A Study on the Strength of Candidate Materials for Nuclear Fusion Reactor and Their Electron Beam Welded Joint at Cryogenic Temperature

Tensile test of base metal and electron beam welded joint of some aluminum alloys (A7N01, A5083, A6061) and a ferritic special steel (JFMS) was conducted at cryogenic temperature. These materials are candidate materials for nuclear fusion reactor in Japan. Testing temperatures were 293K, 77K and 4.2K. Main testing results obtained are as follows: 1. Most aluminum alloys and their welded joint exhibit serration in the tensile test at 4.2K. 2. Base metal and welded joint of A5083-0 alloy exhibit comparatively high strength and high ductility at cryogenic temperature. 3. Welded joint of A6061-T4 alloy and A7N01-T6 alloy exhibits relatively low ductility at cryogenic temperature compaired with base metal. 4. Base metal of JFMS exhibits brittleness at 77K. Welded joint of this steel exhibits high notch brittleness at the temperature between 293K and 77K.