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为了确定锅炉过热器管的破裂原因,对破裂的管子进行了宏观和微观分析检查,同时在实验室进行了验证试验。结果指出:过热器管的破损是由氯化物应力腐蚀造成的。过热器运行前的柠檬酸酸洗工艺是造成氯化物应力腐蚀破裂的直接原因,而过热器管表面晶间腐蚀层的存在以及不合理的消除应力退火处理则大大加速了应力腐蚀破裂的产生。此外,在试验基础上还指出了防止酸洗破裂的工艺措施。
In order to determine the cause of the rupture of the boiler superheater tube, the ruptured tube was examined macroscopically and microscopically while the validation test was conducted in the laboratory. The results indicate that damage to superheater tubes is caused by chloride stress corrosion. The citric acid pickling process before superheater operation is the direct cause of chloride stress corrosion cracking, and the presence of intergranular corrosion layer on superheater tube surface and unreasonable stress relief annealing process greatly accelerate the occurrence of stress corrosion cracking. In addition, based on the test also pointed out the technical measures to prevent pickling rupture.