耐酸性土壤接地网用低合金钢及其腐蚀行为研究

发布时间：2019-01-05 01:51

【摘要】：基于模拟土壤腐蚀模型,建立了土壤孔隙度、含水量、含盐量以及pH值与腐蚀电流密度间的函数关系,分析表明：试样腐蚀电流密度随土壤孔隙度的增大而减小,随土壤含水量的增大先增大后减小,随土壤含盐量的增大先增大后趋于稳定,随土壤pH值的降低而增大。为快速评价设计材料的耐酸性土壤腐蚀能力,建立了硅藻土模拟土壤腐蚀评价方法,模拟土壤单因素试验结果与腐蚀模型预测趋势具有良好的吻合关系。以此为基础,提出了硅藻土粗细比4：6、含水量35%,pH值4.5,盐含量放大5倍的模拟土壤A。模拟土壤与实际土壤中Q235钢的腐蚀行为对比研究表明,模拟土壤具有良好的模拟性和加速性,在不改变腐蚀机理的前提下,最高加速比可达5倍。 为解决接地网用钢腐蚀问题,基于多种软件工具集成计算并初步提出了耐酸性土壤腐蚀接地网用低合金钢设计思路。分别采用HSC Chemistry6、 JmatPro、Thermo-Calc软件分析了钢中C、Cr、Si口Mn元素对其耐蚀性、导电性、热熔点的影响规律：钢中添加适量的Cr可以有效抑制金属铁的阳极溶解,扩大材料的钝化区；随C、Cr和Si含量的增加,钢的电阻率升高,熔点降低;钢中Mn含量变化对钢的电阻率和熔点影响不大。基于材料综合性能的集成计算结果,提出了C含量≤0.1%,Cr含量1.0-2.0%,Si含量≤0.1%,其他元素适量的合金设计思路,采用高洁净度冶金工艺炼制了低碳Cr合金化A1钢和超低碳Cr合金化A2钢。性能测试结果表明：A1钢电阻率较Q235钢增加了0.07μΩ·m,熔点降低了13℃,其导电性和热稳定性未明显恶化；A2钢的电阻率较Q235钢降低了0.014μΩ·m,熔点增加了15℃,具有良好的导电性和热稳定性。 以模拟土壤A为腐蚀介质,通过腐蚀失重、SEM、XRD、XPS和电化学测试等方法,研究了实验钢在模拟土壤中的腐蚀行为及腐蚀机理。结果表明：高洁净度冶金工艺降低了钢中夹杂物等级,减少了点蚀诱发源数量；低碳设计消除了传统碳钢中铁素体与珠光体组织微电池腐蚀；钢中添加的Cr可以提高钢的腐蚀电位,降低点蚀发生敏感性,并随腐蚀发展以Fe2CrO4的形态富集于内锈层,促进钢中超细晶α-(Fe1-x, Crx)OOH的形成,提高了锈层的致密性和保护能力。腐蚀末期A1和A2钢的腐蚀速率为0.45mm/a、0.38mm/a,其耐蚀性分别较Q235钢提高了30%和50%。
[Abstract]:Based on the simulated soil corrosion model, the functional relationship between soil porosity, water content, salt content, pH value and corrosion current density is established. The results show that the corrosion current density decreases with the increase of soil porosity. With the increase of soil moisture content, the soil water content increased first, then decreased, and then stabilized with the increase of soil salt content, and increased with the decrease of soil pH value. In order to quickly evaluate the corrosion resistance of the design materials, a method of simulating soil corrosion by diatomite was established. The results of simulated soil single factor test were in good agreement with the corrosion model prediction trend. On the basis of this, the simulated soil with diatomite aspect ratio of 4: 6, water content of 35% and pH value of 4.5 and salt content of 5 times were proposed. The corrosion behavior of Q235 steel in simulated soil is compared with that in real soil. The results show that the simulated soil has good simulation and acceleration, and the maximum acceleration ratio can reach 5 times without changing the corrosion mechanism. In order to solve the problem of steel corrosion in grounding grid, the design idea of low alloy steel for grounding grid for acid resistant soil corrosion is put forward based on the integrated calculation of various software tools. The effects of Mn elements on corrosion resistance, electrical conductivity and hot melting point were analyzed by HSC Chemistry6, JmatPro,Thermo-Calc software. The addition of appropriate amount of Cr in steel can effectively inhibit the anodic dissolution of iron. Expanding the passivation zone of the material; With the increase of Cr and Si content, the resistivity of steel increases and the melting point decreases, and the change of Mn content in steel has little effect on the resistivity and melting point of steel. Based on the results of the integrated calculation of the comprehensive properties of the materials, the design idea of alloy with C content 鈮，

本文编号：2401102