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High Temperature Corrosion And Stress Corrosion Investigations Of SS316 In Molten Nitrate Salt

Solar Salt has many desirable properties as an intermediate heat transfer fluid including low corrosion rates (<10 μm/yr) at temperatures (T) <600°C, high oxidizing power for capturing tritium, low melting point, and relatively low cost. However, higher temperatures (T > 600°C) and other factors e.g., high flow rates, can significantly increase corrosion rates.

Product Number: ED22-17168-SG
Author: Camilla A. Stitt, Andrew Brittan, George A. Young, Anne Demma, and Micah J. Hackett, Andrew Dong and Peter Hosemann
Publication Date: 2022
$20.00
$20.00
$20.00

The performance of 316 stainless steel in molten (60 wt.% NaNO3-40 wt.% KNO3) ‘Solar Salt’ has been assessed by corrosion testing, slow strain rate testing, and fracture mechanics-based stress corrosion tests. While solar salt has exhibited good compatibility with austenitic stainless steel at low temperatures, increased nitrate anion decomposition at ~600°C is known to increase corrosion rates. This work, combined with literature data shows that the corrosion kinetics can be described by a piecewise model that accounts for salt decomposition at elevated temperatures. However, additional research is needed to better describe corrosion rates at temperatures >600C. Consistent with previous work, under slow strain rate conditions, 316 stainless steel appears to be resistant to environmentally assisted cracking at temperatures ≤600C. However, fracture mechanics-based testing suggests that intergranular cracking can occur at 550C at a constant K=26 MPa√m at times on the order of 3 months.

The performance of 316 stainless steel in molten (60 wt.% NaNO3-40 wt.% KNO3) ‘Solar Salt’ has been assessed by corrosion testing, slow strain rate testing, and fracture mechanics-based stress corrosion tests. While solar salt has exhibited good compatibility with austenitic stainless steel at low temperatures, increased nitrate anion decomposition at ~600°C is known to increase corrosion rates. This work, combined with literature data shows that the corrosion kinetics can be described by a piecewise model that accounts for salt decomposition at elevated temperatures. However, additional research is needed to better describe corrosion rates at temperatures >600C. Consistent with previous work, under slow strain rate conditions, 316 stainless steel appears to be resistant to environmentally assisted cracking at temperatures ≤600C. However, fracture mechanics-based testing suggests that intergranular cracking can occur at 550C at a constant K=26 MPa√m at times on the order of 3 months.