Novel method for evaluation of stress assisted corrosion through compact tension specimens to assess material compatibility in latent heat thermal energy storage systems

Abstract

The next generation Concentrated Solar Power (CSP) plants integrated with Thermal Energy Storage (TES) offer a promising solution for dispatchability, reliability, and economic concerns associated with renewable energy technologies. However, the expected operational life of up to 30 years proves to be a major challenge due to the impact of high temperatures and corrosive eutectic salts utilised in the latent heat TES systems. Additionally, the system is under varying degrees of stress that can accelerate corrosion mechanisms. Unfortunately, this stress corrosion relationship is often neglected during the material compatibility assessment. This study utilises a novel static immersion testing approach with three designs of modified Compact Tension (CT) specimens manufactured from AISI 316L to investigate the interaction of alloys under stress with various eutectic salts at up to 750 °C for up to 1000 Hours. The results indicate that oxidation is accelerated up to four times and Intergranular Corrosion (IGC) up to two times in the high-stress region of the test samples. Furthermore, the findings suggest that static immersion testing using CT specimens can be regarded as an effective approach to assess the influence of stress on corrosion and conduct a reliable material assessment for latent heat TES systems and CSP plants.