Irradiation-induced corrosion tendencies evolution at the phase boundaries containing carbides in duplex stainless steel.

Irradiation-assisted stress corrosion cracking normally initiates and propagates along grain/phase boundaries. Here, by using scanning Kelvin probe force microscopy, we characterized the Volta potential difference (VPD) changes prior and after proton irradiation at austenite/carbide (γ/C), ferrite/carbide (δ/C) and austenite/ferrite (γ/δ) interfaces in a 308 L stainless steel. It was found that, prior to irradiation, γ/C boundary had the lowest VPD, followed by δ/C and γ/δ. VPDs of all three types of phase boundaries slightly decreased after proton irradiation, wherein the γ/C boundary showed the largest VPD drop, followed by δ/C and γ/δ. The γ/C interface demonstrates the highest tendency of corrosion. [Display omitted] • The role of carbides at phase boundaries on IASCC is evaluated. • Irradiation promotes corrosion at γ/C, δ/C and δ/γ interfaces. • The γ/C interface shows the lowest Volta potential and even more so upon irradiation. • The Cr content seems to dominate the corrosion tendency evolution at all types of interfaces. [ABSTRACT FROM AUTHOR]