Method of refining chromium-containing steel

A method of refining chromium-containing steel by blowing gas into the molten steel in a refining vessel through a tuyere installed at the bottom of the vessel for decarburization, comprising:

• blowing mixed gas of a non-oxidizing gas and oxygen under atmospheric pressure until the carbon concentration in the molten steel decreases to 0.15% (by weight) or less, and after the carbon concentration decreased below this value, adding a reducing agent in an amount equal to or more of the theoretical amount necessary for reducing chromium oxides in the molten steel, decreasing the pressure in the refining vessel to 150-20 Torr, and using only the non-oxidizing gas as the blown gas in an amount of 0.2-0.5 Nm.sup.3 /min. per ton-steel under vacuum.

A method of refining chromium-containing steel by blowing gas into the molten steel in a refining vessel through a tuyere installed at the bottom of the vessel for decarburization, comprising:

• blowing mixed gas of a non-oxidizing gas and oxygen under atmospheric pressure until the carbon concentration in the molten steel decreases to 0.15% (by weight) or less, and after the carbon concentration decreased below this value, decreasing the pressure in the refining vessel to 150-20 Torr, using only the non-oxidizing gas as the blown gas in an amount of 0.2-0.5 Nm.sup.3 /min. per ton-steel under vacuum, while adding a reducing agent continuously or continually to such amount that the total amount of the reducing agent exceeds the theoretical amount necessary for reducing chromium oxides in the molten steel.

A method of refining chromium-containing steel by blowing gas into the molten steel in a refining vessel through a tuyere installed at the bottom of the vessel for decarburization, comprising:

• blowing mixed gas of a non-oxidizing gas and oxygen under atmospheric pressure until the carbon concentration in the molten steel decreases to 0.15% (by weight) or less, and after the carbon concentration decreased below this value, decreasing the pressure in the refining vessel to 150-20 Torr further blowing a non-oxidizing gas selected from N.sub.2 and the above non-oxidizing gas in an amount of 0.2-0.5 Nm.sup.3 /min. per ton-steel under vacuum, while adding a reducing agent continuously or continually in an amount equal to or more of the amount necessary for reducing chromium oxides in the molten steel.