高强耐蚀钢筋在氯盐环境下的腐蚀行为

发布时间：2018-10-22 15:16

【摘要】：近年来,随着我国经济现代化建设步伐的加快,对钢铁材料在高强度以及耐蚀性能等方面提出了一定的要求。本文以耐候钢和普碳钢作为试验对象,利用电化学方法分析评价了试验材料的腐蚀行为;采用周浸和盐雾对试验钢进行实验室加速腐蚀试验,探讨成分对氯盐环境下的腐蚀规律;利用扫描电镜和XRD衍射仪,对不同加速腐蚀情况下的锈层形貌与结构进行测定。对试验钢电化学的研究结果表明:当钢中Cr含量超过0.7%时,在3.5%Na Cl溶液中动电位极化时,阳极出现“钝化”现象,并且随着Cr含量的增加,其维钝电位范围逐渐增大,且其维钝电流密度逐渐减小。钢中加入Cr、Ni等元素时,其自腐蚀电位总体偏高,随着Cr、Ni、Cu、Mn等含量的加入,钢发生腐蚀的倾向性越小;钢的纯净度越高,也即钢中S、O等含量越低,其腐蚀电流密度越小,也即钢发生腐蚀的速率越慢。另外,随着Mn含量的增加,在腐蚀后期,Mn-Cu的协同作用改善了锈层结构,增强了锈层与基体的结合强度,改进了锈层的离子选择性,从而降低腐蚀后期腐蚀速率。对试验钢的周浸腐蚀试验研究结果表明:随着钢中C含量的减少,Cr、Ni、Cu、Mn含量的增加,其腐蚀速率明显减小;合金元素的添加使锈层结构得到了改善,内锈层中的裂纹与孔洞减少,锈层致密增厚,且与基体的结合强度提高;合金元素的协同作用抑制了β-Fe OOH的生成、促使锈的非晶化和更多γ-Fe OOH、Fe3O4的生成,改善了锈的组成,从而提高耐蚀性能。对试验钢的盐雾腐蚀试验研究结果表明:钢中加入Cr、Ni、Cu、Mn等合金元素,在蚀坑处富集形成难溶物质使合金耐腐蚀性得以提升。锈层耐蚀性与锈层结构密切相关,在腐蚀初期,锈层中γ-Fe OOH衍射强度较高,α-Fe OOH衍射强度较低,因此其腐蚀速率在刚开始时总体上呈现上升趋势;在腐蚀后期,γ-Fe OOH逐渐转化为α-Fe OOH,γ-Fe OOH逐渐消失,α-Fe OOH/γ-Fe OOH比值迅速增大,因此腐蚀速率迅速下降。综上所述,本文探讨了合金元素的添加对腐蚀性能的影响规律,为耐蚀钢筋的合金元素设计了提供依据。
[Abstract]:In recent years, with the acceleration of the pace of economic modernization in China, some requirements have been put forward for the high strength and corrosion resistance of iron and steel materials. In this paper, weathering steel and carbon steel are used as test objects, the corrosion behavior of test material is analyzed and evaluated by electrochemical method, and accelerated corrosion test of test steel is carried out by using cycle immersion and salt spray. The corrosion law of the composition in chloride environment was discussed, and the morphology and structure of rust layer under different accelerated corrosion conditions were determined by scanning electron microscope and XRD diffractometer. The electrochemical results of the test steel show that when the content of Cr in the steel exceeds 0.7, the anodic "passivation" occurs when the dynamic potential is polarized in the 3.5%Na Cl solution, and with the increase of the content of Cr, the range of the potential is gradually increased. And the density of blunt current decreases gradually. With the addition of Cr,Ni and other elements, the corrosion potential of steel is generally higher. With the addition of Cr,Ni,Cu,Mn and other elements, the corrosion tendency of steel is smaller, and the purity of steel is higher, that is, the lower the content of Cr,Ni in steel, the smaller the corrosion current density. In other words, the rate of corrosion of steel is slower. In addition, with the increase of Mn content, the synergistic action of Mn-Cu improves the structure of rust layer, enhances the bonding strength between rust layer and substrate, and improves the ion selectivity of rust layer, thus reducing the corrosion rate in late corrosion period. The results show that the corrosion rate of steel decreases with the decrease of C content, the increase of Cr,Ni,Cu,Mn content, the improvement of rust layer structure with the addition of alloying elements, and the decrease of cracks and pores in the inner rust layer. The rust layer is densified and thickened, and the bonding strength with the matrix is increased, and the synergistic effect of alloy elements inhibits the formation of 尾-Fe OOH, promotes the formation of amorphous rust and more 纬-Fe OOH,Fe3O4, improves the composition of rust and improves the corrosion resistance. The results of salt spray corrosion test of the test steel show that the corrosion resistance of the alloy can be improved by adding Cr,Ni,Cu,Mn and other alloy elements in the corrosion pit to form insoluble material. The corrosion resistance of rust layer is closely related to the structure of rust layer. At the beginning of corrosion, the diffraction intensity of 纬-Fe OOH is higher and the diffraction intensity of 伪-Fe OOH is lower in the rusty layer. At the late stage of corrosion, 纬-Fe OOH was gradually transformed into 伪-Fe OOH, 纬-Fe OOH, and the ratio of 伪-Fe OOH/ 纬-Fe OOH increased rapidly, so the corrosion rate decreased rapidly. To sum up, the influence of alloy elements on corrosion resistance is discussed in this paper, which provides a basis for the design of alloy elements of corrosion-resistant steel bars.
【学位授予单位】：安徽工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG172

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