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Orrin
08-06-2011, 03:03 PM
In a salvage yard I stumbled across this four-foot length of 1 X aluminum/steel bar:

http://www.oldengine.org/members/orrin/temp/bar_2072.jpg

I had never seen anything like it, before. Does anyone know what application it would be used for?

Obviously, it was a complex undertaking to bond these two metals together. Look at the steel in this close-up. Obviously, those hooks were intended to provide the necessary "tooth" to ensure a mechanical bond between the two metals (scroll down to see the boundary zone).

http://www.oldengine.org/members/orrin/temp/tooth2089.jpg

Some folks have surmised that the aluminum was cast onto the steel. That could be; but, take a look at this polished cross-section, aluminum on top, steel on the bottom. Note the soft zone in the aluminum next to the steel. It appears to me to be a heat-affected zone. It has also occurred to me that it could be a layer with iron dissolved into it, such as if it were aluminum cast against steel. I seriously doubt, however, that iron would migrate that far and that fast into molten aluminum.

http://www.oldengine.org/members/orrin/temp/haz_2084.jpg

I'm guessing this is one way of fastening an aluminum superstructure onto a steel base; however, someone shot that idea down because of the potential for electrolysis between the metals.

Surely, there is someone out there who has worked with a product such as this. Please enlighten me.

Best regards,

Orrin

topct
08-06-2011, 03:17 PM
Armor plate is my guess. At the Kaiser rolling here mill we tried to make a similar product. A sandwich of two pieces of 7079 aluminum with a steel center. It did not work as we could not get a good bond. We tried several pieces for the experiment and it was sent back to the engineering dept and we never saw it again. They were supposed to be for doors on armored personnel carriers.

The idea was that an armor piercing round goes through the steel, fractures it, absorbing the shock, and the aluminum contains the shrapnel.

I of course, could be totally wrong.

vpt
08-06-2011, 03:21 PM
That chunk was most likely cut off a 4x8' or bigger sheet. I have seen something on TV about how they use explosives to bond the two metals together called blast welding. They mentioned these sheets are expensive and are used for stuff like chemical containers that need strength of steel but corrosion resistance of the other metal (in your case aluminum). They mentioned some used for aquatic applications in salt water and the like. Not much mention of anything else it is used for.

John R
08-06-2011, 03:24 PM
In shipbuilding it is used to join the alum superstructure to the steel hull
John R

fishfrnzy
08-06-2011, 03:24 PM
Could be made with explosive bonding this way. It looks to be the cut edge of a plate rather than a bar. http://www.dynamicmaterials.com/videos.aspx

I've seen the stuff and it looks kind of strange.

FYI in mining they usea a lot of chrome carbide overlay plate that looks similar with 60 RC hardfacing on the whole plate and mild steel on the beck to weld in areas of high wear. It is not smooton top surface but the cut edge looks the same. http://www.alabamahardsurfacing.com/uploads/SuperWearPlate2.jpg

John R
08-06-2011, 03:26 PM
It is explosive bonded in plates then cut to size
John R

Evan
08-06-2011, 04:04 PM
Aluminum can be bonded to steel quite well. A standard sheet metal product is aluminized steel. It is steel sheet that is hot dip coated with aluminum/silicon alloy much the same as galvanizing. The process must be done hot for it to bond but it bonds well.

Where problems occur is when the aluminum thickness is similar in absolute yield strength to the steel. Then separation will occur with temperature changes. A thin coat of aluminum will simply deform plasticly to accommodate the steel.

wierdscience
08-06-2011, 05:49 PM
What John said,it's also used to make aluminum and stainless lined vessels and tanks.

Forrest Addy
08-06-2011, 06:14 PM
Used to be an outfit by Port Angeles that explosive welded aluminum to steel in the earl '70's. They had a whopping big piece of battleship armor as a back-up. Set on a steel plate, space the aluminum a critical distance off the steel, and coat it with a critical thickness of explosive. Fusing was a real trick. The explosive had to be detonated instantly along one edge and most caps have some dither in their initiation. 10 microseconds at detonation speed is 3" - a significant amount is the wierd world of high velocity dynamics. One artifact of the bonding process was the corrugated interface. The plates were smooth clean sandblasted surfaces laid flat together but the explosive bonding put the little waves and corrugations in the bond.

We at Puget Sound Naval Shipyard used this material as was said: to join aluminum superstructure to steel deck by welding. We parted it off in 1" wide strips on a planer. The corrugated interface was a real tool breaker. Very abrasive for some reason.

Scottike
08-06-2011, 06:17 PM
It's explosive bonded plate as John said. The small defect/pinhole in the third picture is probably the reason the piece was scraped. There are a number of uses for the material. Aircraft tie down points on aircraft carriers (the steel gets welded to the deck) various space shuttle and aircraft parts where they need high strength, etc. The stuff come in a variety of flavors - Steel/ AL, Al/Cu, Al,Cu,Ti, and I'm sure there are others. A friend had the pleasure?? of machining a bunch of the Al,Cu,Ti material - not a lot of fun when the cutter hits the transition region (the Cu is used as a bonding layer between the Al and Ti)

http://www.highenergymetals.com/page2.html

topct
08-06-2011, 06:40 PM
Used to be an outfit by Port Angeles that explosive welded aluminum to steel. They had a whopping big pinxe of battleship armor as a back-up. Set on a steel plate scatter some particles of aluminum to space the aluminum a critical distance off the steel. Lay down the aluminum and coat it with a sheet of explosive a critical thickness. Fusing was a real trick. The explosive had to be detonated instantly along one edge and most caps have some dither in their initiation. 10 microseconds at detonation speed is 3" - a significant amount is the wierd world of high velocity dynamics. One artifact of the bonding process was the corrugated interface. The plates were smooth clean sandblasted surfaces laid flat together but the explosive bonding put the little waves and corrugations in the bond.

We at Puget Sound Naval Shipyard used this material as was said: to join aluminum superstructure to steel deck by welding. We parted it off in 1' wide strips on a planer. The currugated interface was a real tool breaker. Very abrasive for some reason.

And so you can see why the engineers at Kaiser were interested in producing such a composite by trying to roll forge them together. It would have been much cheaper to do.

I wish it would have worked, then I could say I was involved with the development of a valuable product. But it totally failed.

tdmidget
08-06-2011, 06:52 PM
" There are a number of uses for the material. Aircraft tie down points on aircraft carriers (the steel gets welded to the deck)"

No, I don't think they randomly weld scrap down to tie down aircraft.

http://www.defense.gov/photos/newsphoto.aspx?newsphotoid=5467

Looks like they don't need to.

WJHartson
08-06-2011, 07:15 PM
The leading producer of roll bonded material is in Spokane, Wa. Here is a link to their site. http://www.spurind.com/ A friend of mine owns the company.

topct
08-06-2011, 07:42 PM
The leading producer of roll bonded material is in Spokane, Wa. Here is a link to their site. http://www.spurind.com/ A friend of mine owns the company.

So someone figured it out.

And maybe the crude approach that Kaiser tried had something to do with the development after all?

The lot tickets did have the "experimental" word on them.

Weston Bye
08-06-2011, 08:48 PM
Aircraft tie down points on aircraft carriers (the steel gets welded to the deck)

Maybe things have changed, but wasn't so 40 years ago when I was on the America and the Enterprise. The Enterprise did, however have aircraft elevator decks back then, made of welded aluminum bar stock. That's where they staged the planes I worked on, and if anyone dropped a tool it invariably fell between the bars and ended up in the sea 90 feet below.