稀土Ce对DH36船板钢显微组织及耐腐蚀性能的影响研究

Study on the Effect of Rare Earth Ce on Microstructure and Corrosion Resistance of DH36 Ship Plate Steel

针对稀土对钢耐腐蚀性的影响规律及稀土夹杂对船板钢的局部腐蚀机理的研究不足,采用金相显微镜、扫描电子显微镜、激光共聚焦显微镜、电化学工作站研究了在3.5%NaCl溶液中稀土Ce含量对DH36船板钢显微组织和耐腐蚀性能的影响。结果表明,稀土Ce可以细化试验钢的晶粒尺寸,同时降低试验钢的珠光体片层间距。稀土Ce的加入将试验钢中的MnS和Al_(2)O_(3)+MnS夹杂转变为MnS+CeAlO_(3)、Mn-Al-O-Ce、Mn-S-Al-O-Ce夹杂。相比于未添加Ce和添加0.001 0%Ce的试验钢而言,Ce含量为0.009 2%时试验钢的腐蚀速率最低,团絮状腐蚀产物最少,腐蚀坑的尺寸与数量最小,表面粗糙程度较小,且初期仍具有金属光泽;稀土Ce的加入使得试验钢的腐蚀电位升高,腐蚀电流密度降低。腐蚀时间为5 d时,Ce含量为0.009 2%时试验钢的腐蚀电流密度最低(2.225×10^(-5 )A/cm^(2)),腐蚀电压最高(-1.057 V),耐腐蚀性能最佳。

In response to the insufficient research on the influence law of rare earth on the corrosion resis-tance of steel and the local corrosion mechanism of rare earth inclusions on ship plate steel,the influence of rare earth Ce content on the microstructure and corrosion resistance of DH36 ship plate steel in a 3.5% NaCl solution was studied using metallographic microscope,scanning electron microscope,laser confocal microscope,and electrochemical workstation.The results indicate that rare earth Ce can refine the grain size of the test steel and reduce the interlayer spacing of pearlite in the test steel.The addition of rare earth Ce transforms the MnS and Al_(2)O_(3)+MnS inclusions in the test steel into MnS+CeAlO_(3),Mn-Al-O-Ce and Mn-S-Al-O-Ce inclusions.Compared with the test steel without Ce and with 0.001 0% Ce,the corrosion rate of the test steel with 0.009 2% Ce is the lowest,the flocculent corrosion products are the least,the size and number of corrosion pits are the smallest,the surface roughness is relatively small,and it still has a metallic luster in the initial stage.The addition of rare earth Ce increases the corrosion potential and reduces the corrosion current density of the test steel.When the corrosion time is 5 d,the corrosion current density of the test steel with 0.009 2% Ce is the lowest(2.225 × 10^(-5) A/cm~2),the corrosion voltage is the highest(-1.057 V),and the corrosion resistance performance is the best.