Effect of welding parameters on fracture resistance characteristics of nuclear piping

To guarantee the safety of nuclear power plants during operation and maintain coolant pipe integrity during life time, the evaluation of the coolant pipe integrity is necessary. The welded part is the most vulnerable place for the crack initiation and subsequent growth. Moreover, the weld width and the crack location also affected the deformation and fracture behavior of the welded part. Therefore, the evaluation of the welded part integrity in the coolant pipe while considering the residual stresses and welding defects is very important. In recent years, FE analysis about the welded parts in a pipe has been performed to evaluate the fracture toughness characteristics for the welded parts with various welding parameters. However, test method has not been proposed to evaluate the fracture toughness properties of the welded parts in a pipe. In this study, piping materials which are equivalent to those in safety injection pipes of nuclear power plants were welded to form a butt welding part. Then, fracture toughness tests for base metal, the similar and the dissimilar welded parts were performed to evaluate the effect of welding parameters.