SYMPOSIA PAPER Published: 01 January 2001
STP10564S

Microstructural Evolution of Reduced Activation and Conventional Martensitic Steels after Thermal Aging and Neutron Irradiation

Source

Small-Angle Neutron Scattering (SANS) allows characterization, in a non-destructive way, of the heterogeneities (precipitates, pores, cavities,…) ranging in size between 1 and 100 nm. The SANS technique has been used in order to study the microstructural evolution of martensitic steels under neutron irradiation at 325 °C up to a dose of 0.9 dpa, and after thermal aging between 250°C and 550°C up to 22 000 hours. The investigated materials were Fe-7.5/1 1Cr WVTa Reduced Activation and Fe-9/12Cr MoWV conventional martensitic steels. SANS experiments were coupled with Transmission Electron Microscopy (TEM) observations. The structural information obtained by SANS and TEM is compared with the evolution of mechanical properties. Three main results have been obtained: (1) above 8.8 at.% Cr in solid solution, the ferritic matrix is unstable at an aging temperature of 400°C and separates into a Cr-depleted α and a Cr-rich α′ b.c.c. phase; (2) moreover, a strong radiation-accelerated or induced α′precipitation is observed in alloys irradiated at 325°C; (3) the precipitation of Laves phase Fe2(Mo,W) is strongly dependent on the Mo and W content in the alloys.

Author Information

Mathon, M-H
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
de Carlan, Y
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
Geoffroy, G
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
Averty, X
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
de Novion, C-H
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
Alamo, A
Commissariat à l'Energie Atomique, CEA-Saclay, Gif-sur-Yvette, France
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Details
Developed by Committee: E10
Pages: 674–693
DOI: 10.1520/STP10564S
ISBN-EB: 978-0-8031-5454-4
ISBN-13: 978-0-8031-2878-1