In the as-rolled or as-forged condition, the microstructure is non-uniform, consisting of coarse, often banded ferrite-pearlite structures from the high-temperature finish. Properties are:
Variable and Non-Guaranteed throughout the cross-section.
Lower Strength and Toughness compared to the quenched & tempered state.
Poor Machinability (can be gummy) in some cases.
Further heat treatment (Normalizing or Quenching & Tempering) is necessary to:
Refine the grain structure.
Homogenize the microstructure and chemistry.
Achieve the guaranteed, reproducible, and optimal mechanical properties required for engineering design.
The as-rolled state is merely an intermediate processing step.