Abstract: Based on the previously proposed rapid annealing method for SPCC steel, the influence of rapid annealing temperature on the relationship among grain size, orientation distribution, and mechanical properties of the SPCC steel was investigated. The results indicate that the rapid annealing temperature is a crucial factor affecting the size of ferrite grains. When the rapid annealing process is conducted at 650 ℃ for 100 s, the tensile strength of the SPCC steel can reach 487.09 MPa, with the elongation after fracture of 26.84% and the product of strength and elongation (PSE) of 13.07 GPa·%. At higher rapid annealing temperature, the grains become coarse, and the favorable {111} texture is enhanced, leading to a significant reduction in strength but a relatively high elongation. Conversely, at lower rapid annealing temperature, due to insufficient ripening of second-phase particles and no significant coarsening of ferrite grains, the material exhibits higher strength but a noticeable decrease in elongation. Furthermore, after grain refinement, the work-hardening ability of the material is diminished, and the {111} texture is weakened. The combined effect of these two factors results in a significant decrease in elongation compared to the traditional annealing methods under rapid annealing. Additionally, within a rapid annealing holding time of 100 s, a higher rapid annealing temperature facilitates a more uniform growth behavior among most ferrite grains, thereby improving the mixed grain structure of ferrite grains.

Key words: SPCC steel, rapid annealing, ferrite, grain size, texture, elongation after fracture