At Sheffield there's an industrial museum called 'Kelham Island', which I've been to visit occasionally, it's quite an interesting place.
The reason for mentioning this, is that Sheffield is one of the most famous metal working cities in the world, and one of the exhibits there is a welding sample from a local college. It's basically a ring of various different metal segments, all welded together (imagine a dart board with a hole in the middle), then sawed through to make a nice even slice and polished. It's reason is to show that all sorts of difficult metals can be welded to each other (with sufficient skill), it's truely an impressive sample!.