表面技术2025，Vol.54Issue(18)：54-64,11.DOI:10.16490/j.cnki.issn.1001-3660.2025.18.006
碱性土壤环境中高强管线钢钝化及点蚀行为
Passivation and Pitting Behavior of High-strength Pipeline Steel in an Alkaline Soil Environment
摘要
Abstract
The third-generation oxide metallurgy technology improves the strength,toughness,hydrogen resistance and other properties of high-strength pipeline steel by regulating the microstructure and modifying inclusions,but it also has a significant impact on the formation of passive films,semiconductor properties and pitting corrosion behavior in alkaline soil environments.In this study,the characteristics of passive films and pitting behaviors of X70 grade pipeline steels treated with Mg,Ca,and Mg-Ca in a simulated alkaline soil solution were investigated by electrochemical methods(e.g.,potentiodynamic scanning,potentiostatic polarization,and Mott-Schottky curves)combined with microscopic analysis techniques(e.g.,XPS,EDS,and pitting morphology observation).The microstructure types,inclusion composition and size in high-strength pipeline steels treated with Mg,Ca and Mg-Ca were characterized,and their correlations with pitting corrosion resistance were discussed,so as to clarify the effects of different treatment methods on the characteristics of passive films and pitting behaviors of high-strength pipeline steels in simulated alkaline soil solutions. The average grain sizes of the samples treated with Mg,Ca,and Mg-Ca were 5.59,9.26,and 3.81 μm,respectively.The proportions of the ferrite phase were 74.0％,73.5％,and 62.3％,and the inclusion densities were 0.098,0.014,and 0.048 particles μm-2.In a solution of 0.01 mol/L NaCl+0.2 mol/L NaHCO3,n-type semiconductor passive films formed on the surfaces of the Mg-treated,Ca-treated,and Mg-Ca-treated samples.The flat-band potentials(Efb)were-0.519,-0.417,and-0.491 V,respectively,the donor densities were 6.126×1021,4.979 ×1021,and 5.889×1021 cm-3,the film resistances(Rf)were 8.14,27.31,and 14.88 kΩ·cm2.The passivation current of the Mg-Ca-treated sample was the lowest at 0.040 μA/cm2,but its pitting potential was the lowest at-0.128 V,and the hysteresis loop area was the largest,reaching 544 μA·V/cm2.In contrast,the Ca-treated sample had the highest Eb and Ep,with the smallest hysteresis loop area,which were-0.082 V,-0.259 V,and 215 μA·V/cm2,respectively. Based on nucleation-growth and point defect models,during the nucleation stage of the passive film,ferrite,due to its simple crystal structure and high reactivity,shows a higher nucleation rate,leading to higher initial polarization current density and pseudocapacitance values in Mg-treated samples.In the growth stage of the passive film,the Ca-treated sample,due to uniformly distributed vacancies in its bainitic structure,accelerates the formation rate of the passive film,allowing it to reach a steady-state current density in a shorter time and form a dense passive film with fewer defects,exhibiting lower donor density and excellent stability.The passive films on the surfaces of Mg-treated,Ca-treated,and Mg-Ca-treated samples all exhibit n-type semiconductor characteristics.The passive film on the Ca-treated sample has a more positive flat-band potential,lower donor density,and higher film resistance and charge transfer resistance,indicating that the passive film can maintain charge balance at higher potentials and demonstrates the best corrosion resistance.Additionally,the passive film on the Ca-treated sample is thicker,and its inclusion density is the lowest,reducing the likelihood of pitting initiation,resulting in the highest pitting potential and lowest pitting density,and exhibiting the strongest pitting resistance.关键词
管线钢/钝化膜/半导体特性/点蚀行为/氧化物冶金Key words
pipeline steel/passive film/semiconductor properties/pitting corrosion behavior/oxide metallurgy分类
矿业与冶金引用本文复制引用
许志昱,胡骞,胡月,黄峰,刘静..碱性土壤环境中高强管线钢钝化及点蚀行为[J].表面技术,2025,54(18):54-64,11.基金项目
湖北省重大科技攻关项目(2023BAA003)Major Program(JD)of Hubei Province(2023BAA003) （2023BAA003）
