Estudio del comportamiento en enfriamiento continuo del acero martensítico ferrítico de activación reducida F82H

AUTOR(ES)
FONTE

Matéria (Rio J.)

DATA DE PUBLICAÇÃO

19/07/2018

RESUMO

ABSTRACT 9% Cr martensitic-ferritic steels are currently the privileged candidates to manufacture structural components of the so-called Generation IV nuclear fission reactors, because they exhibit very good thermophysical and mechanical properties under neutron irradiation. Along with them, the so-called Reduced Activation Ferritic-Martensitic steels (RAFM’s) have been in the same way selected for the future nuclear fusion reactors. In this contribution we introduce results involving the transformation behavior under continuous cooling of the F82H RAFM steel, obtained by applying the differential scanning calorimetry (DSC) technique. The metal-lurgical state of the as-received material was normalized and tempered. The applied thermal cycles were as follows: heating at 5 ºC/min up to 1050 ºC/min (austenite phase field), austenite holding for 15 min. and cooling at fixed rates between 1.5 and 50 ºC/min under constant pressure. After DSC test, samples were pre-pared by conventional techniques to be observed by optical microscopy. An algorithm under Matlab language was satisfactorily developed which allowed the simultaneous determination of the baseline and the transformed fraction as a function of temperature on the basis of a recursive procedure proposed in the previous literature. The transformation to martensite for the F82H steel under the prescribed thermal cycle conditions showed to be strongly dependent on the applied cooling rate, giving rise to a splitting phenomenon -or a multi-step transformation mechanism- as the cooling rate is lowered.

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