On the cyclic behavior of fusion reactor ferritic-martensitic steels at intermediate temperature

M AVALOS; I ALVAREZ; A ARMAS

MATERIALPRUFUNG

Carl Hanser Verlag

Lugar: Berlin; Año: 2009 vol. 51 p. 376 - 381

0025-5300

The low cycle fatigue response of the ferritic-martensitic steel EUROFER 97 has been investigated at different total plastic strain ranges and temperatures between 20 - 450ºC. The cyclic behaviour has been analyzed through the decomposition of the flow stress in internal and effective stress components and different microstructural mechanisms associated with cyclic softening were proposed to explain the differences observed in those stress components. At 20ºC the cyclic softening could be attributed to a progressively unpinning of dislocations from carbon atoms. At higher temperatures the mechanical softening effects agree with the evolution from initially very fine martensitic laths to a coarser equiaxial cells structure. A decrease of dislocation density inside the micrograins is observed for all the temperatures; in a higher degree for higher temperatures.