Acoustic Activity of Intergranular Corrosion Sensitized AISI 304L in Double‐Loop Electrochemical Potentiodynamic Reactivation Test

ABSTRACT Intergranular corrosion (IGC) susceptibility of sensitized AISI 304L stainless steel is analyzed performing the Double‐Loop Electrochemical Potentiodynamic Reactivation (DLEPR) test and Acoustic Emission (AE) monitoring simultaneously. For IGC sensitization, controlled heat‐treatment is carried out at 600°C for 48 h. The non‐sensitized reference state is obtained by solution annealing at 1050°C for 30 min followed by water quenching. The DLEPR test is conducted in a conventionally used H 2 SO 4 + KSCN solution, but the scan rate was significantly reduced compared to the referenced literature, allowing a better detection and separation of acoustic active corrosion processes. The correlation of DLEPR and AE data reveals the highest acoustic activity in the DLEPR activation peak for the IGC‐susceptible state. The frequency‐based AE signal analysis exhibits a highly pronounced corrosion degradation of superimposed IGC, passive‐film rupture and pit initiation.