摘要
通过宏观检查、金相检验、拉伸试验对某电厂末级过热器T23爆管原因进行分析。分析结果表明,该管材爆口呈长时过热特征,材质符合标准要求,但金相组织严重老化,爆口附近管段的抗拉强度明显低于ASME标准的技术要求。综上所述,该末级过热器管因长期超温运行,导致其蠕变速度加快,管径胀粗,组织老化,产生蠕变孔洞、蠕变微裂纹,微裂纹逐步扩展,最后导致整个管材断裂。
Through the macroscopic examination,metallographic examination,tensile test,the causes of the T23 tube burst of final superheater of a power plant are analyzed.The analysis results show that the burst of the tube is characterized by long overheating and material compliance with the standard requirements,but the metallurgical structure is seriously aging.The tensile strength of the tube section near the burst is obviously lower than that of the ASME standard.To sum up,the final superheater tube is running over temperature for a long time,resulting in its accelerated creep speed,dilated tube diameter and aging,resulting in creep holes,creep microcracks,and gradual expansion of micro cracks,leading to fracture of the whole tube.
关键词
末级过热器
金相组织
抗拉强度
蠕变微裂纹
final superheater tube
metallographic structure
tensile strength
creep microcrack
