埋地热力管线材Q235钢在北京土壤模拟液中的腐蚀行为

Corrosion Behavior of Underground Heat-Supply Pipeline Steel in Simulated Solution of Soil at Different Locations of Beijing City

埋地热力管线材Q235钢在不同土壤中的腐蚀行为不同,为了埋管工程的正确选材、施工,减少埋地热力管线的腐蚀,模拟了北京市城市公共绿地、居民区、桥梁下以及城市主干道绿化带4种土壤溶液,采用电化学测试、扫描电镜(SEM)、能谱分析仪(EDS)及浸泡失重法研究了Q235钢在4种土壤模拟液中的腐蚀行为。结果表明:Q235钢在城市公共绿地土壤和居民区土壤模拟液中以全面腐蚀为主,在桥梁下土壤和城市主干道绿化带土壤模拟液中发生严重点蚀;Q235钢在4种土壤模拟溶中的平均腐蚀速率大小为桥梁下土壤>城市主干道绿化带土壤>居民区土壤>城市公共绿土壤;随着Q235钢在4种土壤模拟液中浸泡时间的延长,富集在其表面的腐蚀产物和结晶盐对腐蚀具有一定的减缓作用,吸附在其表面的Ca2+形成的产物层有效地减缓了Q235钢在城市主干道绿化带土壤模拟液中的腐蚀。

Four kinds of simulated solution of soil of urban pubic green space,residential space,space under bridges and green belts of city main roads in Beijing were prepared.The corrosion behavior of Q235 steel in the simulated soil solution was evaluated based on electrochemical tests,scanning electron microscopic observation,energy dispersive spectrometric analysis and weight loss tests.It was found that Q235 steel was dominated by general corrosion in the simulated solution of soil of urban pubic green space and residential space.However,it was dominated by serious pitting corrosion in the simulated solution of soil of space under bridges and green belts of city main roads.The corrosion rate of Q235 steel in various simulated soil solution declined in an order of simulated solution of soil of space under bridges > simulated solution of soil of green belts of city main roads > simulated solution of soil of residential space > simulated solution of soil of urban pubic green space.When the immersion time was extended,corrosion products and deposited crystallite salts on the surface of Q235 steel could contribute to inhibit the corrosion to some extent.Meanwhile,absorbed layers of Ca 2 + were formed on Q235 steel surface to provide effective corrosion protection for Q235 steel in the simulated solution of soil of green belts of city main roads.