Microstructure and tensile behavior of powder metallurgy FeCrAl accident tolerant fuel cladding
Shenyan Huang, Evan J. Dolley, Ke An, Dunji Yu, Cole Crawford, Michelle A. Othon, Ian Spinelli, Mike P. Knussman, Raúl B. Rebak
Abstract
Defect-free seamless FeCrAl cladding tubes with 0.3 mm wall thickness have been successfully developed via full-scale powder metallurgy (PM) manufacturing routes, providing a cost neutral replacement of Zircaloy-2 tubes with enhanced accident tolerant fuel. Microstructure and tensile properties at room temperature and 315 °C were evaluated in the tubing of two yttrium-free FeCrAl alloy compositions PM-C26M and Ferritic Alloy – Sandvik Material Technology (FA-SMT) that differ in Cr, Al, Mo and minor addition of refractory elements. The powder metallurgy FeCrAl tubes reveal finer grain size than the smallest achievable grain size by cast/wrought tube fabrication process, low retained strain, and tensile properties superior to Zircaloy-2 cladding tubes. <101> fiber texture along the tube axial direction was observed. In-situ neutron diffraction during tensile loading shows qualitatively similar trend of intergranular load transfer during elastoplastic deformation in PM-C26M and FA-SMT, while FA-SMT indicates higher dislocation density and PM-C26M reveals more intensive <101> texture evolution along loading direction. Precipitates in FA-SMT are inferred to share load from the matrix, while such load sharing is not evident in PM-C26M. Compared to texture free ferritic steel data in the literature, the <101> fiber texture in the FeCrAl tubes seems to have little effect on the grain-level tensile deformation behavior including elastic anisotropy and plastic anisotropy.