1. A metal disk, intended, in particular, for use in agriculture, containing a plastic central part (10), intended, in particular, for mounting the disk on a chassis or similar element, and an outer peripheral part (12), intended, in particular , for tillage and having a higher hardness than the central part (10), characterized in that it further comprises a transition zone (14) between the central part (10) and the peripheral part (12), which has a gradient of hardness in radial stress Above, and, at least in its central part, the disk has a gradient of hardness in thickness. ! 2. The disk according to claim 1, characterized in that the difference in hardness between the central part (10) and the peripheral part (12) is at least 200 MPa (or 20 kg / mm2). ! 3. The disk according to claim 1 or 2, characterized in that the hardness of the peripheral part (12) is at least 1900 MPa (or 190 kg / mm2). ! 4. A disk according to one of claims 1 or 2, characterized in that the hardness of the central part (10) is preferably in the range from 1500 to 1700 MPa (or from 150 to 170 kg / mm2). ! 5. The disk according to one of claims 1 or 2, characterized in that it is made of a steel alloy alloyed with boron and containing manganese, chromium and silicon, as well as containing from 0.35 to 0.42% carbon and at least 0.16% chromium. ! 6. The disk according to one of claims 1 or 2, characterized in that the difference in hardness in the thickness of the disk in the zone with a gradient of hardness in thickness is from 20 to 150 MPa (or from 2 to 15 kg / mm2). ! 7. The disk according to one of claims 1 or 2, characterized in that a hardness gradient across the thickness of the disk is present in the central part (10) of the disk, as well as in the transition zone (14). ! 8. Drive one at a time1. Металлический диск, предназначенный, в частности, для использования в сельском хозяйстве, содержащий пластичную центральную часть (10), предназначенную, в частности, для крепления диска на ш
