Effect of Film-Forming Amines on the Acidic Stress-Corrosion Cracking Resistance of Steam Turbine Steel

Abstract

This work evaluates the effect of film-forming amines (FFA) on the acidic stress-corrosion cracking (SCC) resistance of NiCrMoV turbine steel. Contact angle measurements show an increased hydrophobicity of the surface when coating the steel with oleyl propylene diamine (OLDA). According to potentiodynamic measurements and post-mortem scanning electron microscopy (SEM) analysis, anodic dissolution and hydrogen embrittlement still occur when the steel is FFA coated. In situ constant extension rate testing (CERT) in acidic aqueous environment at elevated temperature of FFA-coated steel shows a ductility gain compared to non-coated steel, explained by a decrease in both corrosion rate and hydrogen uptake.

Sodium silicate corrosion inhibition behaviour for carbon steel in a dynamic salt water environment

“…the measured E corr . [42,43] Based on this corrosion current density, an approximated inhibition efficiency can be defined as given in equation 1:…”

Stress Corrosion Cracking of Steam Turbine Steel: The Influence of Organic Acid Characteristics

“…All measurements were performed at 25 • C and for all tests a scan rate of 5 mV/s was applied. Further details about both the set-up and method used for conducting electrochemical measurements can be found in previous work [49,[55][56][57]]. Faraday's law, cf.…”

“…The relation between the organic acid concentration and the hydrogen proton concentration is given by Equation ( 14), whereas the link with pH is given by Equation (13). Linear relationships between corrosion rate CR (µm/year) and hydrogen proton concentration H + (mM), according to Equation (18), can be identified [49,56,57].…”