For higher stresses and thicker of the part, it is necessary to switch to alloy case-hardening steels: to 16MnCr5 or, for higher hardenability, to 20MnCr5. Similar to the last two steels is 16NiCr4, which due to the presence of nickel, has a higher toughness, a property which in the case of 20NiCrMo2-2 can also be achieved with larger workpieces. 17NiCrMo6-4 is the case-hardening steel par excellence: its chemical composition allows the best performance to be obtained even with large workpieces. Gieffeacciai also has the possibility of supplying two of these grades in their leaded version, 16NiCrS4Pb and 17NiCrMoS6-4Pb, which guarantee better machinability.