Nucor Corporation

Eugene B Pretorius

Walter N Blejde

Mark Schlichting

David John Sosinsky

David W McGaughey

Jacobus Marthinus Andreas Geldenhuis

Daniel Gene Murray

Rama Ballay Mahapatra

David Wayne Mcgaughey

A method of making a steel with low carbon less than 0.035% by weight including steps of preparing a heat of molten steel composition in a steelmaking furnace to a tapping temperature as desired for desulfurization at a VTD, tapping open into a ladle the molten steel composition with an oxygen level between about 600 and 1120 ppm, providing slag forming compound to the ladle to form a slag cover over the molten steel composition in the ladle, transporting the molten steel composition in the ladle to a VTD, decarburizing the molten steel composition at the VTD by drawing a vacuum of less than 650 millibars, after decarburizing, adding one or more deoxidizers to the molten steel composition and deoxidizing the molten steel composition, after deoxidizing, adding one or more flux compounds to desulfurize the molten steel composition, and casting the molten steel composition to form a steel with low carbon less than 0.035% by weight.

Low cost making of a low carbon, low sulfur, and low nitrogen steel using conventional steelmaking equipment

A method of and apparatus for continuous casting of thin cast strip including removing oxides from the casting surface of each casting roll by contacting the casting surface of each casting roll with a rotating brush between the nip and the casting area, determining the temperature in segments along the casting roll surfaces or across the cast strip adjacent the nip, and delivering gas adjacent the casting surface between the rotating cleaning brush and the casting area regulated in segments corresponding to the determined temperature in the segment to control the quality of the strip produced. The gas delivery adjacent the casting surface between the rotating brush and the casting area may be done in at least five segments along the casting roll, and the temperature determination step may be done in a continuum such as by a scanning pyrometer. The temperature determination of the cast strip may be done between 0.2 and 1 meter from the nip.

Method and apparatus for localized control of heat flux in thin cast strip

A method of forming and refining molten silicon-bearing steel by addition of a calcium-containing silicon additive. Determine if the amount of calcium in the calcium-containing silicon additive is more or less than the amount of calcium desired in the finished steel. If it is more than the amount of calcium desired in the finished steel, add the amount of calcium-containing silicon additive corresponding to the excess calcium early during steel deoxidation or in refining to combine with oxygen, sulfur and other impurities in refining, and add the calcium-containing silicon additive containing the total amount of calcium desired in the finished steel after the desulfurization of the molten steel and before casting. If the amount of calcium in the calcium-containing silicon additive does not provide the total amount of calcium desired in the finished steel, adding an additional amount of calcium after desulfurization of the molten steel and before casting to the molten steel during refining.

Refinement of steel

A method of and apparatus for localized control of heat flux in continuous casting of thin cast strip comprising removing oxides from the casting surface of each casting roll by contacting the casting surface of each casting roll with the rotating brush in advance of the casting area, and delivering gas at the casting surface between the rotating brush and entry to the casting area to form a gas layer on the casting surface of each casting roll where the oxides have been removed. The delivering of gas at the casting surface between the rotating brush and entry to the casting area is preferably done in at least three zones along the casting roll axes to form a gas layer on the casting surface of each casting roll where the oxides have been removed, where the gas projected in the respective zones can be of different composition, mixture, pressure, or combination thereof.

A method of casting steel strip by introducing molten plain carbon steel on casting surfaces at least one casting roll with the molten steel having a free nitrogen content below 120 ppm and a free hydrogen content below about 6.5 ppm measured at atmospheric pressure. The free nitrogen content maybe below about 100 ppm or below about 85 ppm. The free hydrogen content maybe between 1.0 and 6.5 ppm at atmospheric pressure. Novel cast strip of plain carbon steel is produced having a strip thickness less than 5 mm or less than 2 mm by use of the method.

Growing community of inventors

Mt. Pleasant, SC, United States of America

Eugene B Pretorius