1. Normalizing (most recommended & common)
Process: Heat to 910–950 °C, hold, then air cool slowly.
Effect:
Refines ferrite grains uniformly
Eliminates rolling segregation & banded structure
Reduces internal stress
Greatly raises impact energy and lowers brittle transition temperature
Advantage: No loss of corrosion resistance; standard for improved low‑temp grade.
2. Fine-grain controlled normalizing / normalized rolling
Combine controlled hot rolling + normalizing
Produces ultra-fine microstructure
Further boosts toughness without losing strength.
3. Stress-relief annealing (auxiliary improvement)
Process: 600–640 °C, slow cool
Effect: Removes residual stress from cutting/welding, improves toughness in welded parts
Not a main treatment, but helpful for finished components.
Treatments NOT suitable for S355J0WP
Quenching + tempering: Makes strength too high, reduces ductility, risks brittleness and destroys balanced weathering alloy system.
High-temperature annealing: Causes grain coarsening, worsens low‑temperature toughness.
