Insights into the role of partially mixed zones in sulfide stress corrosion cracking of the inconel 625/X80 weld overlay

Sulfide stress corrosion cracking (SSCC) behavior of the fusion boundary (FB) region of Inconel 625/X80 weld overlay was investigated with a focus on the role of the beach and peninsula partially mixed zones (PMZs). Compared to the martensite-ferrite boundary, the large misorientation and low deformation compatibility of the austenite-martensite boundary promote the accumulation of hydrogen and thus increase the cracking suscep-tibility. Further, under the effect of local anodic dissolution and hydrogen accumulation due to the large dimension PMZ, the corrosion defect formed at the junction can be easily transformed into a crack. After SSCC initiation, the crack preferentially grows along the Inconel 625/PMZ interface while the austenite matrix may oblige the crack to propagate along the FB. In addition, the beach PMZ likely shows a higher SSCC susceptibility than the peninsula PMZ mainly because severe anodic dissolution in the peninsula structure blunts the crack tip along the FB during crack propagation. & COPY; 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The role of beach and peninsula partially mixed zones (PMZs) in sulfide stress corrosion cracking (SSCC) behavior of the fusion boundary (FB) region in Inconel 625/X80 weld overlay was investigated. The large misorientation and low deformation compatibility of the austenite-martensite boundary promote hydrogen accumulation and increase cracking susceptibility. Moreover, local anodic dissolution and hydrogen accumulation due to the large dimension PMZ can easily transform corrosion defects into cracks. After SSCC initiation, the crack mainly propagates along the Inconel 625/PMZ interface and the austenite matrix.