Mold flux and continuous casting process for peritectic high-alumina high-manganese cold-rolled duplex steel

Abstract

This invention discloses a mold flux and continuous casting process for peritectic high-alumina high-manganese cold-rolled duplex steel. The requirements for the mold flux are as follows: basicity = 1.20 ± 0.05, melting temperature = 1150 ± 30℃; viscosity η 1300℃ =2.5±0.5 poise; crystallization temperature=1200±20℃, crystallization rate=30%±10%. This protective slag uses a relatively high crystallization temperature, high viscosity, moderate basicity, and moderate melting temperature, which can fully meet the lubrication and heat transfer requirements of peritectic steel continuous casting process. It can effectively prevent the generation of longitudinal cracks on the billet surface, and at the same time reduce the depth of oscillation marks. Reducing the depth of oscillation marks is beneficial to suppressing the formation of transverse surface cracks and meniscus solidification hooks, thereby improving the surface quality of the billet. It can ensure that the billet is lubricated by liquid slag throughout the crystallizer process, reduce the friction of the billet in the lower part of the crystallizer, avoid the generation of transverse surface concave cracks, and reduce and avoid adhesion and steel leakage.

Description

Technical Field

[0001] This invention relates to the field of continuous casting and hot rolling, and in particular to a mold flux and continuous casting process for peritectic high-alumina and high-manganese cold-rolled dual-phase steel. Background Technology

[0002] With the development of the national economy and the upgrading of industrial structure, high-aluminum steel and high-grade bridge steel, high-strength steel, energy steel, pipeline steel and other micro-alloy steels and other high-end steel materials are widely used in key fields such as automobiles, energy and power, marine engineering and shipbuilding. However, production quality problems such as longitudinal cracks, transverse concave cracks and continuous casting leakage on the surface of slabs produced by efficient continuous casting are becoming increasingly prominent, which not only affect production efficiency, but also cause waste of resources and energy.

[0003] For steel grades such as DP and TRIP used in automobiles, strong oxidizing elements such as Al (Ti, Mn) in the steel will react with reducing substances such as SiO2 in the protective slag during the casting process, causing a sudden change in the composition of the protective slag. The basicity, melting point and viscosity of the protective slag will increase sharply. This will seriously deteriorate the performance of the protective slag in the crystallizer, resulting in insufficient lubrication and steel leakage. The slag-steel reaction will also disrupt the stability of the slag-steel interface, reduce the interfacial tension between slag and steel, and cause slag to be rolled into the molten steel, forming inclusion defects or slag leakage.

[0004] In addition, this type of steel contains high levels of Mn and microalloying elements such as Nb, V, Ti, B, Cr, and Mo. It has large solidification shrinkage, high secondary phase precipitation temperature, and thin billet shell. If the liquid slag flow is insufficient or uneven during the casting process, serious quality defects such as transverse depressions and transverse cracks on the surface of the billet and adhesion accidents will occur.

[0005] Meanwhile, the carbon content of most of these steel grades is in the subperitectic range of 0.06% to 0.18%. During the casting and solidification process, peritectic reaction and peritectic transformation inevitably occur: L + δ → γ, that is, the liquid phase L and the ferrite δ phase transform into the austenite γ phase. This phase transformation with different crystal structures generates large shrinkage stress. If the thickness of the initial billet shell formed by the molten steel in the mold is uneven during the continuous casting process, the stress is easily concentrated at the weakest point, causing surface longitudinal crack defects in the billet shell.

[0006] Therefore, the traditional high-basicity, low-viscosity peritectic steel mold flux used for this type of steel can no longer simultaneously meet the process requirements of controlling longitudinal cracks (heat transfer performance), transverse depression cracks (lubrication performance), and low reactivity (reaction of easily oxidized elements in molten steel with the mold flux) on the billet surface. Furthermore, the requirements for controlling the low reactivity of the mold flux and the low-basicity, high-viscosity performance for controlling transverse depression crack defects are contradictory to the requirements for controlling the high-basicity, low-viscosity performance for controlling longitudinal crack defects caused by peritectic reaction in the billet, and cannot be coordinated. Therefore, the research on mold flux technology and continuous casting process for this type of steel has become a technical challenge and research hotspot in the metallurgical industry. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a mold protective slag for peritectic high-aluminum high-manganese cold-rolled dual-phase steel that meets the lubrication and heat transfer requirements of the peritectic steel continuous casting process; the present invention also provides a continuous casting process for peritectic high-aluminum high-manganese cold-rolled dual-phase steel that effectively improves the quality of the cast billet.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: the requirements for the crystallizer protective slag are as follows: basicity = 1.20 ± 0.05, melting temperature = 1150 ± 30℃; viscosity η 1300℃ =2.5±0.5 poise; crystallization temperature=1200±20℃, crystallization rate=30%±10%.

[0009] Furthermore, the requirements for the mold flux in the crystallizer are: η 1300℃ ×V c =1.8~3.5、η 1300℃ / t=1.5~2.5; where V c t is the continuous casting speed, in m / min; t is the melting rate of the protective slag, in s.

[0010] Furthermore, the mold flux contains 3 wt% to 5 wt% graphite and 1 wt% or less carbon black.

[0011] To solve the above-mentioned technical problems, the process of the present invention adopts the above-mentioned mold protective slag. The technical solution adopted is: during the continuous casting process, the thickness of the liquid slag layer of the mold protective slag is controlled at 8-15mm, the thickness of the powder slag layer is controlled at 20-30mm, and the total thickness of the three-layer structure of the protective slag is controlled at 35-45mm.

[0012] Furthermore, during the continuous casting process, the crystallizer employs a weak cooling process, with a narrow face taper of 1.15% ± 0.05%; the minimum operating speed of the continuous casting machine is 0.9 m / min, and the heat flow difference between the crystallizer's symmetrical planes is ≤ 0.20 mW / m. 2 Heat flux difference ≤ 0.10mW / m 2 .

[0013] Furthermore, during the continuous casting process, the billet is kept at 800℃ or below and cooled slowly, with the cooling rate controlled at ≤10℃ / h; the billet's hot charging temperature into the heating furnace is >800℃ or <400℃.

[0014] The beneficial effects of adopting the above technical solution are as follows: The protective slag of this invention uses a higher crystallization temperature, higher viscosity, moderate basicity, and moderate melting temperature, which can fully meet the lubrication and heat transfer requirements of peritectic steel continuous casting process. It can effectively prevent the generation of longitudinal cracks on the surface of the billet, and at the same time, it can reduce the depth of oscillation marks. Reducing the depth of oscillation marks is beneficial to suppressing the formation of transverse surface cracks and meniscus solidification hooks, thereby improving the surface quality of the billet. The protective slag of this invention can ensure that the billet is lubricated by liquid slag throughout the crystallizer process, reduce the friction of the billet in the lower part of the crystallizer, avoid the generation of transverse surface depression cracks, and avoid the high-risk area of ​​crystallization temperature greater than or equal to 1220°C caused by simply increasing basicity in the past, thereby reducing and avoiding adhesion and steel leakage.

[0015] The continuous casting process of this invention is formulated based on the solidification and phase transformation characteristics of this type of steel. It promotes uniform growth of the initial billet shell and reduces phase transformation stress and thermal stress. It has achieved unexpected good results, improved product quality, and enhanced the company's economic benefits and quality brand effect. Attached Figure Description

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] Figure 1 This is a graph showing the solidification characteristics of the W780QX steel described in this invention, specifically the density variation with temperature.

[0018] Figure 2 This is a phase transformation characteristic diagram of the W780QX steel described in this invention, showing the precipitation phase change with temperature. Detailed Implementation

[0019] The mold flux and continuous casting process for this peritectic high-aluminum high-manganese cold-rolled duplex steel are particularly suitable for producing peritectic high-aluminum high-manganese microalloyed steel, represented by W780QX. The composition and mass percentage of W780QX steel are shown in Table 1 below:

[0020] Table 1: Composition of W780QX Steel Grade

[0021]

[0022] In Table 1, the balance of the components is Fe and unavoidable impurities.

[0023] During continuous casting, the peritectic high-alumina and high-manganese cold-rolled dual-phase steel must ensure suitable crystallization performance and low reactivity under the high viscosity of the mold flux. Under the premise of low reactivity of the mold flux, it is necessary to effectively coordinate the lubrication and heat transfer functions of the mold flux, and control the surface longitudinal crack defects while avoiding the generation of deep vibration marks and transverse depression defects on the billet surface and the occurrence of adhesion accidents.

[0024] In continuous casting, to reduce the reaction between strong oxidizing elements such as Al in the steel and reducing substances such as SiO2 in the protective slag, a mold flux with low SiO2 content and low basicity is generally required to control excessive increase in basicity. To reduce the depth of oscillation marks on the billet and thus suppress transverse concave crack defects on the billet surface, the viscosity of the mold flux needs to be increased to facilitate the formation of solidification hooks on the meniscus of the mold. Therefore, the inventors believe that excessively high basicity, excessively low viscosity, and excessive slag consumption of the protective slag are the main causes of transverse concave crack defects in billets of this type of steel.

[0025] Based on the above reasons, the mold flux for this peritectic high-alumina high-manganese cold-rolled dual-phase steel needs to simultaneously address the process requirements of controlling longitudinal cracks (heat transfer performance), transverse concave cracks (lubrication performance), and low reactivity (reaction between easily oxidized elements in molten steel and the mold flux) on the billet surface. This requires employing methods such as reducing basicity and increasing viscosity to improve the uniform flow of the molten slag and enhance lubrication performance, while maintaining the original strong crystallinity and high crystallization temperature. This increases the thermal resistance of the slag film, maintains its adiabatic and slow cooling properties, and prevents excessive heat dissipation from the molten steel, thereby achieving the goal of slow and uniform solidification of the billet shell. The mold flux's high crystallization temperature, high viscosity, and moderate basicity and melting temperature can fully meet the lubrication and heat transfer requirements of the peritectic steel continuous casting process.

[0026] The requirements for the protective slag in the crystallizer are as follows:

[0027] 1) Basicity, i.e., CaO / SiO2: Basicity is an important indicator reflecting the ability of the protective slag to absorb inclusions in molten steel and the quality of its lubrication performance. Generally, higher basicity means a greater ability to absorb inclusions, but it also increases the crystallization temperature, leading to deterioration in heat transfer and lubrication performance. Taking all factors into consideration, the basicity requirement for the protective slag in this crystallizer is CaO / SiO2 = 1.20 ± 0.05.

[0028] 2) Melting Temperature: Increasing the solidification temperature of the protective slag can increase the thickness of the solid protective slag film and reduce heat transfer between the billet shell and the mold. However, excessively high solidification temperatures will disrupt the liquid lubrication effect between the billet shell and the mold, increasing the possibility of adhesive pull-out; excessively low solidification temperatures will increase heat flow within the mold and the transverse thermal gradient, causing longitudinal cracks in the billet. The liquidus temperature of high-manganese, high-alumina steel is about 80°C lower than that of ordinary steel grades; therefore, the protective slag needs a low melting point to ensure the thickness of the liquid slag layer. Taking all factors into consideration, the melting point range of the protective slag for this mold is 1150±30°C.

[0029] 3) Viscosity: Increasing viscosity not only adapts to low casting speed conditions but also helps achieve uniform slag flow, reducing oscillation depth and lateral indentation. Furthermore, increased viscosity is beneficial for reducing heat transfer. Considering the relationship between viscosity and casting machine speed (η×V=1.5-3.0) and the melting rate of the protective slag (η / t=1.5-2.5), and taking into account both lubrication characteristics and heat transfer requirements, to address the issue of excessively high slag consumption in existing systems, the viscosity range of the protective slag in this crystallizer at 1300℃ is set at 2.5±0.5 poise, and η... 1300℃ ×V c =1.5-3.5、η 1300℃ / t=1.5-2.5, where η 1300℃ V represents the viscosity of the protective slag in this crystallizer at 1300°C. c t is the continuous casting speed, in m / min; t is the melting rate of the protective slag, in s.

[0030] 4) Crystallization Characteristics: Increasing the crystallization temperature aims to increase the thickness of the solid slag film and improve crystal roughness, which helps reduce the conduction and heat transfer of the slag film and increases thermal resistance. This is fundamental to solving crack defects in peritectic steel. However, excessively high temperatures can lead to poor lubrication and inclusions. Crystallization characteristics include two aspects: crystallization rate and crystallization layer structure (i.e., mineral phase characteristics and thermal conductivity). First, appropriately changing the mineral phase composition to increase coarse grains further delays heat transfer and improves the thermal conductivity of the slag film. Second, determining a reasonable crystallization rate. Decreasing basicity and increasing viscosity affect the crystallization temperature of the protective slag. To suppress this phenomenon, it is necessary to find ways to increase the crystallization rate from other components, which is key to developing protective slags for peritectic steel. The protective slag for this crystallizer, by adding 2wt% to 4wt% of alkaline earth metal oxides MnO2, BaO, and B2O3 to the slag, can slow down the change of the viscosity-temperature curve, thus preventing severe degradation after adsorbing high-melting-point substances; it can effectively solve the lubrication and heat transfer of the cast billet, prevent cracks, and improve the quality of the cast billet.

[0031] The flux Al2O3 is the form of the network structure in the protective slag melt. Its presence increases the viscosity of the protective slag and reduces the amount of crystal precipitation. Therefore, it is the main factor in adjusting these two properties of the slag. Below 4wt%, the amount of crystal precipitation cannot be controlled, and above 12%, the effect on viscosity is too great. Therefore, the ideal range for Al2O3 is 4wt% to 12wt%.

[0032] Flux (F) and Na₂O are the most effective fluxes for reducing the viscosity of protective slag and are also essential components for the formation of gunmetal. Gunmetal (3CaO•2SiO₂•CaF₂) has a melting point of around 1410℃ and effectively balances the functions of heat transfer and lubrication in the slag, making it the most important crystal in the protective slag. When the basicity of the protective slag is constant, the crystallization temperature is highest when the mass fraction of F is 6%–8% and the mass fraction of Na₂O is 4%–6%, while the effect on viscosity is minimal. At this point, the crystallization temperature range is 1200±20℃, and the crystallization rate range is 30%±10%.

[0033] In the above section on crystallization characteristics, the content ranges of MnO2, BaO, B2O3, Al2O3, F, and Na2O are designed to address the issue that decreased basicity and increased viscosity affect the crystallization temperature of the protective slag (lowering the crystallization temperature). To suppress this phenomenon, it is necessary to find ways to improve the crystallization rate from other components.

[0034] 5) Reasonable carbon composition: To ensure good fluidity and control a suitable slag layer structure, a reasonable carbon composition is adopted. If the carbon composition of the protective slag is unreasonable, it will cause excessive sintering, forming thick and hard slag strips that are difficult to melt and embed into the surface of the billet, resulting in surface depressions. The protective slag is added in the form of carbon black, graphite, and coke powder. Carbon black has the lowest combustion temperature, while graphite has the highest. Carbon black in the protective slag can reduce its melting rate, but its use can easily cause transverse depressions and cracks on the billet. The protective slag of this crystallizer contains 3wt%–5wt% graphite and 1wt% or less carbon black, which has a significant effect on eliminating depressions and cracks. This ensures that the slag layer thickness is not less than 8mm during casting, the slag consumption is appropriate and stable at the same casting speed, the slag ring is small, and the slag surface is active.

[0035] 6) In summary, the basicity of the protective slag in this crystallizer is 1.20 ± 0.05, the melting temperature is 1150 ± 30℃, and the viscosity η is... 1300℃ =2.5±0.5 poise, and η 1300℃ ×V c =1.8~3.5、η 1300℃ / t=1.5~2.5; where V c t is the continuous casting speed in m / min, and t is the melting rate of the protective slag in seconds; crystallization temperature = 1200±20℃, crystallization rate = 30%±10%; the main raw materials of the protective slag in this crystallizer have the following mass percentages: MnO2 2%~4%, BaO 2%~4%, B2O3 2%~4%, Al2O3 4%~12%, F 6%~8%, Na2O 4%~6%, graphite 3%~5%, carbon black ≤1%, and CaO and / or SiO2. The amount of CaO and SiO2 is determined according to the basicity.

[0036] The continuous casting process for this peritectic high-aluminum high-manganese cold-rolled duplex steel uses the aforementioned mold flux, and the process requirements are as follows:

[0037] 1) The requirements for the use and operation of protective slag are as follows:

[0038] ① The thickness of the liquid slag layer of the crystallizer protective slag is 8-15mm, the thickness of the powder slag layer is 20-30mm, and the thickness of the three-layer structure of the protective slag is controlled between 35-45mm;

[0039] ② When starting the casting process, a small amount of protective slag can be added, but the black surface operation should not be maintained to prevent slag entrapment; when the liquid level in the crystallizer is 50mm higher than the immersion nozzle and steel outlet, protective slag should be added according to the normal operating procedure.

[0040] ③ When adding protective slag, the principles of adding small amounts frequently and evenly should be followed;

[0041] ④ Ensure the crystallizer operates with black slag and no red slag is allowed. If slag streaks appear, they should be handled according to their size. Large slag streaks should be removed, and the entire crystallizer circumference should be cleaned. Small slag streaks should be broken or bent with an oxygen-burning tube.

[0042] ⑤ When the liquid level in the crystallizer is stable, it is forbidden to continuously stir the crystallizer along the wall with a slag skimmer.

[0043] ⑥ The slag strips inside the heat exchanger tundish and crystallizer must be thoroughly removed to prevent slag entrapment caused by liquid level fluctuations;

[0044] ⑦ When the molten steel in the crystallizer is agitated, the nozzle should be replaced in time to prevent the nozzle diameter from increasing in the later stages of use, which would cause large agitation of the liquid surface in the crystallizer and result in poor lubrication of the protective slag.

[0045] ⑧ If the slag has crusts and hard lumps, use a slag-removing stick to press down along the edge. If there are any abnormal phenomena such as clumping, replace the slag with new slag in time.

[0046] ⑨ Add enough protective slag to the areas where red light is visible and flames are appearing.

[0047] 2) Based on the solidification and phase transformation characteristics of peritectic high-aluminum high-manganese cold-rolled dual-phase steel, formulate a continuous casting process that matches the solidification and phase transformation characteristics of the steel:

[0048] 2.1) This type of steel exhibits a significant density change during solidification in the crystallizer, indicating substantial solidification shrinkage of the billet shell. (See...) Figure 1 Therefore, due to the use of a weak cooling process, the taper of the narrow face of the crystallizer is within the range of 1.15% ± 0.05%; the minimum operating speed of the continuous casting machine is 0.9 m / min, that is, the operating speed of the casting machine is ≥ 0.9 m / min; the heat flow difference on the symmetry plane of the crystallizer is ≤ 0.20 mW / m. 2 Heat flux difference ≤ 0.10mW / m 2 The crystallizer's symmetry planes include inner and outer arcs and symmetrical surfaces on the left and right sides.

[0049] 2.2) This type of steel begins to precipitate α-ferrite at 800℃ and below, and bainite and martensite begin to precipitate below 600℃. Precipitation is basically completed below 400℃. (See...) Figure 2 Therefore, for this type of steel billet, the temperature is held at 800℃ or below and cooled slowly, and the temperature drop rate of the billet, i.e. the cooling rate, is controlled at ≤10℃ / h; the hot charging temperature of the billet into the heating furnace is >800℃ or <400℃, in order to avoid phase transformation cracks or thermal stress cracks in the multiphase region during the heating process of the billet.

[0050] 3) After adopting the above-mentioned mold mold flux and continuous casting process, the resulting billet has no quality defects such as surface longitudinal cracks and surface transverse concave cracks. There is no adhesion phenomenon during the casting process, and the incidence of linear defects on the surface of hot-rolled coils has decreased from 20% to less than 0.1%.

[0051] Example 1: The mold flux and continuous casting process for this peritectic high-alumina high-manganese cold-rolled duplex steel are described in detail below:

[0052] 1) The continuous casting production of W780QX peritectic high-alumina high-manganese microalloyed steel uses the following raw materials for the mold flux: MnO2 3%, BaO 2%, B2O3 2%, Al2O3 12%, F 7%, Na2O 6%, graphite 4%, carbon black 1%, CaO 34.4%, SiO2 28.6%, basicity = 1.15, melting temperature 1120℃; viscosity η 1300℃ =3.0 berths, and η 1300℃ ×V c =3.5、η 1300℃ / t=1.5, crystallization temperature=1180℃, crystallization rate=20%.

[0053] 2) Process parameters: A weak cooling process is adopted; the taper of the narrow face of the crystallizer is 1.10%; the casting machine speed is 1.15 m / min; and the heat flow difference between the symmetrical planes of the crystallizer is 0.20 mW / m. 2 Heat flux difference 0.10mW / m 2 The thickness of the liquid slag layer in the crystallizer is controlled at 8-10 mm, the thickness of the powder slag layer is controlled at 20-22 mm, and the thickness of the three-layer structure of the protective slag is controlled at 35-38 mm. The billet is kept at a temperature below 800℃ and cooled slowly, with the cooling rate controlled at 10℃ / h. The hot charging temperature of the billet into the heating furnace is 805℃.

[0054] 3) The billet obtained in this embodiment has no quality defects such as longitudinal cracks or transverse depression cracks on the surface. There is no adhesion phenomenon during the casting process, and no linear defects on the surface of the hot-rolled coil appear.

[0055] Example 2: The mold flux and continuous casting process for this peritectic high-alumina high-manganese cold-rolled duplex steel are described in detail below:

[0056] 1) The continuous casting production of W780QX peritectic high-alumina high-manganese microalloyed steel uses the following raw materials for the mold flux: MnO2 2%, BaO 3%, B2O3 4%, Al2O3 8%, F 6%, Na2O 7%, graphite 3%, carbon black 0.9%, CaO 36.7%, SiO2 29.4%, basicity = 1.25, melting temperature 1180℃; viscosity η 1300℃ =2.0 berths, and η 1300℃ ×V c =1.8、η 1300℃ / t=2.5, crystallization temperature=1220℃, crystallization rate=40%.

[0057] 2) Process parameters: A weak cooling process is adopted; the taper of the narrow face of the crystallizer is 1.20%; the casting machine speed is 0.9 m / min; and the heat flow difference between the symmetrical planes of the crystallizer is 0.14 mW / m. 2 Heat flux difference 0.05mW / m 2 The thickness of the liquid slag layer in the crystallizer is controlled at 10-12 mm, the thickness of the powder slag layer is controlled at 24-26 mm, and the thickness of the three-layer structure of the protective slag is controlled at 38-40 mm. The billet is kept at a temperature below 800℃ and cooled slowly, with the cooling rate controlled at 8℃ / h. The hot charging temperature of the billet into the heating furnace is 397℃.

[0058] 3) The billet obtained in this embodiment has no quality defects such as longitudinal cracks or transverse depression cracks on the surface. There is no adhesion phenomenon during the casting process, and no linear defects on the surface of the hot-rolled coil appear.

[0059] Example 3: The mold flux and continuous casting process for this peritectic high-alumina high-manganese cold-rolled duplex steel are described in detail below:

[0060] 1) The continuous casting production of W780QX peritectic high-alumina high-manganese microalloyed steel uses the following raw materials for the mold flux: MnO2 4%, BaO 4%, B2O3 3%, Al2O3 4%, F 8%, Na2O 8%, graphite 5%, carbon black 0.5%, CaO 34.4%, SiO2 28.6%, basicity = 1.20, melting temperature 1150℃; viscosity η 1300℃ =2.5 poise, and η 1300℃ ×V c =2.5、η 1300℃ / t=2.0, crystallization temperature=1200℃, crystallization rate=30%.

[0061] 2) Process parameters: A weak cooling process is adopted; the taper of the narrow face of the crystallizer is 1.15%; the casting machine speed is 1.0 m / min; and the heat flow difference between the symmetrical planes of the crystallizer is 0.16 mW / m. 2 Heat flux difference 0.07mW / m2 The thickness of the liquid slag layer in the crystallizer is controlled at 12-15 mm, the thickness of the powder slag layer is controlled at 28-30 mm, and the thickness of the three-layer structure of the protective slag is controlled at 42-45 mm. The billet is kept at a temperature below 800℃ and cooled slowly, with the cooling rate controlled at 6℃ / h. The hot charging temperature of the billet into the heating furnace is 802℃.

[0062] 3) The billet obtained in this embodiment has no quality defects such as longitudinal cracks or transverse depression cracks on the surface. There is no adhesion phenomenon during the casting process, and no linear defects on the surface of the hot-rolled coil appear.

Claims

1. A mold flux for peritectic high-alumina high-manganese cold-rolled duplex steel, characterized in that, The requirements for the mold flux are as follows: basicity = 1.20 ± 0.05, melting temperature = 1150 ± 30℃; viscosity η 1300℃ =2.5±0.5 poise; crystallization temperature=1200±20℃, crystallization rate=30%±10%; η 1300℃ ×V c =1.8~3.5、η 1300℃ / t=1.5~2.5; where V c t is the continuous casting speed, in m / min; t is the melting rate of the protective slag, in s. The protective slag of the crystallizer contains 3wt% to 5wt% graphite and 1wt% or less carbon black.

2. A continuous casting process for peritectic high-alumina high-manganese cold-rolled duplex steel, employing the mold flux as described in claim 1, characterized in that: During continuous casting, the thickness of the liquid slag layer and the powder slag layer of the mold protective slag are controlled at 8-15 mm and 20-30 mm respectively, and the total thickness of the three-layer structure of the protective slag is controlled at 35-45 mm.

3. The continuous casting process for peritectic high-alumina high-manganese cold-rolled duplex steel according to claim 2, characterized in that: During the continuous casting process, the crystallizer employs a weak cooling process, with a narrow face taper of 1.15% ± 0.05%; the minimum operating speed of the continuous casting machine is 0.9 m / min, and the heat flow difference between the crystallizer's symmetrical planes is ≤ 0.20 mW / m. 2 Heat flux difference ≤ 0.10mW / m 2 .

4. The continuous casting process for peritectic high-alumina high-manganese cold-rolled duplex steel according to claim 2 or 3, characterized in that: During the continuous casting process, the billet is kept at 800℃ or below and cooled slowly, with the cooling rate controlled at ≤10℃ / h; the billet is charged into the heating furnace at a temperature >800℃ or <400℃.

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