锅炉换热管开裂原因

Reasons for cracking of boiler heat exchange tubes

某锅炉换热管在装配过程中出现裂纹,裂纹位于管板焊接接头的焊缝位置。采用宏观观察、化学成分分析、金相检验、硬度测试、扫描电镜分析等方法对该换热管开裂的原因进行分析。结果表明:换热管焊缝中存在未焊透、未熔合、裂纹等焊接缺陷,焊缝热影响区出现淬硬的马氏体,随着装配应力的不断增大,最终换热管发生开裂现象。

Cracks appeared in a certain boiler heat exchange tube during assembly,located at the weld joint position of the tube plate welding joint.The reasons for the cracking of the heat exchange tube were analyzed by macroscopic observation,chemical composition analysis,metallographic examination,hardness testing,scanning electron microscopy analysis.The results show that there were welding defects such as incomplete penetration,incomplete fusion,and cracks in the weld seam of the heat exchange tube.The heat affected zone of the weld seam showed hardened martensite,which eventually led to cracking of the heat exchange tube with increasing assembly stress.