Fabrication of W/FMS joint mock-ups using a hot isostatic pressing

Blocks of tungsten and ferritic–martensitic steel (FMS) were joined without any interfacial defects or cracks. For the joining, two times of a hot isostatic pressing (HIP) were performed. The first HIP (900 °C, 100 MPa, 1.5 h) facilitates the diffusion bonding between W and FMS. The second HIP (750 °C, 70 MPa, 2 h) corresponds to a tempering process to retain the mechanical properties of the FMS. As an interlayer material, titanium foil that can mitigate the thermal expansion difference between W and FMS was used. In addition, a molybdenum foil was inserted to prevent an unwanted bonding of W to a canning material. The lateral cracks in W plates, which were usually observed in the case of a conventional HIP process, were not observed when the molybdenum separator was used. W/FMS joint mock-ups with a dimension of 50 mm × 50 mm × 32 mm (T) were successfully fabricated. The shear strength of the joints was 89 MPa on average.