高温过热器管道开裂原因分析

Analysis on the reason of the high temperature superheater tube cracking

某电厂用高温过热器管道,其端部与它管的对接采用焊接方式,使用约半个月后,在对接焊缝处发生开裂。借助光学显微镜、扫描电镜(SEM)、能谱(EDS)等手段对管道材质,裂纹形态及扩展方式,以及断口表面进行分析。结果表明:该电厂用高温过热器管道由于焊后热处理工艺不当,从而导致焊接残余应力存在,因此,管道在使用过程中会受到环境介质及使用温度的共同作用从而导致管道开裂。

The superheater tube used in a certain power plant,the butt joint between the end of which and other tube was welded,cracking occured in the welded seam after using about half a month.The tube material,the morphology and propagation of the crack and fracture surface were analyzed by using optical microscope（OM）,scanning electron microscope（SEM）,and energy dispersive spectrum（EDS）.The results show that improper heat treatment process leads to welding residual stress.Interaction of welding residual stress,the environmental media and operating temperature results in cracking of tube.