Effects of phosphorus impurity on the microstructure and impact toughness of weld joint for the 12Cr2Mo1R heat resistant steel

Abstract

Abstract A shielded metal arc welding (SMAW) process was used to join the 12Cr2Mo1R heat resistant steel plates in a butt configuration with R407C welding electrode. The microstructure of weld metal was examined by using the optical microscope, the morphology of the cracking and the propagation zones of the impact fracture surface were observed by the scanning electron microscopy. The small island-like M-A phases were found on the ferrite matrix, which composed by martensite and retained austenite with irregular shapes. With the increase of phosphorus impurity, the brittleness of weld metal increased and the impact toughness was sensitive to phosphorus impurity. The phosphorus impurity in the R407C welding electrode can change the fracture morphology of the weld joint.