Beryllium/ferritic martensitic steel joining for the fabrication of the ITER test blanket module first wall

The first wall of an international thermonuclear experimental reactor (ITER) test blanket module (TBM) is a multilayered component consisting of plasma facing armor and structural materials including the cooling channels. One of the main issues about the R&D on the TBM is to develop the joining technologies for a fabrication of the TBM first wall. The objectives of this study are to optimize the hot isostatic pressing (HIP) conditions and the interlayer combination for the fabrication of beryllium (Be)/ferritic martensitic steel (FMS) joints without a degradation of the mechanical properties of the FMS. Effects of HIP joining conditions including the temperature and interlayer types were investigated. The HIP temperature was selected for the anticipated tempering condition for FMS to avoid a grain coarsening which would deteriorate the mechanical properties of FMS. Several interlayer materials were applied in order to manufacture high strength joints. Be and FMS were joined successfully by the application of a Ti/Cu interlayer and it showed a relatively high bending strength, 257 MPa, among the interlayer types studied. The fracture was caused by a delamination of the reaction layer between FMS and the coated interlayer without a plastic deformation. This paper summarizes the results of a Be/FMS joints manufacturing and an investigation of their properties.