world of steel A Division of Ellias International

      Posco Manufacturing Process



A) Production Process (at the customer) :-


Production processes differ according to the intended use of the parts. In addition, the heat treatment of the completed parts will determine the quality of the metal. 

Hot rolling ->pickling ->Shearing ->Forming -> Farm tools, chains (S45C) Mainly for low grade uses
heat treatment (quenching and tempering) Shanks (SCM435)
Hot rolling ->pickling ->skelp ->annealing (BAF) ->cold rolling -> Needles Mainly for high greade uses
Annealing (BAF) ->forming ->heat treatment (quenching and tempering) Measuring tape (SK85)
Hot rolling ->shearing ->hot press & mold quenching Impact beams Some processes omitted
Hot rolling ->skelp ->ERW pipe ->heat treatment Automobile door impact beams (AUTOBEAM) Replacement for round bar

*AUTOBEAM: POSCO standard (high-carbon boron steel)

Quenching & Tempering Heat Treatment:-

Heat treatment increases hardness and is consisted of two processes: Quenching (which brings high hardness along with great brittleness) is performed by heating the steel to a high temperature and then cooling it rapidly.
Tempering (which lowers hardness while raising stiffness) is a re-heating process to a proper temperature. The degree of hardness after quenching as well as the hardness and heat treatment depth after tempering must be determined before heat treatment begins. Carbon content, degree of heat treatment, alloy content, and spherodized structure are all factors used in determining hardness.

B) Quality Requirement for Each Process (Quality Control Points):-

Steelmaking-Rolling Pickling Cold Rolling Annealing Parts Productions Q & T Heat Treatment
Chemical Composition
Pickling effectiveness Cold roling efficiency

-Strip breakage
-Loss ratio
Surface decarbonization Blanking efficiency

-Fine blanking


Heat treatability

Sup-pression of ash defects CR thickness tolerance Spheroidization rate Consistent structure and properties
Post heat treatment properties

-TS, EL, hardness
Surface scale
    Hardness after annealing   Final product performance

-Fatigue resistance

-Wear resistance

Property deviations along the longitudinal direction (hardness)
Microstructure control


- Low sulfur content is controlled to prevent internal quality degradation (1/4t, 1/2t lamination) from high-carbon segregation.
- Cr is added to increase wear resistance, prevent surface decarbonization, and improve quenching effectiveness by suppressing pearlite transformation.
- Low soluble aluminum content is maintained to improve quenching effectiveness through austenite growth.