In view of the failure trend in early-stage operation of the title steel weld joints

specimens were taken from the high-temperature superheater of a 1025t/h boiler after a practical operation of one overhaul period (about20000h)

and structure property analysis had been carried out thereafter. Through metallurgical structure analysis

α phase observation

intergranular corrosion test

tensile test

and bending test etc.

it was found that the mechanical property of SA213-TP347H+12Cr2MoWVTiB steel weld joint under normal temperature hadn't notable variation after 20000h operation

but the austenitic granular boundary had been in a remarkable sensitive condition

being easily subjected to intergranular corrosion and stress corrosion; At location near weld seam on the side of 12Cr2MoWVTiB

there are notable canals of oxidation

forming easily stress concentration

and bringing out micro root-cracks. Based on the test and analysis

measures for ensuring safe operation of said differen steel weld joints have been put forward.