Influence of Cold-Rolling Reduction on Microstructure and Tensile Properties of Nuclear FeCrAl Alloy with Low Cr and Nb Contents

摘要

FeCrAl alloy is one of the most promising candidates as an accident-tolerant fuel(ATF)cladding material.Herein,the influence of cold-rolling(CR)reduction on microstructure and tensile properties of the as-annealed FeCrAl alloys,with low Cr and Nb contents,is systematically examined.With the increase in CR reduction,the grain size of FeCrAl alloy is obviously refined after annealing because the increase in stored deformation energy leads to enhanced recrystallization.However,the large CR reductions result in a severe mixed-grain microstructure,significantly reducing the uniform deformability of the FeCrAl alloy.The dislocation density of the as-annealed FeCrAl alloy decreases with the increase in CR reduction,except for the excessive CR reduction of 50%.Moreover,the Laves phases are crushed and dissolved during CR and annealing,as well as large amounts of refined Laves phases are found after large CR reductions.The pinning effect of the Laves phases can significantly improve the strength of FeCrAl alloy.Accordingly,the strengthening mechanisms of FeCrAl alloy consist of fine-grain strengthening,dislocation strengthening and precipitation strengthening.Finally,the FeCrAl alloy,with a CR reduction of 30%,achieves optimal tensile properties.This study can provide theoretical guidance for the industrial production of the FeCrAl alloy.