Study on Corrosion Behavior of Q345qDNH Weathering Steel in Simulated Industrial Marine Atmosphere
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摘要: 以实际工程中的典型桥梁耐候钢为对象,通过周期浸润加速腐蚀试验,并使用宏观形貌观察、扫描电子显微镜(SEM)、X射线衍射分析(XRD)等方法,研究耐候钢锈层表面形貌、锈层物相组成、腐蚀失重及动力学曲线和电化学性质等的变化规律,探究了Q345qDNH典型耐候钢在模拟工业海洋大气环境NaHSO3和不同NaCl浓度下的腐蚀行为。
结果表明,在不同NaCl浓度的腐蚀环境下,耐候钢表面腐蚀产物均由α-FeOOH、γ-FeOOH、β-FeOOH、Fe2O3、Fe3O4构成,且腐蚀环境中NaCl浓度的大小与耐候钢的腐蚀失重速率呈正相关;当NaCl浓度为0.1%时,耐候钢的腐蚀失重速率随腐蚀时间的延长迅速降至低位后趋于平稳,在腐蚀1 440 h后锈层表面均匀致密,平均腐蚀失重速率约为0.76 g/(cm2·h);当腐蚀环境中NaCl离子浓度为3.5%时,耐候钢的腐蚀失重速率处于高位且随腐蚀时间的延长先增高后降低,在腐蚀1 440 h后锈层表面裂纹孔洞较多,平均腐蚀失重速率约为0.89 g/(cm2·h)。由此,NaCl浓度越低,耐候钢的自腐蚀电位越正,自腐蚀电流密度越小,腐蚀失重速率越慢。耐候钢在0.1%NaCl浓度的环境中腐蚀1 440 h后其自腐蚀电流密度为105.65μA/mm2,锈层中α-FeOOH与(β-FeOOH+γ-FeOOH)含量的比值接近2,远大于3.5%NaCl浓度时的该比值(0.104),此时锈层状态趋于稳定,并对耐候钢基体具有较好保护作用。Abstract: For the typical bridge weathering steel in practical engineering as the object, the change laws of the surface morphology, phase composition, corrosion weight loss, dynamic curve and electrochemical properties of the rust layer of weathering steel were studied through periodic immersion accelerated corrosion test, and the macro morphology observation method, scanning electron microscope(SEM), X-ray diffraction analysis(XRD) and other methods, The corrosion behavior of Q345qDNH typical weathering steel under simulated industrial marine atmospheric environment NaHSO3 and different NaCl concentrations was investigated.
The results show that the corrosion products on the surface of weathering steel are mainly composed of α-FeOOH, γ-FeOOH, β-FeOOH, Fe2O3, Fe3O4, and the NaCl concentration in the corrosion environment is positively related to the corrosion weight loss rate of weathering steel. When the concentration of NaCl is 0.1%, the corrosion weight loss rate of weathering steel rapidly drops to the low position with the extension of corrosion time and then tends to be stable. After 1 440 h of corrosion, the surface of the rust layer is uniform and dense, and the average corrosion weight loss rate is about 0.76 g/(cm2·h); when the NaCl ion concentration in the corrosion environment is 3.5%, the corrosion weight loss rate of weathering steel is at a high level and increases first and then decreases with the extension of corrosion time. After 1 440 h of corrosion, there are many cracks and holes on the surface of the rust layer, and the average corrosion weight loss rate is about 0.89 g/(cm2·h). Therefore, the lower the NaCl concentration, the more positive the self corrosion potential of weathering steel, the smaller the self corrosion current density and the slower the corrosion weight loss rate. The self corrosion current density of weathering steel is 105.65 μA/mm2 after being corroded for 1 440 h in the environment with 0.1%NaCl concentration, in the rust layer α-FeOOH/(β-FeOOH+γ-FeOOH) ratio is close to 2, much higher than 0.104 in 3.5%NaCl concentration. At this time, the state of rust layer tends to be stable, and it has a good protection effect on weathering steel matrix. -
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