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对刺穿失效的蒸汽发生器炉管对流管段进行了宏观分析、材料及腐蚀产物成分分析、金相分析及扫描电镜分析。分析结果表明,蒸汽发生器炉管失效主要源于向火面一侧的内表面腐蚀。腐蚀产物主要为Fe2O3,表明炉管内存在较为剧烈的汽水腐蚀、氧腐蚀和电解腐蚀;冲蚀和气蚀是导致炉管表面产生裂纹、脱落,不断减薄以至失效的重要原因。研究分析认为,要延长炉管寿命,应从严格进行水处理,选择耐腐蚀的炉管材料,实行腐蚀保护或在线监测等方面着手解决。
The macroscopical analysis, the composition analysis of the materials and corrosion products, the metallographic analysis and the scanning electron microscopy (SEM) were carried out on the convection pipe sections of failed steam generator tubes. The analysis results show that the failure of the steam generator tube mainly comes from the corrosion on the inner surface of the fire surface. The main corrosion products are Fe2O3, which indicates that there is more severe corrosion of soda, oxygen and electrolytic corrosion in the tube. Erosion and cavitation are the main causes of cracking, falling off, thinning and even failure of the tube surface. Research and analysis believe that, to extend the life of the furnace, should be strictly carried out water treatment, corrosion-resistant tube material selection, corrosion protection or on-line monitoring and other aspects to be addressed.