交流杂散电流对地下金属设备腐蚀的影响

Effect of Alternating Current Stray Current on the Corrosion of Underground Metal Equipment

为了解决交流杂散电流对地下设备的腐蚀问题,为变电站接地网腐蚀防护提供依据。通过外加1.2 V,50 Hz的交流电流,在模拟的某变电站pH值=4的酸性土壤溶液中,测试了Q235钢的极化曲线、电位电流-时间曲线和腐蚀速率,分析了交流杂散电流对变电站接地网的腐蚀影响。结果表明:在交流电的正半周期,交流电加速了Q235钢的腐蚀;在交流电的负半周期,Q235钢接地体受到析氢的腐蚀。在模拟条件下测试7天,外加1.2 V,50 Hz交流电时试样经4次90°弯折后脆断;未加交流电时试样经6次90°弯折才出现裂纹。交流杂散电流使试样的腐蚀速度增加了18.8%。

To protect underground metal equipment against corrosion by alternating current(AC)stray current and provide a basis for corrosion protection of substation grounding grid.The polarization curve,potential and current curves with time and corrosion rate of Q235 steel were studied by applying AC current(1.2V,50 Hz)in a simulated acid soil solution of a substation with pH=4.The effect of AC stray current on the corrosion of substation grounding grid was analyzed.The results showed that the corrosion of Q235 steel was accelerated by AC in the positive half cycle.The corrosion behavior of Q235 steel ground grid was mainly controlled by hydrogen evolution in the negative half cycle.Under 7 days simulated test condition,the tested samples by applying AC current fractured in a brittle manner after 4 times of 90°bend,but began to crack without applying AC current after 6 times.The corrosion rate of Q235 steel by applying AC current increased by 18.8%.