Insights from Microstructure and Recrystallization Comparisons of Wrought FeCrAl and Oxide Dispersion-Strengthened Nanostructured Ferritic Alloy Tubes

Journal article, 2024

This work aims to compare the microstructure and recrystallization of wrought FeCrAl alloy and oxide dispersion-strengthened nanostructured ferrite alloy (ODS-NFA) in industrial pilgered tubes. The second-phase particles significantly affect the microstructure and recrystallization. The micron-sized Laves precipitates in FeCrAl alloy lead to complete recrystallization at 800 °C. Nano-oxide particles in the ODS-NFA tube stabilize the ultrafine fibrous grains and result in delayed recrystallization at 1200 °C. Hardness measurements and electron backscatter diffraction quantify the recrystallization kinetics, grain size, and texture evolution of both alloys during recrystallization. The recrystallization mechanism of FeCrAl alloy is grain boundaries and Laves precipitates stimulate nucleation, while the recrystallization of ODS-NFA is controlled by nanoparticle dissolution and reprecipitation. Completely recrystallized FeCrAl alloy shows ≈20 μm grains and ODS-NFA shows ≈10 μm equiaxed grains. The FeCrAl alloy exhibits γ-fibers, while the ODS-NFA alloy exhibits strong α-fibers during recrystallization.