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Hot rolling is done above the metal’s recrystallization temperature.
Recrystallization happens when:

• Heat and time are enough during annealing.

• New, stress-free grains replace deformed ones.

• The metal structure changes fully.

This process improves the metal’s properties.
The recrystallization temperature is the average of the temperatures when:

• New grains first form.

• The structure is fully replaced.

It is influenced by:

• Alloy composition

• Amount of deformation

• Original grain size

• Annealing temperature

Kelebihan daripada Hot-Rolled Stainless Steel

1. Lower Energy Use and Cost

• Less force is needed during hot rolling.

• Energy is saved.

• Costs are reduced.

2. Improved Workability

• Coarse grains from casting are broken.

• Cracks and defects are reduced.

• The structure becomes easier to process.

3. Higher Production Efficiency

• Large ingots and heavy reductions are used.

• Rolling speed can be increased.

• Continuous and automated rolling is possible.

Disadvantages of Hot-Rolled Stainless Steel

1. Delamination Risk

• Inclusions (like sulfides, oxides) are flattened.

• Delamination can occur between layers.

• It weakens strength in the thickness direction.

• Weld shrinkage may lead to layer tearing.

2. Residual Stress

• Uneven cooling causes internal stress.

• Stress is balanced inside but not visible.

• It may cause deformation and reduce fatigue life.

• Thicker steel sections often have more stress.

3. Less Precise Mechanical Properties

• Strength is not as high as cold-worked steel.

• Properties are not uniform.

• Plasticity is between cold-worked and annealed steel.

4. Poor Thickness and Surface Control

• Thickness is harder to control.

• Surface is rougher than cold-rolled steel.

• Kekasaran permukaan (Ra) is 0.5–1.5 μm higher.

• Hot-rolled products are often used as billets for cold rolling.