SURFACE HARDENING OF GROUP IV METALS

The present invention relates to a method of case hardening a Group IV metal or a Group IV metal alloy and to components hardened in the method. The method comprising the steps of: providing a workpiece of a Group IV metal or a Group IV metal alloy, the workpiece being in its final shape; nitriding the workpiece in a nitriding atmosphere comprising NHs as a nitriding species at a first temperature in the range of 450°C to 750°C for a nitriding duration of at least 16 hours to provide a hydrogen containing diffusion zone; removing hydrogen from the hydrogen containing diffusion zone at a second temperature of up to 750°C and a partial pressure of H₂ of up to 10^-4 mbar over a hydrogen removal duration of at least 4 hours to provide a hydrogen depleted diffusion zone. The method and the component are useful for implants, in particular dental implants.