Localized Corrosion Behavior of UNS N07718 in a Solution Simulating a Diluted-sour Environment

The localized corrosion behavior of precipitation-hardened UNS N07718 was investigated by immersion tests in 6 wt% FeCl<sub>3</sub> + 1.0 HCl and the use electrochemical techniques a simulating solution diluted-sour environment 25 NaCl 0.5 CH<sub>3</sub>COOH. Ti carbides Nb-Mo with 1-10 µm size were distributed alloy. After at temperature higher than 45<sup>o</sup>C, depth over identified, critical pitting determined to be 45<sup>o</sup>C. Potentiodynamic polarization showed that surface immediately passivated experimental solution. passivity-maintaining current density gradually increased increasing temperature, finally, initiated or propagated V<sub>SSE</sub> 80<sup>o</sup>C. interface between alloy substrate. Scanning Kelvin probe microscopic images revealed contact-potential difference values order carbide > substrate, indicating substrate act as cathode an anode, respectively, forming micro-galvanic couple. Therefore, it is concluded substrates N07718.