The effect and mechanism of closed double equal channel angular pressing deformation on He plus irradiation damage of low activation steel

作者：Li, Ping; Dai, Jiren; Wang, Lusheng; Zhou, Yufeng; Wang, Zhaoyu; Xue, Kemin^*

来源：Fusion Engineering and Design, 2023, 187: 113358.

DOI：10.1016/j.fusengdes.2022.113358

• Low activation steel
• Closed double equal channel angular pressing
• He plus irradiation
• Precipitation phases

As the preferred structural material for the cladding first wall of future fusion reactor, improving radiation tolerance of low activation steel is a key problem to ensure nuclear safety. Here we used Closed Double Equal Channel Angular Pressing to produce ultra-fine grain low activation steel and performed He+ irradiation at 500 degrees C on initial and ultrafine-grained low activation steel. It was found that the martensite lath and precipitated phases were effectively refined after deformation. The ultrafine-grained low activation steel reduced the size and density of He bubbles, defect-clusters and dislocation loops generated by irradiation. Deformation created high angle boundaries and facilitated the precipitation of the precipitation phases, leading to increase defect sinks, which consequently enhance the radiation tolerance of low activation steel. Furthermore, since irradiation -induced defects tend to be distributed along the boundaries, the ultra-fine grain structure facilitates the ho-mogenization of irradiation damage. This provides a new reference for the design of irradiation-resistant low activation steel.