Influence of Secondary Phase Precipitation on Resistance to Intergranular Corrosion of AiSi 316l Austenitic Stainless Steel
Influence of Secondary Phase Precipitation on Resistance to Intergranular Corrosion of AiSi 316l Austenitic Stainless Steel

Summary/Abstract: The AISI 316L steel after cold working of 40% and subsequent annealing at 750°C for 1, 2, 5, 10, 50, or 100 h was investigated. For the microstructure characterization the light microscopy and the transmission electron microscopy were used. To determine the sensitivity to intergranular corrosion the test was performed according to ASTM A 262, practice A. The transition between non-sensitised and sensitised states was found to be between 1 and 2 h of annealing. Sigma, laves and chi phases were identified in all the analyzed conditions. M23C6 was found to start to precipitate between 5 and 10 h of annealing. Sigma, chi, and M23C6 precipitated mainly along the grain boundaries. Laves precipitated mainly inside the grains, and after 50 h of annealing also intergranularly. Time dependent changes in the average metal composition of particular phases were considered as negligible.

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