Thermal fatigue on steels for ITER and DEMO

C PETERSEN; I ALVAREZ; A ARMAS

San Petesburgo, Rusia

Conferencia; 2nd Int Conf on the Effect of Irradiation on Materials of Fusion; 1992

Engineering Materials Advisory Services LTD

In first wall structures of fusion reactors like ITER high dose radiation will be an important issue. At present thermal cycling is considered, beside the radiation damage, as the most detrimental lifetime limiting phenomenon for the above structure. A test method for performing uniaxial low cycle thermal fatigue tests on metals is described. The tubular specimens are thermally cycled between a fixed low temperature (200°C) and a variable high temperature (550°C to 750°C) in air atmosphere. Total mechanical strain amplitudes between 0.4% and 1.4% are evaluated in case of AISI 316L and between 0.3% and 0.5% in case of ferritic-martensitic steel. Thermal fatigue life, of both steels examined, is found to be shorter than isothermal, strain controlled fatigue life at a temperature equal to the high temperature of thermal cycling. Crack initiation occured in most cases on nonmetallic inclusions or impurities. Dislocations are of a well defined cell configuration, occupying the largest volume fraction in the deformed area of the specimen