Effects of annealing temperature on the microstructure, textures and tensile properties of cold-rolled Fe–13Cr–4Al alloys with different Nb contents

Abstract

In this study, four Fe–13Cr–4Al alloys with different Nb contents (0–1.5 wt%) were prepared by using vacuum induction melting, forging, hot rolling, and cold rolling. The effects of annealing temperature (600 °C–1100 °C) and the Nb contents on the microstructure, textures as well as tensile properties were investigated. The dispersion of fine Fe2Nb-type Laves phase particles was observed in the BCC matrix and along grain boundaries. These particles effectively pinned dislocations and boundaries, resulting in stabilizing the microstructure, delaying the recrystallization temperatures and refining the recrystallized grains. The Laves phase particles were also able to retard the nucleation and growth of the γ fiber grains, therefore Nb-containing alloys had weak recrystallized γ fibers, which was beneficial to improve the processing properties of Fe–13Cr–4Al alloys. As the annealing temperature increased, the strengths decreased while the elongation increased. Because of the effects of solid solution strengthening, precipitation strengthening and fine grain strengthening produced by the addition of Nb element, the strength and hardness of the alloys increased with the increase of Nb content. Comprehensively considering the microstructure and mechanical properties, the suitable addition of Nb content was 1 wt%, and the optimum annealing treatment after cold-rolling with 50% thickness reduction was at 700 °C for 30 min.