Effect of cold rolling reduction rate and softening annealing on the microstructure evolution and properties of DT4C cold-rolled strip

This study establishes an innovative two-step annealing process to resolve the longstanding trade-off between stamping formability and magnetic properties in sub-2.0 mm DT4C cold-rolled strips. Systematic investigation of cold rolling reduction rates (55–80%) and softening annealing reveals: (1) Reduction-driven texture control: Higher reduction rates (57–77%) intensify γ-fiber texture ({111}) but degrade post-annealing magnetic properties. (2) Process innovation: The proposed sequence—cold rolling → softening annealing (800°C) → stamping → magnetic annealing (900°C)—decouples microstructure evolution. Softening annealing yields fine equiaxed grains (21.5–30.8 μm) with dominant γ-fiber texture (87–108 HV), ensuring stamping formability. Subsequent magnetic annealing enhances Goss texture ({110} <001>, peak intensity 13.56 at 71% reduction) while suppressing γ-fiber. (3) Breakthrough performance: At 71% reduction, two-step annealing achieves H c = 15 A/m (53–63% reduction vs. conventional one-step) and B 10000 = 1.865 T (0.8–1.4% gain), exceeding super electromagnetic pure iron standards ( H c ≤ 32 A/m, B 10000 > 1.83 T). This industrially scalable strategy enables concurrent high stamping formability and magnetic performance for energy-efficient transformers and magnetic shields.