Ladle Refining

Quality control and chemical composition control during the manufacturing process

(1) Narrow width control of main chemical components

Ladle refining offers control of the chemical compositions in a narrower range than before, and the variation in the mechanical properties of the steel can be small with stable hardenability.

	Ladle refining narrow range control	Applicable upper limit
C	±0.01％	≦0.55
Si	±0.02％	≦0.50
Mn	±0.03％	≦0.90
Mn	±0.04％	0.91 to 1.50
Cr	±0.02％	≦1.20
Mo	±0.01％	≦0.50

(Example) Variation in Jominy value of SCM 415

(2) Impurity reduction

Ultralow P, S steels (≦ 0.005%) and ultralow Ti (≦ 10 ppm) can be manufactured with a combination of hot metal pretreatment, converter blowing and ladle refining, which is effective in improving the fatigue characteristics of products.

Impurity reduction Chart

(3) Reduction of gas composition (oxygen, nitrogen)

For steel requiring high cleanliness, ultralow oxygen steel (≦ 7 ppm) with reduced oxygen in steel can be manufactured by ladle refining. In addition, nitrogen that greatly affects the mechanical properties of steel can be reduced, leading to improved machinability and the reduction of streak flaws.

(Example) Oxygen content of SUJ-2 n = 29 charge Chart

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