In a continuous casting method for casting an aluminum-deoxidized molten stainless steel 1 by using a continuous casting apparatus 100 in which a long nozzle 3 extending into a tundish 101 is provided at a ladle 2, the molten stainless steel 1 is poured through the long nozzle 3 into the tundish 101, while immersing a spout 3a into the poured molten stainless steel 1, and the molten stainless steel 1 in the tundish 101 is poured into a casting mold 105. A TD powder 5 is sprayed so that the powder covers the surface of the molten stainless steel 1 in the tundish 101, a nitrogen gas is supplied around the molten stainless steel 1, and a calcium-containing material is added to the molten stainless steel 1 in the tundish 101. The surface of the molten stainless steel 1 after casting is ground.

In a continuous casting method for casting an aluminum-deoxidized molten stainless steel 1 by using a continuous casting apparatus 100 in which a long nozzle 3 extending into a tundish 101 is provided at a ladle 2, the molten stainless steel 1 is poured through the long nozzle 3 into the tundish 101, while immersing a spout 3a into the poured molten stainless steel 1, and the molten stainless steel 1 in the tundish 101 is poured into a casting mold 105. A TD powder 5 is sprayed so that the powder covers the surface of the molten stainless steel 1 in the tundish 101, a nitrogen gas is supplied around the molten stainless steel 1, and a calcium-containing material is added to the molten stainless steel 1 in the tundish 101. The surface of the molten stainless steel 1 after casting is ground.

Improved casting powders and improved casting slags enable production of steels having high aluminum contents of greater than or equal to 1% by weight and, in some cases, high manganese content of greater than or equal to 15% by weight. In some examples, such steels may also or alternatively include greater than or equal to 0.2% by weight titanium. The casting slag may result from a casting powder that comprises CaO and Al.sub.2O.sub.3 components essentially in the form of prefused calcium aluminate. Methods for casting steel, including methods for continuously casting steel, are also disclosed based on the use of the disclosed casting powders or casting slags.

Improved casting powders and improved casting slags enable production of steels having high aluminum contents of greater than or equal to 1% by weight and, in some cases, high manganese content of greater than or equal to 15% by weight. In some examples, such steels may also or alternatively include greater than or equal to 0.2% by weight titanium. The casting slag may result from a casting powder that comprises CaO and Al.sub.2O.sub.3 components essentially in the form of prefused calcium aluminate. Methods for casting steel, including methods for continuously casting steel, are also disclosed based on the use of the disclosed casting powders or casting slags.

In a continuous casting device 100 for casting a stainless steel billet 3c, a long nozzle 2 extending into a tundish 101 is provided at a ladle 1. A molten stainless steel 3 is poured through the long nozzle 2 into the tundish 101, and a spout 2a of the long nozzle 2 is immersed into the poured molten stainless steel 3. During pouring, an argon gas 4a is supplied around the molten stainless steel 3 in the tundish 101. Further, continuous casting is performed, in which, while immersing the spout 2a of the long nozzle 2 into the molten stainless steel 3 in the tundish 101, the molten stainless steel 3 is poured from the ladle 1 into the tundish 101 and poured from the tundish 101 into a casting mold 105. During casting, a nitrogen gas 4b is supplied instead of the argon gas 4a around the molten stainless steel 3 inside the tundish 101.

In a continuous casting device 100 for casting a stainless steel billet 3c, a long nozzle 2 extending into a tundish 101 is provided at a ladle 1. A molten stainless steel 3 is poured through the long nozzle 2 into the tundish 101, and a spout 2a of the long nozzle 2 is immersed into the poured molten stainless steel 3. During pouring, an argon gas 4a is supplied around the molten stainless steel 3 in the tundish 101. Further, continuous casting is performed, in which, while immersing the spout 2a of the long nozzle 2 into the molten stainless steel 3 in the tundish 101, the molten stainless steel 3 is poured from the ladle 1 into the tundish 101 and poured from the tundish 101 into a casting mold 105. During casting, a nitrogen gas 4b is supplied instead of the argon gas 4a around the molten stainless steel 3 inside the tundish 101.

A mold flux is used in continuous casting of Ti-containing hypo-peritectic steel so as to prevent longitudinal cracks from forming on a surface of a slab. The mold flux contains CaO, SiO.sub.2, an alkali metal oxide and a fluorine compound as major components. f(1), f(2) and f(3), which are calculated from the initial chemical composition, are (1.10.5T) to (1.90.5T), 0.05 to 0.40 and 0 to 0.40, respectively, if the Ti content of the molten steel (mass %) is T. The TiO.sub.2 content in the melting state during the casting is no more than 20 mass % and the ratio of the first peak height of perovskite to the first peak height of cuspidine in the mold flux film is no more than 1.0.

A fluoride-free continuous casting mold flux for ultralow carbon steel, comprising the following components in weight percentage: 3-10% of Na.sub.2O, 0-3% of Li.sub.2O, 3-8% of MgO, 5-15% of MnO, 0-8% of BaO, 4-12% of Al.sub.2O.sub.3, and impurities with a content of no more than 2%, the balance being CaO and SiO.sub.2, wherein the ratio of CaO/SiO.sub.2 is 0.8-1.3; the raw materials are mixed and then pre-melted; the pre-melted mold flux requires micro-adjusting according to the component deviation, and the ratio of the pre-melted material is not lower than 70%; then a carbonaceous material of 1-3% by the total weight of the mold flux is added and mixed so as to obtain the finished product mold flux. Said mold flux has a melting point of 1100-1200 C. and a viscosity of 0.2-0.6 Pa.Math.s at 1300 C. A method for preparing a mold flux comprising the following steps: mixing raw materials, pre-melting to obtain a pre-melt; then continuously supplementing raw materials into the pre-melt to obtain a substrate with a desired composition; then adding a carbonaceous material to the substrate and mixing so as to obtain said mold flux. This mold flux is a boron-free and fluoride-free mold flux, can effectively reduce the inclusion defect of blank casting and increase the yield of blank casting.

A fluoride-free continuous casting mold flux for ultralow carbon steel, comprising the following components in weight percentage: 3-10% of Na.sub.2O, 0-3% of Li.sub.2O, 3-8% of MgO, 5-15% of MnO, 0-8% of BaO, 4-12% of Al.sub.2O.sub.3, and impurities with a content of no more than 2%, the balance being CaO and SiO.sub.2, wherein the ratio of CaO/SiO.sub.2 is 0.8-1.3; the raw materials are mixed and then pre-melted; the pre-melted mold flux requires micro-adjusting according to the component deviation, and the ratio of the pre-melted material is not lower than 70%; then a carbonaceous material of 1-3% by the total weight of the mold flux is added and mixed so as to obtain the finished product mold flux. Said mold flux has a melting point of 1100-1200 C. and a viscosity of 0.2-0.6 Pa.Math.s at 1300 C. A method for preparing a mold flux comprising the following steps: mixing raw materials, pre-melting to obtain a pre-melt; then continuously supplementing raw materials into the pre-melt to obtain a substrate with a desired composition; then adding a carbonaceous material to the substrate and mixing so as to obtain said mold flux. This mold flux is a boron-free and fluoride-free mold flux, can effectively reduce the inclusion defect of blank casting and increase the yield of blank casting.