P91管道焊缝异常组织检验与分析

Inspection and Analysis of Abnormal Microstructure of P91 Pipe Welding Seam

对某350MW超临界循环流化床锅炉的P91材质主蒸汽管道和再热热段管道的焊缝进行了金相检验,发现了白块及网状组织,对白块组织进行了能谱分析,发现白块组织不是通常的δ铁素体,而是纯Cr块,形成的原因是焊接过程中熔池搅动不充分或药皮脱落;网状组织分为白色网状组织和黑色网状组织,形成的原因是在盖面焊接过程中焊接能量过大,导致焊缝过热造成的。

The microstructure of the weld in P91 main steam piping and hot reheater steam pipe of a 350 MW supercritical circulating fluidized bed boiler was tested. The white block structure and network structure were found in the weld.The white block structure was analyzed by EDS. It is founded that the white block structure is not δ ferrite but is pure Cr, which resulted from insufficiency stirring of the weld pool or falling off of the coating. The network microstructure was divided into white network and black network structures. The reason of network structure formation is that the welding energy in cosmetic welding is too large resulting in overheating in the weld.