Work

Stress corrosion mechanism of CLF-1 RAFM steel in flowing Pb-17Li at 450 °C: synergistic effects of tensile stress and microstructural evolution

Year: 2026

Type: article

Abstract: The compatibility of reduced activation ferritic/martensitic (RAFM) steel with liquid Pb-17Li is a critical concern for its application as a structural material in liquid metal blankets of fusion reactors. This study investigated the stress corrosion mechanism of CLF-1 RAFM steel under a tensile stress of 250 MPa for 5000 h in flowing Pb-17Li at 450 °C. The results indicate that stress-induced strain disrupts the continuity of the protective oxide layer, shortening the incubation period and increasing corrosion initiation sites, thereby intensifying the corrosion severity and susceptibility. The corrosion morphology is jointly influenced by the flow velocity of Pb-17Li and the steel’s microstructure. At high flow velocities, the martensitic lath structure is eroded, resulting in an etched surface. Conversely, lower velocities preserve the more corrosion-resistant laths, producing lamellar corrosion structures. Furthermore, shear stress promotes microstructural coarsening, which eliminates certain grain and sub-grain boundaries. Although this locally improves corrosion resistance, the resulting long and straight grain boundaries instead facilitates the penetration of liquid metal, thereby accelerating corrosion failure. These findings clarify the stress corrosion mechanism of RAFM steel in Pb-17Li and provide new insights for the modeling of liquid Pb-17Li corrosion and design of liquid metal blankets.

Source: Nuclear Fusion

DOI: 10.1088/1741-4326/aea0e4