Abstract: A heat exchanger produced by a company. The tube medium of the heat exchanger is temperature-controlled water, and the shell medium is low-pressure steam. The heat exchange equipment suddenly leaked in less than half a year, causing the equipment to stop. During the maintenance inspection, cracks were found at the tube head of the heat exchange tube, and the cracks were circumferential cracks, and some tubes even broke. Therefore,the chemical composition, hardness, mechanical properties and metallographic structure of the heat transfer tubes were tested and analyzed. The micro-morphology of the crack was observed and analyzed by SEM, and the product of the heat exchange tube fracture was analyzed by EDS spectrometer. The results show that the inclusion is part of the cause of the cracking of heat exchange tube, and the corrosive medium in the heat exchange tube is an important cause of the failure of heat exchange tube. The excessive internal stress in the heat exchange tube is the root cause of the failure of the heat exchange tubes.

Key words: Heat transfer tube, Failure analysis, Corrosion, Internal stress

摘要： 某公司生产的一种换热器，其管程介质为调温水，壳程介质为低压蒸汽。换热设备在运行不到半年突然发生泄漏事故，导致设备停车。维修检查时发现多处换热管的管头处存在裂纹，且裂纹为环向裂纹，有的管头甚至出现断裂现象。为此，对换热管的化学成分、硬度、力学性能、金相组织进行了检测和分析，用SEM扫描电镜对裂纹的微观形貌进行观察和分析，同时用EDS能谱仪对换热管断口处的产物进行分析。结果表明，夹杂物是引起换热管开裂的部分原因，换热管中的腐蚀介质是导致换热管失效的重要原因，换热管中内应力过大是引起换热管失效的根本原因。

关键词: 换热管, 失效分析, 腐蚀, 内应力