If you took two clean, polished, identical wrenches into space, and then touched them together, you would end up with one large, misshapen wrench. The two wrenches would fuse together as if they'd been welded, without any application of heat or any pressure on your part. This is an effect known as 'cold welding'.
Cold welding occurs because space is a vacuum. It couldn't be achieved on Earth because metals form a protective oxide layer from being exposed to the atmosphere. In space, with no atmosphere, there is no way of the atoms from the two individual wrenches 'knowing' that they're not part of the same wrench, so they bond together and fuse. It's an issue that spacecraft and satellite designers have to bear in mind - and possibly also has beneficial implications for steel construction within a vacuum on Earth.