Effect of Continuous Annealing Temperature on Microstructure and Properties of Ultra-Purified Ferritic Stainless Steel

Abstract

Effect of continuous annealing temperature on mechanical properties, formability, work hardening rate, texture, and corrosion resistance of ultra-purified ferritic stainless steel is analyzed by means of tensile test, electron back scattering diffraction, and electrochemical tests. The results show that with the increase of continuous annealing temperature during 850–940 °C, tensile strength and yield strength of the tested steel reduce and then rise slightly and decrease at last. Elongation increases sharply with the rise of continuous annealing temperature and then kept approximately constant. At 910 °C, the best formability and comprehensive performance are obtained, and the strength and elongation achieve best comprehensive performance. The grains near the {111} orientation grow up selectively. The higher continuous annealing temperature, the more obvious the tendency of growing and thus the more the γ fiber texture content. The low energy and low ∑ CSL grain boundaries composed of textures are the reasons why the corrosion resistance of specimen presents the changing trend similar to texture orientation. With the increases of continuous annealing temperature, the passive potential range and the stability of the surface film first increase and then decrease, while the pitting corrosion potential first decrease slightly and then increase sharply.