Impact properties at cryogenic temperature of candicate materials for fusion reactor and their electron beam welded joints are investigated by using instrumented Charpy impact testing apparatus. Material used are aluminum alloys (A7N01, A5083, A6061), JFMS (Japanese Ferritic Martensitic Steel) and two kinds of high manganese steels. Although JFMS is a steel for high temperature use, the impact test is conducted at low tenperature same as the cases of the other materials. Testing results are obtained as follows.
1. Base metals and welded joints of aluminum alloys exhibit high absorbed energy at low temperature. Ductility of each base metal and welded joint gradually decreases with decreasing of testing temperature.
2. Base metal and welded joint of JFMS exhibit an absorved energy transition temperature at near a room temperature.
3. Base metal and welded joint of high manganese)steel A-T (18Mn) exhibit abrupt decreasing of absorbed energy at 77K, but base metal and welded joint of high manganese steel B-T (22Mn-0.2N) exhibit gradual increasing of maximum strength and decreasing of ductility with decreasing of testing temperature.
