Torsion test technique for interfacial shear evaluation of F82H RAFM HIP-joints

A hot isostatic press (HIP) process is a key technology to fabricate a first wall with cooling channels of the blanket system utilizing a reduced-activation ferritic/martensitic (RAFM) steel such as F82H. A primary objective of this study is to characterize interfacial properties of HIPed F82H joints by torsion to identify the feasibility of this test method for the inspection of the HIPed F82H joints. It is apparent that the absorption energies of the HIP joints varied by the processing conditions, although the maximum shear strength was not much different. The fracture surface observation study indicated that the reduction of the absorption energy obtained in the torsion tests was primarily due to the oxide formed on the interface of the HIP joint. Of particular importance, these features were very consistent with the results of Charpy impact tests. Preliminary test results then suggest that the torsion test method with a miniature specimen has a potential to evaluate the shear properties of the HIPed joint interface.