Creep-Fatigue Fracture of Dissimilar Metal Electron Beam Welded Joints at Elevated Temperature

Creep-fatigue tests of dissimilar-metal electron beam welded joints between A387 Gr.22 ferritic low-alloy steel and AISI 405 ferritic stainless steel were carried out under strain-controlled cycling at a temperature of 873 K. It was found that the creep-fatigue life of a dissimilar metal welded joint was significantly shorter than those of its base metals. This resulted from the strain concentration on the AISI 405 side (with the lower deformation resistance.) It was also found that the hardness distribution was one of the important measures by which the local strain distribution was reflected. Furthermore, a simple prediction method for the creep-fatigue life of dissimilar metal welded joints was proposed based on the creep-fatigue life properties of its base metals by applying the strain range partitioning approach. The predicted lives were in good agreement with the experimental results.