Two grades of AISI 316L(N) austenitic stainless steels differing only in copper content (0.083 and 0.521 wt.%), showed remarkable difference in resistance to sensitization and susceptibility to intergranular corrosion. Different thermal treatments were carried out with an overall objective of altering the nature of the grain boundary. An attempt was made to correlate the degree of sensitization (DOS) with various microstructural parameters such as grain size and grain boundary nature. No clear trend could be established between the individual parameters and DOS. Effective grain boundary energy (EGBE), which is a combined parameter showed clear trend with DOS. The presence of 0.521 wt.% of copper brings down EGBE remarkably leading to improved resistance to sensitization.