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为了进一步提高低合金钢的抗点蚀性能,采用Ti/Al脱氧及Ca处理工艺熔炼并轧制制备了试验钢。利用场发射扫描电镜及能谱仪(SEM-EDS)、电化学极化试验及浸蚀前、后夹杂物的原位观测,研究了不同脱氧工艺钢中夹杂物在模拟海水介质中诱导点蚀的行为。结果表明:与Al脱氧钢相比,Ti脱氧钢中形成了富含Ti Ox、数量更多、尺寸更细小的夹杂物,有利于Mn S的局部分散析出,降低其诱发点蚀的危害,采用Ti脱氧工艺有助于提高钢的抗点蚀性能;Mn S诱发点蚀的能力强于氧化物夹杂,点蚀优先在Mn S夹杂与基体的界面处及夹杂物曲率半径小的区域萌生;降低夹杂物的腐蚀活性应该以调控夹杂物的组成为基础,其次优化夹杂物的形貌(球形化),在微米级范围内,夹杂物尺寸对点蚀诱发的影响最小。
In order to further improve the pitting corrosion resistance of low alloy steels, the test steels were prepared by melting and rolling Ti / Al deoxidation and Ca treatment. The field emission scanning electron microscopy (SEM) and energy dispersive spectroscopy (SEM-EDS), electrochemical polarization test and in situ observation of inclusions before and after etching were used to study the effects of inclusions in different deoxidation process on the simulation of seawater medium the behavior of. The results show that compared with Al deoxidized steels, Ti-rich steels with more Ti oxides and smaller sizes are formed in Ti deoxidized steels, which are favorable for the local dispersion precipitation of Mn S and the reduction of the damage caused by pitting. Ti deoxidation process can help to improve the anti-pitting performance of steel; Mn S ability to induce pitting corrosion stronger than oxide inclusions, pitting priority in the Mn S inclusions and matrix interface and inclusions with small radius of curvature initiation; reduce The corrosion activity of inclusions should be based on the composition of the control inclusions, and secondly to optimize the morphology of the inclusions (spheroidization). In the micrometer range, the inclusion size has the least influence on the pitting induced.