Low temperature embrittlement behaviour of different ferritic-martensitic alloys for fusion applications

In the last few years a lot of different low activation Cr-WVTa steels have been developed world-wide. Without irradiation some of these alloys show clearly a better low temperature embrittlement behaviour than commercial Cr-NiMoV(Nb) alloys. Within the MANITU project a study was carried out to compare, prior to the irradiation program, the embrittlement behaviour of different alloys in the unirradiated condition performing instrumented Charpy impact bending tests with sub-size specimens. The low activation materials (LAM) considered were different OPTIFER alloys (Forschungs-zentrum Karlsruhe), F82H (JAERI), 9Cr-2WVTa (ORNL), and GA3X (PNL). The modified commercial 10-11% Cr-NiMoVNb steels were MANET and OPTIMAR. A meaningful comparison between these alloys could be drawn, since the specimens of all materials were manufactured and tested under the same conditions.