Intergranular corrosion of AISI 316L steel

The degree of sensitization (DOS) of austenitic stainless steel AISI 316L t o intergranular corrosion (IGC) was determined by means of electrolytic etc hing in oxalic acid and electrochemical potentiokinetic reactivation (EPR) tests completed by metallographic inspection. An analytical electron micros cope, equipped with an energy-dispersive X-ray spectrometer, was used to ex amine 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 k inetics of precipitation of secondary phases (M23C6 carbides, Laves phase F e,Mo) were studied by means of quantitative metallography. The volume fract ions of chromium-rich M23C6 carbides along grain boundaries and Laves phase Fc Mo in the matrix were determined. Chromium concentration profile measur ements across the grain boundary, in the vicinity of M23C6 carbides, have b een performed using the analytical electron microscope. All results concern ing microstructural changes were quantitatively related to the IGC characte ristics by statistical normalization. (C) 2001 Elsevier Science Inc. All ri ghts reserved.