Solidification microstructure control of homogeneous and fine-grained FeCrAl alloy tube based on hypergravity casting

Abstract

FeCrAl alloys exhibit exceptional high-temperature resistance to oxidation and corrosion resistance, which makes them widely applicable as cladding materials in nuclear reactors. As-cast FeCrAl alloys are prepared by electric arc melting or vacuum induction melting. However, these conventional melting methods often result in coarse grains, with large columnar grains forming along the cooling direction, leading to anisotropic properties and difficulties in subsequent processing and forming. To address these issues, a novel solidification-controlled hypergravity casting method has been proposed. By introducing it innovatively in the preparation of FeCrAl alloys, a structure with a high proportion of equiaxed grains and good mechanical properties was successfully obtained without altering the chemical composition or introducing secondary phase strengthening. Furthermore, Procast numerical simulation was employed to systematically reveal the intrinsic relationships between melt flow, heat transfer, temperature field variations, and microstructure evolution. Experimental results indicate that the FeCrAl alloy optimized using the proposed method exhibits a finer and more uniform microstructure, with a 111 % increase in plasticity and a 14.85 % increase in tensile strength compared to the vertical centrifugal casting process. These results deepen the understanding of the properties of as-cast FeCrAl alloys and provide a solid theoretical basis for practical engineering applications.