Understanding CR Annealing Routes
The annealing process defines the formability and surface of cold rolled steel. Two main methods are used: batch (bell‑type) annealing and continuous annealing. Each produces different property profiles suitable for different end‑uses.

Batch Annealing (BA)

• Process: Coils are stacked under a hydrogen atmosphere bell and heated slowly to ~680°C, soaked for hours, and cooled slowly.

• Result: Fully recrystallized ferrite with coarse, equiaxed grains. Excellent deep drawability (high r‑value). Surface can be bright (if hydrogen protective) or slightly blued.

• Best For: Deep‑drawing grades SPCE, DC04, DC05.

Continuous Annealing (CAL)

• Process: Strip is rapidly heated to ~800°C, held for 1‑2 minutes, and quenched.

• Result: Finer grain size, higher strength, more uniform properties along the coil length. Surface is uniformly bright.

• Best For: High‑strength CR grades, commercial quality, and tinplate base.

Property Comparison