Synergistic effect of cold work and hydrogen charging on the pitting susceptibility of 2205 duplex stainless steel

Solution-treated 2205 duplex stainless steel (DSS) was cold-worked to different degrees and then charged with hydrogen. The pitting susceptibility and passivation of cold-worked 2205 DSS samples in neutral chloride solutions were investigated by chemical immersion, potentiodynamic polarization, potentiostatic polarization, and electrochemical impedance spectroscopy measurements. The dislocation densities in austenite and ferrite inside 2205 DSS samples both increased as the degree of cold work increased from 0% to 80%. After hydrogen charging, the hydrogen content in 2205 DSS samples increased from 13.52 ppm to 41.49 ppm as the degree of cold work increased from 0% to 80%, accompanied by an increased tendency to form hydrogen blisters. Deformation alone had little effect on the corrosion performance of 2205 DSS samples, but the deterioration effect of hydrogen charging on pitting resistance has been promoted by cold work, which could be ascribed to the increased hydrogen content as the degree of cold work increased. The change in pitting potential before and after hydrogen charging was linearly dependent on the hydrogen content in 2205 DSS samples. Pits preferably nucleated within austenite or at the austenite/ferrite boundaries for the hydrogen-charged 2205 samples regardless of the degree of cold work. (C) 2019 Elsevier Ltd. All rights reserved.