The fatigue property of 05Cr17Ni4Cu4Nb steel(used for the last stage rotor blade of steam turbine)weld joints was studied by means of four-point-bending fatigue test.Moreover

the S-N curve of the weld joints was obtained and compared with that of the parent material.The results showed that

adopting the optimized weld and post weld heat treatment process

the05Cr17Ni4Cu4Nb steel weld joints' conditional fatigue limit could reach 90%of that of the parent metal.The SEM observation of fracture surface of the fatigue specimen indicated that the microdefect in surface or near surface of the weld joints and the microstructure heterogeneity were the main factors affecting the fatigue property of the 05Cr17Ni4Cu4Nb steel weld joints.Thus

several important measures enhancing fatigue life of the weld joints were put forward

such as strictly controlling the welding procedure

decreasing the weld microstructure defects

and preventing the over growth of crystalline grain in heat affected zone.