Intergranular corrosion of AISI 316L steel
Résumé
The degree of sensitization (DOS) of austenitic stainless steel AISI 316L to intergranular corrosion (IGC) was determined by means of electrolytic etching in oxalic acid and electrochemical potentiokinetic reactivation (EPR) tests completed by metallographic inspection. An analytical electron microscope, equipped with an energy-dispersive X-ray spectrometer, was used to examine the microstructure of the steel investigated, which had been annealed for 3.60 x 10(4) to 1.91 x 10(7) s at a temperature of 650 degreesC. The kinetics of precipitation of secondary phases (M(23)C(6) carbides, Laves phase Fe,Mo) were studied by means of quantitative metallography. The volume fractions of chromium-rich M(23)C(6) carbides along grain boundaries and Laves phase Fc Mo in the matrix were determined. Chromium concentration profile measurements across the grain boundary, in the vicinity of M(23)C(6) carbides, have been performed using the analytical electron microscope. All results concerning microstructural changes were quantitatively related to the IGC characteristics by statistical normalization