FRACTURE-TOUGHNESS OF CANDIDATE MATERIALS FOR ITER FIRST WALL, BLANKET, AND SHIELD STRUCTURES

Although the design of the International Thermonuclear Experimental Re actor is still in an evolutionary phase, the most probable choice for a structural material is a 300 series austenitic stainless steel. An e xperiment was carried out in the High Flux Isotope Reactor to quantify the effects of neutron irradiation on the fracture toughness properti es of a range of austenitic stainless steels. The alloys investigated were provided by programs in the European Community, United States, an d Japan; they included 316, 316L, and titanium-stabilized steels in co ld-worked, annealed, and welded conditions. Subsize disk compact tensi on specimens were irradiated to a dose of about 3 dpa and 50 appm heli um (the expected fusion value) at temperatures of either 60 to 125 deg rees C or 200 to 300 degrees C. With the exception of a cold-worked ai r-melted heat of 316, all materials retained excellent fracture toughn ess, with K-J values varying from 150 to 400 MPa root m over the test temperature range from 90 to 250 degrees C.