This disk is a metal disk comprising a central ductile portion (10), particularly used for attaching the disk to a chassis or the like, and an outer circumferential portion (12), particularly for working on land and having a hardness greater than that of the central portion (10). The disk also has a transitional area (14), between the central portion (10) and the circumferential portion (12), that has a hardness gradient in a radial direction, and at least in the central portion (10), a hardness gradient is present in the body of the disk.
