稀土Ce对低碳微合金钢耐腐蚀性能的影响

Effect of Rare Earth Ce on Corrosion Resistance of Low-Carbon Microalloyed Steel

为了提高低碳微合金钢在海洋环境中的耐腐蚀性能,采用金相显微镜、SEM、EBSD、电化学分析等测试手段研究了不同稀土Ce含量的试验钢在3.5%NaCl溶液模拟的海洋环境中的腐蚀行为。结果表明:试验钢的显微组织主要由铁素体和珠光体组成,稀土Ce可以细化晶粒,减小夹杂物的尺寸,将试验钢中Al_(2)O_(3)、MnS、Al_(2)O_(3)+MnS夹杂物改性为MnS+CeAlO_(3)、Ce_(2)O_(3)夹杂物,并且改性后的夹杂物应力明显降低,减小了微孔洞、裂纹萌生的概率。另外,稀土Ce的加入可以降低试验钢的腐蚀电流密度,提高腐蚀电压,使得腐蚀产物中γ-FeOOH的含量减少,同时α-FeOOH和Fe_(3)O_(4)含量增多,可降低反应活性,提高锈层对基体的保护作用。因此,相对于未添加稀土Ce的低碳微合金钢,添加稀土Ce的低碳微合金钢表现出更好的耐海水腐蚀性能。

To improve the corrosion resistance of low-carbon microalloyed steel in marine environments,the corrosion behavior of the test steel with different cerium(Ce)contents in a marine environment simulated with 3.5%NaCl solution was studied by employing metallographic microscope,SEM,EBSD,and electrochemical analysis.The results show that the microstructure of the test steel mainly consists of ferrite and pearlite.Ce can refine the grains,reduce the size of inclusions,and modify the Al_(2)O_(3),MnS,and Al_(2)O_(3)+MnS inclusions in the test steel into MnS+CeAlO_(3) and Ce_(2)O_(3).The modified inclusions significantly reduce the stress,thereby decreasing the probability of micropore and crack initiation.Additionally,the addition of Ce can decrease the corrosion current density of the test steel,increase the corrosion potential,reduce the content ofγ-FeOOH in the corrosion products,and increase the content ofα-FeOOH and Fe_(3)O_(4),lowering the reaction activity and enhancing the protective effect of the rust layer on the substrate.Therefore,compared with low-carbon microalloyed steel without Ce addition,the low-carbon microalloyed steel with Ce addition exhibits better seawater corrosion resistance.