Corrosion Behaviors of Mo-containing Low Alloy Steels Exposed in Simulated Acidic Marine Atmosphere Environment
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摘要: 采用周期浸润腐蚀实验模拟酸性海洋大气环境，通过失重实验、电化学实验、扫描电镜及能谱、X射线衍射光谱等分析含Mo低合金钢的腐蚀行为和耐蚀机理。结果表明：Mo质量分数为0.2%、0.4%、0.6%、0.8%、1.0%低合金钢的显微组织包含铁素体和珠光体，腐蚀前期Mo含量较少（0.2%~0.8%）的低合金钢的腐蚀产物没有出现明显分层，腐蚀中后期所有试样开始出现明显的分层；含Mo低合金钢的锈层厚度随着时间的延长而变厚，其中Mo含量为0.4%钢材的内锈层较为致密，与基体的裂缝较小，锈层保护性较好；5种含Mo低合金钢的腐蚀速率随着周浸时间的增长整体呈先上升后下降的趋势；当Mo含量为0.2%~0.4%时，对改善耐蚀性的作用影响较大，Mo含量为0.6%~1.0%时，对改善耐蚀性的作用影响较小，该结果与锈层分析、失重测试的结果一致。Abstract: The periodic immersion corrosion experiment was adopted to simulate the acidic marine atmosphere environment. The corrosion behavior and corrosion resistance mechanism of Mo-containing low alloy steels were analyzed by weight loss experiment, electrochemical experiment, scanning electron microscopy, energy disperse spectroscopy and X-ray diffraction spectroscopy. The results showed that the microstructures of low alloy steels with Mo mass fraction of 0.2%, 0.4%, 0.6%, 0.8% and 1.0% were composed of ferrite and pearlite. In the early stage of corrosion, the corrosion products of low alloy steels did not show obvious delamination when Mo content was 0.2%~0.8%, and all samples showed obvious delamination in the middle and late corrosion periods. The rust layer became thicker with the increase of immersion time, and when Mo content was 0.4%, the inner rust layer could provide better protection with relatively denser layer and smaller cracks to the substrate. The corrosion rates of the 5 low alloy steels increased first and then decreased with the increase of immersion time. When Mo content was between 0.2% to 0.4%, it could improve the corrosion resistance performance, while when Mo content was beween 0.6% to 1.0%, it had a small influence on enhancing the corrosion resistance, which was consistent with the results of rust layer analysis and weight loss test.
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