The Performance Differences Between Hot-rolled Steel And Cold-rolled Steel

There are significant differences in performance between hot-rolled steel and cold-rolled steel, mainly manifested in the following aspects:
1. Mechanical properties differences
Strength comparison
Due to the work hardening effect, the yield strength of cold-rolled steel can reach 400-600 MPa, which is 20%-50% higher than that of hot-rolled steel (300-500 MPa).
Plasticity performance
The elongation of hot-rolled steel is usually more than 30% higher than that of cold-rolled steel, making it more suitable for situations requiring large deformation processing (such as stamping, bending)
Toughness indicators
The impact toughness values of hot-rolled steel (such as the V-notch impact test) are generally better than those of cold-rolled steel, especially showing more stability in low-temperature environments.
2. Microstructure characteristics
Crystal grain size
The grain size of hot-rolled steel is approximately 50-100 μm, while that of cold-rolled steel can be refined through deformation to 10-20 μm, but accompanied by an increase in dislocation density.
Residual stress distribution
Hot-rolled steel has a film-like stress distribution, while cold-rolled steel has a curved distribution. The latter improves the load-bearing capacity but is prone to local buckling.
3. Typical failure modes
Hot-rolled steel: Layering defects lead to reduced fatigue life (such as weld zones of bridge steel)
Cold-rolled steel: Work hardening causes brittle fracture (such as edge and corner cracking of automotive stamping parts)