If you touch two pieces of the same type of metal together in the vacuum of space, they will fuse, bound together until eternity (or until you break them apart).
In space, if unprotected pieces of metal touch each other, they stick together permanently. This is also called Cold Welding and can be artificially applied in a vacuumed environment.
This doesn't happen on Earth, because the oxygen in our atmosphere forms an extremely thin film of oxidized metal on every exposed surface. The oxidization layer acts as a barrier that conveniently prevents chunks of metal from sticking to other chunks of metal.
In the vacuum of space, however, there is no oxidation layer. If the atoms of two metal objects come in contact with each other, what you suddenly have is one continuous metal object.
If you consider the Universe as a whole, metal objects sticking together at the drop of a hat is the norm. It's only in special places like Earth, with our highly caustic oxygen-rich atmosphere, that we can carry around bare pieces of metal to hit each other with and not have to worry about how inconveniently sticky they are.