Integrated effect of thermal ageing and low flux irradiation on microstructural evolution of the ferrite of welded austenitic stainless steels

JOURNAL OF NUCLEAR MATERIALS

卷:551

Article

Lindgren, K.¹  Bjurman, M.^2,3  Efsing, P.^2,4  Thuvander, M.¹ 

[1] Chalmers Univ Technol, Gothenburg, Sweden

[2] Royal Inst Technol KTH, Stockholm, Sweden

[3] Studsvik Nucl AB, Nykoping, Sweden

[4] Ringhals AB, Varobacka, Sweden

关键词: Spinodal decomposition;    Thermal aging;    G-phase;    Atom probe tomography;    Neutron irradiation;    Austenitic welds;    Delta ferrite;   

DOI  :  10.1016/j.jnucmat.2021.152967

来源: Elsevier

【 摘 要 】

With the purpose to quantify microstructural changes with respect to ageing degradation, the microstructure of aged type 308 stainless steel welds with a ferrite content of 5-7% has been analysed using atom probe tomography. The weld metal of the core barrel of a decommissioned light water reactor, irradiated during operation of the reactor to 0.1 dpa, 1 dpa and 2 dpa at 280-285 ?C (231,0 0 0 h), are compared to two similar thermally aged welds. In the ferrite of the irradiated welds, there is spinodal decomposition into Cr-rich ?? and Fe-rich ?, with a similar degree of decomposition for all investigated doses, amplitudes of 21-26% and wavelengths between 6 and 9 nm. The ferrite of the thermally aged material showed evidence of decomposition when aged at 325 ?C (an amplitude of 13-14% and wavelength of 5 nm), but not when aged at 291 ?C, thus the irradiation significantly increases the rate of spinodal decomposition. There is G-phase (Ni 16 Si 7 Mn 6 ) precipitation in the ferrite of all the weld metals except the one that was thermally aged at the lowest temperature. After irradiation to 1 and 2 dpa, the G-phase is considerably more well developed than after 0.1 dpa or thermal ageing. (c)& nbsp;2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license ( http://creativecommons.org/licenses/by/4.0/ )

【 授权许可】

Free