Strength of a circumferential W/Cu/CuCrZr joint of ITER monoblock

A newly developed methodology for testing ITER monoblock was applied for the first time to measure the strength of a circumferential W/Cu/CuCrZr joint. An innovative anchor-shape configuration was used to machine tensile samples using ITER-specification W/Cu monoblocks, on which ITER-specification CuCrZr pipe was attached using hot radial pressing.

This contribution presents the results of mechanical testing and microstructural investigations of the abovementioned W/Cu/CuCrZr joints conducted at room temperature, as well as at the ITER operational conditions. It is found that depending on the test temperature, the fracture occurs in different locations corresponding to different damage modes. In some cases, the obtained ultimate tensile strength can be directly associated with the joint strength. However, the methodology emphasises the importance of correlating fracture location and detailed microstructural analysis of the fracture surface with the tensile test results. The findings reveal the dependencies of the joint strength and fracture mode on temperature, with a transition in failure modes observed at elevated temperatures. The results presented in this article are important for the interpretation of the effect of future neutron irradiation campaigns on W/Cu/CuCrZr joints.