HIP joining of RAFM/RAFM steel and beryllium/RAFM steel for fabrication of the ITER TBM first wall

One of the main research and development issues concerning the test blanket module (TBM) is the development of joining technologies for fabrication of the first wall. The objectives of the present study are to investigate the effects of thermal history corresponding to the TBM fabrication process on reduced activation ferritic martensitic (RAFM) steel microstructure, and to establish the appropriate hot isostatic pressure (HIP) conditions for the fabrication of RAFM/RAFM steels and beryllium (Be)/RAFM steels joints without degradation of the mechanical properties of the RAFM steel or delamination of the joined interface. In this study, RAFM and RAFM steels were joined by HIPing at 1050 °C under 100 MPa for 2 h. During the HIP process, the thermally altered microstructure and mechanical properties were recovered to the as-received state by subsequent normalizing at 950 °C for 2 h and tempering at 750 °C for 2 h. Be and RAFM steels were also bonded successfully by the application of Ti/Cu interlayers and HIPing at 850 °C under 100 MPa for 2 h.