Synergistic Corrosion Mechanisms of Alloys in High-Temperature and High-Pressure Water Environments: A Review

High-temperature and high-pressure (HTHP) water serves as a critical heat-exchange and reaction medium in numerous industrial applications. Under these extreme conditions, water exhibits distinct physicochemical properties that significantly elevate the corrosion susceptibility of alloys. This study investigates the mechanisms of oxidative corrosion, electrochemical corrosion, and stress corrosion cracking (SCC) in alloys exposed to HTHP water. From a synergistic perspective, it elucidates how interconnected phenomena—namely, accelerated oxide layer rupture, enhanced ion diffusion, and localized stress concentration—markedly accelerate alloy degradation. The findings reveal that reduced intermolecular hydrogen bonding, increased electrical conductivity, and heightened activity of corrosive ions in HTHP water are critical drivers of corrosion. By analyzing molecular structures and dynamics, it clarifies the complex interplay among HTHP water properties, corrosive ions, electrochemical reactions, and mechanical stress, thereby enhancing the understanding of alloy failure mechanisms. These insights provide a theoretical basis for designing corrosion-resistant materials and equipment.