Abstract: Effect of annealing temperature on microstructure, mechanical properties, formability, and microtexture of the 21Cr-0.3Cu ultra-pure ferrite stainless steel was studied by means of optical microscope, tensile testing and backscattered electron diffraction. The results show that when the tested steel is annealed at 970 ℃, the grains are fine and uniform, and the structure is in a completely recrystallized state. When the annealing temperature is lower than 970 ℃, the recrystallization is incomplete; while when higher than 970 ℃, the recrystallized grains grow abnormally, and mixed grain microstructure appears in both the cases. When the tested steel is annealed at 970 ℃, the overall mechanical properties are the best, with a tensile strength of 473 MPa, a yield strength of 315 MPa, and an elongation of 35.7%. As the annealing temperature rises, the average plastic strain ratio r_m first increases then decreases, getting the maximum value of 1.82 at 800 ℃. The change trend of the γ texture density is consistent with that of the value of average plastic strain ratio r_m. When the annealing temperature is 970 ℃, the γ texture is reinforced obviously. At this time, its orientation density reaches the maximum value f(g)=20.56, and the forming performance is the best.

Key words: ferritic stainless steel, average plastic strain ratio, annealing temperature, texture, formability