Sensitivity to hydrogen induced cracking, and corrosion performance of an API X65 pipeline steel in H2S containing environment: influence of heat treatment and its subsequent microstructural changes

In this investigation, the effect of microstructural changes and phase equilibria on corrosion behavior hydrogen induced cracking (HIC) sensitivity an API X65 pipeline steel was studied. For purpose, heat treatment performed at 850 °C, 950 1050 °C 1150 to engineer desired microstructure steel. Then, evolution by optical microscopy, Field Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive X-Ray Spectroscopy (EDS). Corrosion properties were evaluated in H2S environment open circuit potential (OCP), Potentiodynamic polarization Electrochemical Impedance (EIS). As well, HIC assessed charging cathode immediately conducting tensile test. analyses showed that is ferritic-pearlitic together islands martensite/austenite constituents. Increasing temperature reduced amount pearlite increased ferrite grain size. It also stabilized content. results indicated no active layer formed surface Also, increasing resistance micro-galvanic localized corrosion. suggested substantially reducing ferrite; i.e. lower temperature.