During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron micr...During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron microsco- py, microstructure of the as-received X80 steel was confirmed to be acicular ferrite, while the microstructures of quenched, normalized and annealed X80 steels were lath bainite, granular ferrite and quasi-polygonal ferrite, respec- tively. After immersion in the simulated acidic soil solution for 48 h, corrosion rates of these four steels were deter- mined by mass loss measurements and corrosion products were examined by Raman spectroscopy and X-ray photoe lectron spectroscopy. Scanning vibrating electrode technique was used to characterize the micro-galvanic corrosion be- haviors of the synthetic bimetallic electrodes which were formed by coupling each of the simulated HAZ microstruc- tures with the as-received steel in direct physical and electric contact. It is demonstrated that the as-received steel acts as cathode in the as-received/quenched and as-received/normalized couples, while the annealed steel acts as cathode when coupling with the as received steel. The distinction of current density between the galvanic couples reduces with prolonging the immersion time.展开更多
基金Sponsored by National Natural Science Foundation of China(51171025,51131001)Beijing Postdoctoral Research Foundation of China(2013M540829)
文摘During heat treatment processing, microstructures of heat affected zone （HAZ） were formed in X80 pipe- line steel. After observation by optical microscopy, scanning electron microscopy and transmission electron microsco- py, microstructure of the as-received X80 steel was confirmed to be acicular ferrite, while the microstructures of quenched, normalized and annealed X80 steels were lath bainite, granular ferrite and quasi-polygonal ferrite, respec- tively. After immersion in the simulated acidic soil solution for 48 h, corrosion rates of these four steels were deter- mined by mass loss measurements and corrosion products were examined by Raman spectroscopy and X-ray photoe lectron spectroscopy. Scanning vibrating electrode technique was used to characterize the micro-galvanic corrosion be- haviors of the synthetic bimetallic electrodes which were formed by coupling each of the simulated HAZ microstruc- tures with the as-received steel in direct physical and electric contact. It is demonstrated that the as-received steel acts as cathode in the as-received/quenched and as-received/normalized couples, while the annealed steel acts as cathode when coupling with the as received steel. The distinction of current density between the galvanic couples reduces with prolonging the immersion time.
