A LAYER GROWTH-MECHANISM PROPOSED ON STUDIES ON A GAS NITRIDED AISI-316-L AUSTENITIC STAINLESS-STEEL

In this work an austenitic stainless steel AISI 316 L (1.4404) was gas nitrided at 540 degrees C. The nitride layer was characterised by mea ns of X-ray analysis, SEM, TEM and electron probe X-ray analysis. A fi ne lamellar structure comprising epsilon and gamma' nitrides was forme d. Nickel paritioned into gamma'-Fe4N type nitride while chromium part itioned into the epsilon-Fe2-3N type nitride. A layer formation mechan ism was proposed considering a local partition of the alloying element s Cr and Ni.