A516壓力容器用鋼在含NaCl水汽環境的腐蝕行為

The Corrosion Behavior of A516 Pressurized Vessel Steel in a Simulated Water Vapor Containing NaCl Environment

本研究主要是在探討A516壓力容器用鋼在模擬含NaCl水汽環境，於相對模擬溫度200℃至400℃間的大氣腐蝕行為，同時，對母材表面採用鍍鹽及未鍍鹽兩種情形，以探討其腐蝕行為的差異性。研究結果顯示，鍍鹽及未鍍鹽之鋼材的腐蝕動力學在各溫度下皆遵守拋物線定律。且鍍鹽後均較未鍍鹽者快，另外溫度愈高腐蝕速率也愈快。在腐蝕物觀察上得知，腐蝕產物主要是Fe2O3 及Fe3O4，而FeOOH及FeCl3．nH2O次之。在鍍鹽之母材腐蝕試片的橫截面分析中，發現氯離子在內層聚集並有往基材侵蝕的現象。

The atmospheric-corrosion of the pressurized-vessel steel(ASTM-A516) was studied over the temperature range of 200-400℃ in a simulated water vapor containing NaCl environment. The effect of NaCl surface coating (2 mg / cm2) on the corrosion kinetics was also evaluated, as compared with those without coating. The results showed that the corrosion kinetics of A516 steel obeyed the parabolic rate law, regardless of temperature and coating. In general, the corrosion rate increased with temperature, and the rates of the steel with NaCl coating are higher than those without coating at all temperature. The corroded scales formed on the steels (with or without NaCl coating) consisted of mostly Fe2O3. Fe3O4, and minor FeOOH and FeCh3-nH2O. The chlorine ion was always detected to be located at the interface between the substrate and the interior scales on the steel with NaCl coating, leading to further corrode the substrate, as a consequence of the faster corrosion rate.