低合金结构钢腐蚀的影响因素及其耐蚀性判据

通过对不同厂家或产线生产的相近成分和显微组织的8种低合金工程结构钢样品进行中性盐雾加速腐蚀试验，结合成分测试、微观组织分析、腐蚀产物分析及数据统计与计算拟合等方法，提出了评价低合金结构钢耐蚀性的综合耐蚀指数及其包含钢材成分、夹杂物、组织及晶粒度等多因素的数学表达式。研究结果表明，低合金工程结构钢的耐蚀性除与传统的耐蚀指数I相关外，还受钢中夹杂物、显微组织、晶粒度等多种材料因素的耦合影响，其影响程度按从大到小排序依次为耐蚀合金元素所决定的耐蚀指数I、夹杂物总量、珠光体含量和晶粒度级别。综合耐蚀指数Y可作为比耐蚀指数I指数更有效的低合金钢耐蚀性判据，具有重要的工程应用价值。 

Influence factors and corrosion resistance criterion of low-alloy structural steel

Low-alloy engineering structural steel is widely used in many fields, because of its good mechanical and processing properties. The corrosion resistance of low-alloy engineering structural steel is related not only to chemical composition but also to microstructure, inclusions, grain size, and other factors. However, at present, the direct and fast criterion for evaluating the corrosion resistance of low-alloy structural steel, i.e., the corrosion resistance index I, in the ASTM Standard and China National Standards only involves the chemical composition of low-alloy structural steel and ignores the microstructure, inclusions, and grain size. In the literature on the corrosion resistance of low-alloy structural steel, the coupled effect of chemical composition and other material factors on corrosion resistance and the quantitative analysis of each factor have not been reported. Therefore, a new corrosion resistance index for low-alloy structural steel that includes more factors needs to be proposed. Through the neutral salt spray accelerated corrosion test of eight kinds of low-alloy engineering structural steels with similar composition and microstructure produced by different manufacturers or production lines, combined with the methods of composition test, microstructure analysis, corrosion product analysis, data statistics, and calculation fitting, a composite corrosion resistance index Y for low-alloy structural steel was proposed, and a quantitative index formula containing several factors, including chemical composition, inclusions, microstructure, and grain size, was established. Results show that the corrosion resistance of low-alloy structural steel is affected by the coupling of many material factors, not only the traditional corrosion resistance index I but also inclusions, microstructure, and grain size. The degree of influence is in the order of corrosion resistance index I determined by corrosion-resistant alloy elements, total inclusions, pearlite content, and grain size. The composite corrosion resistance index can be used as an effective criterion for the corrosion resistance of low-alloy structural steel and is of significance in engineering applications.