Forging Dissimilar metals

[rShell]

I don't have a lot of experience with the forging process. I learned about it way back in school, but professionally, I have not been involved with forgings too much, so this might sound like a dumb question. Can you create a forging using two pieces of dissimilar metals? Sort of like an insert mold. I am looking at a specialized hub for a wheel chair wheel. The current piece is an aluminum forging. I would like to put a steel insert into the part. Is this even possible?

Thanks.

rShell

 

[btrueblood]

The most common way to put a hard point in an aluminum part is using a coiled thread insert (helicoil) or rigid insert (keensert).

But no, to answer your question, it is not possible to forge aluminum and steel (or any other set of materials with widely varying metallurgy) in the same operation, and it would be tricky at best to forge aluminum over a steel insert.

 

[swall]

It is hard to provide a good answer without seeing a drawing, but I suspect forging is not a workable solution. Casting with an insert, as suggested by btrueblood seems like a better path. If your parts have rotational symmetry, friction welding would be another possibility.

 

[btrueblood]

I don't think you can weld a steel insert into an aluminum part? Again, the metallurgy to create a bond is just not there, and the expansion and melting point differences between the two materials tends to have them tearing apart before the joint cools to room temp. Could be wrong, as it's been a few years since I did much with aluminum. Generally, however, polymer adhesives and/or mechanical fixtures are used to mate steel and other materials to aluminum, and if exposed to weather, a lot of effort is expended to get the right coatings to reduce corrosion.

 

[rShell]

Thank you Gentlemen.
I thought this would be the answer, from what little I know about forging. But just wanted to make sure before I got too far down that path.

rShell.

 

[mfgenggear]

rshell

are you looking for an inner steel ring for wear?
it is possible to shrink/press fit to dissimilar metal after machining.



Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[BrianE22]

Centrifugal casting is used to put a non-steel outside material on steel hubs:

http://www.accuratespecialties.com/spuncast-gear-blanks

 

[swall]

btrueblood--I have experience with a product where an aluminum tube was friction welded to a machined steel yoke. It was a torsion bearing member. So, yes, it can be done. Success is highly dependent on geometry and it is beneficial to create a mechanical bond in addition to the "weld".

 

[mfgenggear]

plasma spray is an other option.

Mfgenggear
if it can be built it can be calculated.
if it can be calculated it can be built.

 

[dvd]

Hot forging temperatures for aluminum and steel are nowhere close.

Seems like the aluminum and steel would have to have similar yield strengths to cold (or hot) forge, or the weaker material will squirt all over the place whilst the stronger material remains obstinate.

 

[btrueblood]

Thanks swall, learn something new every day.

 

[dgallup]

You can also join dissimilar metals with explosion welding. I doubt that would be appropriate in this case, just wanted to say it can be done.

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