Degradation mechanism of AISI 316L, 321H, and 347H alloys in ternary molten salt vs solar salt
J. Chaves, María Isabel Lasanta, Gustavo García-Martín, María Teresa de Miguel, F.J. Pérez
Abstract
• This work investigates the corrosion mechanism of AISI 316L, 321H, and 347H alloys in Solar salt and LiNO 3 -additivated salt at 580 °C. • Alloy 347H exhibits the lowest corrosion rates: 0.035 mm/y in Solar salt and 0.027 mm/y in lithium-additivated salt. • The study identifies protective oxides like Cr 2 FeO 4 and Fe 2 O 3 , ensuring material longevity in Concentrated Solar Power plants. • Oxides such as LiFeO 2 and LiFe 5 O 8 form in lithium-additivated salt, affecting material durability. • Lithium-additivated salt increases the thermal range by 19.5 %, from 312.28 °C to 373.23 °C compared to Solar salt. This study aims to evaluate the corrosion behavior of AISI 316L, 321H, and 347H stainless steels in Solar salt (60 % NaNO₃ + 40 % KNO₃) and a ternary molten salt (52 % NaNO₃ + 35 % KNO₃ + 13 % LiNO₃) at 580 °C. The importance of this work lies in understanding corrosion mechanisms and optimizing salt compositions for improved material durability and thermal performance. Results showed that 347H exhibited the lowest corrosion rates, 0.035 mm/y in Solar salt and 0.027 mm/y in ternary salt, outperforming 316L and 321H in both environments. The ternary salt demonstrated a higher thermal operating range (373.23 °C vs. 312.28 °C for Solar salt), offering potential advantages for CSP applications.