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12Cr13钢热碱泵使用短时间内发生严重变形失效,采用SEM、EDS、XRD等检测技术对失效后叶轮表面腐蚀形貌、腐蚀产物物相及组成进行分析,查找失效原因,采用正交实验对各因素的影响程度进行分析。结果表明:叶轮表面发生严重的冲刷腐蚀,腐蚀产物多孔疏松,分布有少量微裂纹,产物中除了可形成钝化膜的Cr_2O_3也含有Fe,Mg和Zn等的化合物,破坏了Cr2O3钝化膜的连续性和致密性,失去对基材的保护作用;大流速冲刷促进腐蚀产物的剥落,加剧局域性碱腐蚀;冲刷腐蚀造成叶轮明显减薄,降低强度,最终导致变形失效。各因素对12Cr13钢腐蚀速率影响从大到小的顺序为:流速、温度、时间、浓度。
12Cr13 steel thermal alkali pump with a short period of serious deformation failure, the use of SEM, EDS, XRD and other detection techniques on the failure of the impeller surface corrosion morphology, corrosion product phase and composition analysis to find the cause of failure, using orthogonal test The impact of various factors were analyzed. The results show that the surface of the impeller is seriously eroded and the corrosion products are porous and loose with a few microcracks distributed. In addition to the Cr_2O_3 which can form the passivation film, the products also contain Fe, Mg and Zn compounds, which destroy the Cr2O3 passivation film Continuity and compactness, and lose the protective effect on the substrate. The high-velocity scour promotes the exfoliation of the corrosion products and aggravates the localized alkali corrosion. The erosion and erosion causes the impeller to be obviously thinned and the strength is reduced, which eventually leads to deformation failure. The factors affecting the corrosion rate of 12Cr13 steel descending order are: flow rate, temperature, time, concentration.