含铈重轨钢珠光体组织对抗大气腐蚀的影响

Effect of Pearlite Structure of Cerium-Containing Heavy Rail Steel on Atmospheric Corrosion

通过向重轨钢中添加Ce来改变重轨钢组织,研究其组织对抗大气腐蚀的影响。用中频感应炉冶炼实验用U71Mn,轧制后空冷。SEM测量了实验钢的珠光体片层距,在浓度为(1.0±0.05)×10^(-2)mol·L^(-1)的NaHSO_(3)溶液中模拟了工业大气环境下实验钢的腐蚀,利用热力学计算、失重率、SEM、XRD和电化学方法研究了珠光体组织对抗大气腐蚀的影响。经过热力学计算,含Ce的U71Mn在1600~800℃析出的主要物相Ce_(2)O_(2)S,从而减少了MnS的析出,减少了钢中的有害夹杂析出。随着Ce加入量的增加,U71Mn钢珠光体片层间距先减小后增加,在40×10^(-6)时珠光体片层间距达到最小值0.2480μm。随着腐蚀周期的增加,失重量增加,在腐蚀的后期失重速率基本恒定,失重与时间呈线性关系,斜率分别为1.3755,1.0008,1.3396 g·(m^(2)·h)^(-1)。加入40×10^(-6)Ce和加入80×10^(-6)Ce相比与不含Ce的U71Mn钢耐腐蚀性能分别提升了12.50%和10.4%。电化学实验分别加入铈0,40×10-6,80×10^(-6)的三个样品在第五周期的电流分别为1.93×10^(-4),3.71×10^(-9),2.01×10^(-7)A。XRD物相半定量分析三组样品的稳定产物和不稳定产物的比值分别为0.670,1.625,1.110。对腐蚀样品的表面形貌进行分析,在腐蚀样品的表面均为花状γ-FeOOH,加入40×10^(-6)Ce的晶粒最大,不含Ce的U71Mn钢最小,加入80×10^(-6)Ce居中。

The impact of its structure against atmospheric corrosion was studied by adding Ce to the heavy railsteel to change the structure of the heavy rail steel.The U71 Mn was used for smelting experiments in an intermediate frequency induction furnace,and air-cooled after rolling.The lamella spacing of the experimental steel wasmeasured by SEM.The corrosion of the experimental steel in an industrial atmosphere was simulated in a NaH-SO_(3) solution with a concentration of(1.0±0.05)×10^(-2) mol·L^(-1).Thermodynamic calculation,weight loss rate,SEM,XRD and electrochemical methods were used to study the effect of pearlite on anti-atmospheric corrosion.After thermodynamic calculations,the main phase Ce_(2)O_(2)S was precipitated from Ce-containing U71 Mn at 1600~800℃,thereby reduced the precipitation of Mn S and reduced the harmful inclusion precipitation in steel.Withthe increase of Ce addition amount,the interlayer spacing of U71 Mn steel pearlite decreases first and then in-creases.At 40×10^(-6),the interlayer spacing of pearlite reaches the minimum value of 0.2480μm.As the corro-sion cycle increases,the weight loss increases.In the later period of the corrosion,the weight loss rate is basi-cally constant,and has a linear relationship with time.The slopes are 1.3755,1.0008 and 1.3396 g·(m^(2)·h)^(-1).Compared with the addition of 40×10^(-6) Ce and the addition of 80×10^(-6) Ce,the corrosion resistance of U71 Mnsteel without Ce increased by 12.50% and 10.4%,respectively.In the electrochemical experiment,the currentsof the three groups of samples added with 0,40×10^(-6),and 80×10^(-6) of cerium in the fifth cycle were 1.93×10^(-4),3.71×10^(-9) and 2.01×10^(-7) A,respectively.XRD phase semi-quantitative analysis of the ratios of stable and unsta-ble products in the three groups of samples were 0.670,1.625,and 1.11,respectively.For the analysis of thesurface morphology of the corroded samples,the surface of the corroded samples are all flower-shaped γ-FeOOH,the grains with the addition of 40×10^(-6) Ce are the largest,the smallest are the U71 Mn steel withoutCe,and 80×10^(-6) Ce is the middle.