Taloring the profile
Carbon and nitrogen – a smooth profile
The dissolution of carbon and nitrogen is a key feature of the ExpaniteLow-T process. Nitrogen adds increased peak surface hardness while carbon bridges the gap to the relatively soft base material. The consequence is a smooth transition in hardness from the hardened zone to the base material, as illustrated in the composition/hardness profiles.
Gaseous surface hardening allows thermodynamically controlled formation of Expanite® "layers" contrary to hitherto applied plasma and salt bath based methods. Consequently, tailoring of a combination of individual carburizing and nitriding potentials is indeed possible, which implies large flexibility in tailoring the materials properties whether galling resistance or durability is required for.
The smooth composition profile is crucial for the enhancement of the load bearing capacity and fatigue strength.