celsius, Steel (Fe) 1538 Celsius.
Steel usually has a slightly lower melting point than pure iron does. In fact many alloys melt at a lower temperature than either of its components, solder is a good example.
Also, most iron alloys become soft long before they actually melt, a property blacksmiths take advantage of when they forge a part with a hammer.
The fact that steel doesn’t have to melt in order to lose most of its strength is a fact that seems to be lost on 911 truther conspiracy theorists who claim a jet fuel fire cannot get hot enough to melt steel.
If you want to amaze people and win a bet, bet someone that he can’t pick up a red hot nail with a strong magnet. That red hot nail will ignore that magnet, its as if the nail was make out of some non magnetic material. As the nail cools, it will suddenly become magnetic again.
Humble apologies to those who corrected my F to C. Mea culpa.
I no longer have the ASME standards handy, but there’s a substantial difference in the melting point of the two, to the extent that if I recall correctly aluminum will vaporize far too early to be welding it to steel.
But the real concern I have is GMs history of testing ideas that shouldn’t be pursued on the customer base. This sounds to me like one of those ideas. I’d rather avoid another disasterous adventure with GM experimentation. Been there, done that.
I found this interesting so started looking around. I found all the GM patents and also one that dates back to 1964! That latter one was some Russians that receive a U.S. patent for their invention in joining steel and aluminum. The newest patents seem to leverage this earlier one in that they employ plating or an insert metal to make the joint. This article has some further insight into the process- http://www.wsj.com/articles/the-holy-grail-of-welding-steel-aluminum-1423528185
I wish I could see that WSJ article. Any other links?
Why can’t you? I have no special permissions, I just opened it up. What do you get when you try?
I see the first few lines, then an invitation to subscribe.
Here’s an older article about how GM is using modified spot welding for aluminum, instead of adhesives (as Ford is doing).
http://www.autonews.com/article/20141124/OEM06/311249975/as-ford-spends-big-gm-joins-aluminum-with-simple-welds
Here’s a surprisingly uninformative SAE article:
http://articles.sae.org/14838/
Seems like the spot welding technology is similar to that in the above article. I don’t understand how a special electrode will solve the issue on creating the joint between steel and aluminum.
They can lower the heat transfer on one side and increase it on the other with different footprints…
Yeah, you’ve got to be a member to read it. Not being an engineer or science guy, I can’t convert the temps in my head. So 658C=1216F, and 1538C=2800F, rounded of course for simplicity. All I know is I can melt aluminum with my propane torch but mapp gas is faster. Hard drive platters are fun to melt and those magnets are magnificent. But watch your fingers, those things can break a finger if you aren’t careful.
If they’re using adhesives, they’re not welding. They’re bonding.
Even if they’ve figured out how to spot weld the two, just because you CAN do something doesn’t meant you SHOULD.
Quoth B.L.E.: 'Steel usually has a slightly lower melting point than pure iron does. In fact many alloys melt at a lower temperature than either of its components, solder is a good example.'
The 'eutectic' of any alloy is the composition that melts at the lowest temperature, lower than the melting point of any of its components. 63% tin, 37% lead is the tin-lead eutectic.
Quoth B.L.E.: 'If you want to amaze people and win a bet, bet someone that he can't pick up a red hot nail with a strong magnet. That red hot nail will ignore that magnet, its as if the nail was make out of some non magnetic material. As the nail cools, it will suddenly become magnetic again.'
Ferromagnetism is a property that relies on a material ordering itself into magnetic domains; above a certain temperature, its Curie temperature, it won't magnetize.I’m interested in the details of the process too, @texases.
@“the same mountainbike”, if you live to 600, you will grouse about GM and your Vega. That was about 40 years ago. All the auto companies have their flops. I think GM has come a long (good) way since the 1970s, as have most of the auto builders.