Elements of a fracture mechanics concept for the cleavage fracture behaviour of RAFM steels using local fracture criteria - final report for task TW1-TTMS-005/D3

Abstract

An effort is made within the European Fusion Technology Programme framework to obtain a fracture mechanics description of the material behaviour in the ductile to brittle transition-regime using local fracture criteria. This report summarizes the necessary procedural steps towards the development of an according design code scheme. It makes heavy use of available code schemes such as the British Energy R6-Code or the ESIS P6 procedure and specializes in application to the class of low activation materials that are envisaged for TIER. Through an integrated approach using a numerical stress analysis at experimentally observed fracture loads of notched tensile specimens, a statistical evaluation of cleavage fracture parameters can be performed. The report contains a description of the necessary steps for the experimental characterization and the numerical analysis as well as results for the two RAFM steel variants F82Hmod and EUROFER 97 which serve as basis for the verification of the method. Statistical inference methods are addressed as well as fractographic investigations that are essential for the verification of the approach via numerical prediction of the fracture origin distribution. Limits of the current methodology are given and topics of future research are indicated.