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2014
ACL
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J.Chen, P.Jung, T.Rebac, F.Duval, T.Sauvage, Y.de Carlan, M.F.Barthe, 'Helium effects on creep properties of Fe–14CrWTi ODS steel at 650 °C', J. Nucl. Mater. 453 253-258 (2014) doi:10.1016/j.jnucmat.2014.07.010
In the present paper, the effects of helium on creep properties of Fe–14CrWTi ODS steel were studied by
in-beam and post He-implantation creep tests. In-situ creep was performed in an in-beam creep device
under uniaxial tensile stresses from 350 to 370 MPa during homogeneous helium implantation. Helium
ions of energies varying from 0 to 25 MeV were implanted at a rate of 6 103 appm/s (corresponding to
a displacement dose rate of 1.5 106 dpa/s). The average temperature was controlled to 650 C within
±2 C. In addition, post He-implantation creep tests were conducted at 650 C as well. Subsequently,
fracture surfaces and helium bubble evolution were studied in detail by SEM and TEM observations,
respectively. Preliminary creep results show that helium slightly shortens the creep life time of ODS steel
at 650 C. Fracture surfaces of reference as well as implanted specimens, show areas with various grades
of deformation. Areas of highest deformation can be interpreted as necking, while areas of low deformation
show in helium implanted specimens a more granular structure. The results are discussed in terms of
possible embrittlement of ODS steels by helium.
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