Iron Chain is a shaped crafting recipe that uses 3 items: 2 Iron Nugget and 1 Iron Ingot. Place the ingredients exactly in the pattern shown above. The pattern can sit anywhere on the grid as long as its shape stays the same. It needs the full 3×3 grid, so you have to use a crafting table.
… and 1 more recipe that use Iron Chain.
You need 2 Iron Nugget and 1 Iron Ingot — 3 items in total, arranged as shown in the crafting grid. The recipe gives you 1× Iron Chain.
Yes. The recipe needs the full 3×3 grid, which only a crafting table offers.
It is a shaped recipe: the arrangement matters. You can shift the pattern around the grid, but the shape must stay the same.
Iron Chain is an ingredient in 13 crafting recipes, for example Acacia Hanging Sign, Bamboo Hanging Sign and Birch Hanging Sign.