Correlation between microstructure and intergranular corrosion behavior of low delta-ferrite content AISI 316L aged in the range 550-700 degrees C

摘要

The microstructure and the phase identification of austenitic stainless steel AISI 316L with low d-ferrite content (delta <= 1%) and aged for up to 80 000 h at temperatures ranging from 550 to 700 degrees C were investigated by using an optical microscope (OM), a scanning electron microscope (SEM) and a transmission electron microscope (TEM). Local changes of chromium content, resulting from nucleation and growth of chromium-rich phases during aging, were quantitatively assessed by energy dispersive X-ray spectroscopy (EDX) in the scanning transmission electron microscope (STEM). The intergranular corrosion behavior (IGC) of annealed and aged specimens was evaluated using the double loop electrochemical potentiokinetic reactivation (DL-EPR) and completed by IGC morphologies according to the ASTM A262 practice A standard.