joining hot metal to cold metal

[engrnick]

I'm curious, what happens when you pour a molten metal, or a hot metal, onto a cooler version? For example, can I take molten aluminum and pour it on cold aluminum and have it bond? or does it need to weld?

i can't seem to find any info on it.

I ask because I'm curious if the cold aluminum will form its protective aluminum oxide coating quickly, or will the molten aluminum absorb the oxide? Will the oxide prevent the molten aluminum from bonding to the cold formed one? aluminum is good at bonding with itself, at least it seems to with galling, so I'm curious if it would bond to itself when it has energy.

I'm thinking of doing this for a research topic for my master's, but I can't seem to find any journals (or tech docs) on this - any tips on finding more info on this? If not aluminum, is there a steel that will bond hot with cold when poured on it?

Thanks,
Nick

 

[swall]

Typically, the best you can do is obtain a mechanical bond. Steel inserts are sometimes used in aluminum castings to provide threads or some other feature not attainable with aluminum alone.

 

[engrnick]

I changed my mind, found a few things saying that you can't fuse molten aluminum with set aluminum - the rapidly created oxide layer is problematic unless the material is in an inert gas environment like TIG/MIG welding.

also the temperature of the "cold" part seems to need to be heated to allow fusion.