Greaves

From DwarfFortressWiki

Greaves are part of the Plate Armor set and covers the lower body. An activated military dwarf set to use heavy armor will use greaves if a set is available.

They can be made from metal, bone and shell. For bone greaves you need 3 stacks of bones, no matter how many single bones are in the stacks.

The Heavy armor set:
Head: Helm

Upper Body: Plate mail

Lower Body: Greaves

Feet: Boot

Hands: Gauntlets