Nanoindentation creep behavior of RPV’s weld joint at room temperature
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SA508 Gr.3 steel has been widely used in nuclear reactor pressure vessels (RPV). Nuclear components are generally combined through arc welding processes, which always produces heterogeneous mechanical properties in heat affected zone (HAZ) of weld joint. In order to study mechanical heterogeneity of weld joint, HAZ was been divided into five small regions (HAZ1 to HAZ5) based on the distance from the weld center line. The elastic modulus, hardness, and creep deformations of five regions in HAZ were measured through nanoindentation, as well as base and weld metals. According to the experimental results, the HAZ2 region (belonging to the fine-grained HAZ) exhibited a significantly lower hardness and creep behavior. Strain rate sensitivities (SRS) in different regions were then estimated from the steady-state creep, and the HAZ2 region showed a relatively higher value. The influence of grain boundary fraction on the creep behavior of weld joints was discussed later. Furthermore, the results of SRS also indicated that the creep mechanism of tested regions could be dominated by dislocation activities.
KeywordsWeld joints Nanoindentation Creep Strain rate sensitivity
The research work was supported by the National 13th five-year Key Technologies R&D Program (No. 2016YFC0801902), National Natural Science Foundation of China (51575489 and 11502235) and Zhejiang Provincial Natural Science Foundation of China (LY18E010006).
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