High-manganese high-nitrogen low-nickel stainless steel plate blank continuous casting crystallizer covering slag and preparation method thereof

Abstract

The invention discloses high-manganese high-nitrogen low-nickel stainless steel plate blank continuous casting crystallizer covering slag which comprises the following components in percentage by weight: 54-57% of wollastonite, 9-13% of fluorite, 9-13% of sodium carbonate, 0-1% of lithium carbonate, 5-7% of glass dust, 8-12% of vanadine soil, 2.5-2.7% of soot carbon and 3-3.5% of graphite, and comprises the chemical components in percentage by weight: 31.9-34.9% of calcium oxide, 32.1-35.1% of silicon dioxide, 7.3-8.3% of aluminium oxide, 0.5-1.5% of magnesium oxide, 0.5-1.4% of iron sesquioxide, 4.4-6.4% of fluorion, 6.5-7.5% of sodium oxide, 0-0.39% of lithium oxide, 4.5-6.0% of fixed carbon and 4-7% of gas volatile matters. The alkalinity of the covering slag, namely the ratio of CaO to SiO2, is 0.91 to 1.00, the melting point of the covering slag is 1100 DEG C to 1160 DEG C, and the viscosity of the covering slag is 0.3 to 0.6 Pa.s at 1300 DEG C. The invention can solve the problems of easy crusting, slag entrainment, slag inclusion, slag sticking on casting blank surfaces, bubbles under skins, cracks, deep chatter mark, felting, bleed-out, and the like of the covering slag in the crystallizer during high-manganese high-nitrogen low-nickel stainless steel plate blank continuous casting, and has the advantages of uniform and stable slagging in the crystallizer, good casting blank quality, difficult felting and bleed-out, and the like.

Description

technical field [0001] The invention belongs to the technical field of steelmaking auxiliary materials, and in particular relates to a mold mold powder for continuous casting of high manganese, high nitrogen and low nickel stainless steel slabs and a preparation method thereof. technical background [0002] High manganese, high nitrogen and low nickel stainless steel, represented by AlSl201, AlSl202, Jindal J1, Jindal J3, Jindal J4 and other steel grades, its main features are: [0003] 1) The shrinkage of the primary solidified billet shell of this type of steel is small. Due to the high content of alloying elements such as manganese and chromium in this type of steel, the primary solidified billet shell of the cast slab is relatively hard, and the gap between the billet shell and the mold wall is small, and the mold slag liquid slag is not easy to flow in, which is easy to cause mold slag slag Small consumption causes defects such as bonding breakout accidents, uneven dis...

AI Technical Summary

Problems solved by technology

Due to the high content of alloying elements such as manganese and chromium in this type of steel, the primary solidified billet shell of the cast slab is relatively hard, and the gap between the billet shell and the mold wall is small, and the mold slag liquid slag is not easy to flow in, which is easy to cause mold slag slag Small consumption causes bonding breakout accidents, uneven distribution of slag film, uneven heat transfer and other defects such as cracks

[0004] 2) High gas content in molten steel

Since this type of steel is a low-cost stainless steel that uses manganese and nitrogen instead of nickel, the gas in the steel, especially the nitrogen content, is relatively high. If the mold slag is not designed properly, it is easy to cause subcutaneous bubble defects in the billet.

[0005] 3) The fluidity of molten steel is poor and the castability is poor

Due to the high alloy and gas content of this type of molten steel, measures such as blowing argon at the nozzle are not suitable for casting. Therefore, the fluidity of the molten steel is poor and it is easy to stick, resulting in a low temperature at the interface between the molten steel and the mold slag, and the mold slag is not easy to Melting, prone to problems such as agglomeration of mold slag in the mold, thin liquid slag layer, slag curling, bonding breakout, etc.

[0006] To sum up, due to the characteristics of high manganese, high nitrogen and low nickel stainless steel itself, problems such as crusting, slag entrainment, slag inclusion, sticky slag on the surface of the slab, subcutaneous air bubbles, cracks, and bonded breakouts are prone to occur during the casting process.

[0007] Before the present invention, the high-manganese, high-nitrogen, low-nickel slab stainless steel mold slag products on the domestic market were basically monopolized by foreign mold slag manufacturers, including domestic mold slags with patent numbers 200810039376.8, 200410064582.6, and 200710193114.2 for stainless steel. The solution to slab continuous casting can basically be summarized as high alkalinity, low melting point, and low viscosity slag, that is, in general, the basicity of this type of mold flux is designed to be above 1.0, and the melting point is designed to be below 1100°C. The viscosity is below 0.3Pa.S, the purpose is to solve the defects of this type of steel such as cracks, poor castability, and easy bonding.

Although this kind of mold slag has a more obvious effect on solving defects such as cracks and bonding breakouts, but due to the low melting point and viscosity of the mold slag, the slag consumption is relatively high, and the slag is easy to stick and slag, resulting in the vibration of the billet. In addition, this type of mold slag has a fast melting rate and poor thermal insulation, and is prone to problems such as crusting, subcutaneous air bubbles in the slab, and increased tendency of bonding breakouts.

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