A method for smelting and deoxidizing a slab Q195 steel

Abstract

The application discloses a smelting and deoxidizing method of slab Q195 steel, which comprises the following steps: step 1), adding molten iron and scrap steel into a converter, and smelting by adopting N2-Ar combined blowing mode; step 2), adding composite deoxidizing materials according to a proportion during tapping, and completing deoxidizing and alloying by means of steel flow impact, impact mixing and Ar blowing stirring refining; and step 3), casting the molten steel obtained in the step 2) by means of slab continuous casting. While enhancing deoxidizing, measures are taken to ensure that most of high-melting-point deoxidizing products Al2O3 and deoxidizing products of Ca, Si and Mn form low-melting-point composite phases, the low-melting-point composite phases are in liquid state at a steelmaking temperature, are easily removed from the molten steel by means of Ar blowing stirring refining, the cleanliness of the molten steel is improved, and the steel fluidity and normal production of slab continuous casting are ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steelmaking, in particular to a slab Q195 steel smelting deoxidation method. BACKGROUND

[0002] The plate strip product is all processing material, and the strip steel is processed into different products on different user processing lines to become the final product and be applied to various industries. The downstream users of the hot-rolled strip steel Q195 with large amount mainly include pickling cold rolling, galvanizing, cold forming, cold stamping, pipe bending, pipe rolling, pipe cutting and welding, and the like. The strip steel product is subjected to size inspection again during the user processing, and if the product has defects, the defects will be shown during the processing to cause objection. The production control of the strip steel product is higher than that of general building material products, and the strip steel product is mainly based on quality in the market, while the production of general building material is biased towards economy. The slab Q195 is prone to have substandard deoxidation depth, and the cold bending and cold working performance is unstable, which affects the product quality of the user and causes loss.

[0003] The slab Q195 is very critical in smelting deoxidation, and is a key link for determining the product quality. While enhancing deoxidation, measures are taken to ensure that most of the deoxidation product Al2O3 is removed from the molten steel, to ensure the flowability of the molten steel and to ensure the normal production of the slab continuous casting. The original deoxidation process of the company only uses Al block deoxidation. A large amount of high-melting-point flocculent deoxidation Al2O3 product is generated by single Al block deoxidation, which cannot be effectively removed from the molten steel in the current process. The water gap is frequently blocked during casting, which causes the oxygen content of the molten steel to be unable to meet the requirements. It is observed that the relative density of the Al block is relatively low, only 2.7 g / cm 3 , the deoxidation Al block added during the converter tapping floats on the surface of the high-temperature molten steel. Even if it is melted into Al liquid, it also floats on the surface. The deoxidation can only be realized by the impact and mixing of the tapping molten steel flow to make the Al liquid contact with the high-temperature and high-oxidizing molten steel. However, it is quite difficult to realize the contact of all the molten steel with the Al liquid and complete the deoxidation in a short tapping time. There is incomplete or uneven deoxidation of part of the molten steel during the tapping. Although the ladle bottom Ar stirring is used to stir the molten steel, a small amount of high-oxidizing final slag is discharged at the late stage of the tapping, which causes the Al liquid floating on the surface of the molten steel to be rapidly oxidized and lose the deoxidation ability to become Al2O3 and enter the slag. The Al2O3 generated by the part of Al completing the deoxidation task is in the form of dispersed fine solid flocculent oxide with a high melting point of 2050℃, which is difficult to be removed from the molten steel. The high-melting-point Al2O3 is precipitated and adhered to the water gap during the casting of the molten steel, which causes the water gap to be blocked, the slab process is extremely unstable, and the single Al deoxidation process is not suitable for the current process of the company. SUMMARY

[0004] The present application aims to provide a slab Q195 steel smelting deoxidation method, solve the slab continuous casting single Al amount deoxidation multiple poor fluidity of molten steel, water gap casting difficult and unable to cast and appear multiple water gap dead forced stop pouring accident.

[0005] To solve the above technical problems, the present application adopts the following technical solutions:

[0006] A slab Q195 steel smelting deoxidation method, comprising the following steps:

[0007] Step 1) converter adding molten iron and scrap steel, using nitrogen argon (N2→Ar) combined blowing mode smelting;

[0008] Step 2) tapping according to the proportion of adding composite deoxidizing material, relying on the impact of steel flow, mixing and blowing Ar stirring refining, completing deoxidation alloying;

[0009] Among them, the composite deoxidizing material includes: deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, FeSi alloy; The adding amount of each substance is as follows: deoxidizer 3.5-5.5 kg / t, BaCaAlSi 0.55-1.0 kg / t, aluminum block 0.36-0.87 kg / t, MnSi alloy 0.6-2.5 kg / t, FeSi 0.36-0.88 kg / t,

[0010] Step 3) the molten steel obtained in step 2) is subjected to slab continuous casting.

[0011] Further: in the step 1), smelting includes the following steps:

[0012] Step 1.1) the converter is loaded in stages according to the furnace service period and the hearth;

[0013] Step 1.2) the converter is loaded with molten iron and scrap steel; According to the weight percentage, it is 80-85% of molten iron and 15-20% of scrap steel;

[0014] Step 1.3) slab Q195 steel is smelted by nitrogen argon combined blowing mode in the smelting process, and the composition of slab Q195 steel at the end of smelting is controlled to be C≤0.06%, P≤0.025%, S≤0.030%.

[0015] Further: the C content in the molten iron is ≥3.60%, the Si content is 0.08-0.65%, the P content is ≤0.150%, the S content is ≤0.040%, and the As content is ≤0.060%.

[0016] Further: the temperature of the molten iron is 1200-1350℃.

[0017] Further: the tapping temperature is 1615-1665℃.

[0018] Further, in the step 2), the deoxidizing alloying comprises the following steps:

[0019] Step 2.1) Controlling to reach the slab Q195 steel smelting endpoint requirement to perform the deoxidizing alloying of tapping;

[0020] Step 2.2) When the molten steel is tapped to 1 / 3 of the ladle, the composite deoxidizing material is added to perform the deoxidizing alloying, and meanwhile, the Ar blowing stirring is performed on the molten steel, the deoxidation products are removed, and the molten steel is refined;

[0021] Step 2.3) The slag stopping is positioned by the slag stopping trolley, and the amount of the slag stopping is controlled to be less than or equal to 80 mm;

[0022] Step 2.4) After the deoxidizing alloying of tapping is completed, the Ar blowing stirring is performed on the ladle for refining, the composition of the molten steel is adjusted, the oxygen activity is adjusted, the temperature of the molten steel is adjusted, and meanwhile, the optimized Ar blowing refining stirring process is performed in the process of the Ar blowing refining stirring, so that the high-melting-point Al2O3 deoxidation products collide with the deoxidation oxides of calcium, silicon and manganese to gather and grow, a low-melting-point composite phase (liquid state) is formed, and is removed from the molten steel into the top slag of the ladle under the optimized Ar blowing stirring driving condition, so that the cleanliness of the molten steel is improved, and the problem of the high-melting-point Al2O3 phase sticking to the nozzle wall caused by the precipitation of the high-melting-point Al2O3 phase in the process of casting is reduced; the blowing intensity of the Ar and the stirring time are controlled;

[0023] Step 2.5) When the composition, the oxygen activity, the temperature and the time of the Ar blowing refining stirring meet the process control requirements, the slab continuous casting can be started.

[0024] Further, in the step 3), the slab continuous casting pouring comprises the following steps:

[0025] The slab continuous casting is poured according to the full protection pouring requirement, and the full protection pouring comprises the long nozzle protection pouring of the ladle, the submerged nozzle pouring of the tundish and the protection slag protection pouring of the crystallizer, so that the molten steel is prevented from being aerated and secondarily oxidized;

[0026] The ladle pouring requires the long nozzle protection pouring, the long nozzle is inserted into the liquid surface of the tundish by 180-250 mm, the tundish is operated in full liquid surface, the tundish pouring adopts the sectional submerged nozzle, the submerged nozzle is inserted into the crystallizer by 110-135 mm, and the crystallizer liquid surface is protected by the special crystallizer protection slag;

[0027] The slab continuous casting pouring is performed according to the three-stable control strict rules of “stabilizing the tundish temperature, stabilizing the control casting speed and stabilizing the control crystallizer liquid surface”, so that the qualified cast slab is produced.

[0028] Compared with the prior art, the present application has at least one of the following beneficial effects:

[0029] (1) In the process of enhancing deoxidation, measures are taken to ensure that most of the high-melting-point deoxidation products Al2O3 and Ca, Si, Mn deoxidation products form low-melting-point composite phases, which are in a liquid state at steelmaking temperature and are beneficial to be removed from the molten steel, thereby improving the cleanliness of the molten steel and ensuring the fluidity of the molten steel and ensuring the normal production of slab continuous casting.

[0030] (2) The independent innovative composite deoxidation process of steelmaking greatly reduces the production cost of strip steel.

[0031] (3) Composite deoxidation mainly uses Ca, Al, Si, and Mn four deoxidation elements to deoxidize, and the deoxidation products formed are CaO, Al2O3, SiO2, and MnO. Under the impact, mixing and Ar blowing stirring of the steel flow, the four deoxidation products are easily collided and gathered to form low-melting-point composite phases. The low-melting-point deoxidation products are in a liquid state at the steelmaking temperature, and the liquid inclusions are easily removed from the steel by Ar blowing stirring refining, thereby reducing the residual deoxidation inclusions in the steel under the condition of ensuring the deoxidation depth, improving the cleanliness of the steel, and ensuring the fluidity of the steel, realizing the stable control of slab continuous casting. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 The product prepared in the comparative example of the present application appears cold stamping processing cracking diagram.

[0033] Figure 2 The product prepared in the comparative example of the present application appears strip steel edge cracking diagram.

[0034] Figure 3 The product prepared in the comparative example of the present application appears porosity diagram. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0036] Example 1:

[0037] A method for smelting and deoxidizing a slab Q195 steel; comprising the following steps:

[0038] Step 1) Add molten iron and scrap steel to the converter, and smelt using N2→Ar nitrogen-argon combined blowing mode:

[0039] The converter is filled with molten iron and scrap steel in stages according to the service life and the hearth of the converter; the C content of the molten iron is ≥3.60%, the Si content is 0.08-0.65%, the P content is ≤0.150%, the S content is ≤0.040%, the As content is ≤0.060%, and the temperature of the molten iron is 1200-1350°C; the slab Q195 steel is smelted by using a nitrogen-argon combined blowing mode, the blowing amount is executed according to the set value of the automatic control software, and the N content in the steel is strictly controlled; the end-point composition of the slab Q195 steel is controlled, and the end-point of the slab Q195 steel is required to have a C content ≤0.06%, a P content ≤0.025%, and a S content ≤0.030%; and the tapping temperature is 1615-1665°C.

[0040] Step 2) the composite deoxidizing material is added according to the proportion, and the deoxidizing and alloying are completed by relying on the impact and mixing of the tapping steel flow and blowing Ar stirring refining;

[0041] The tapping deoxidizing and alloying are performed when the control reaches the end-point of the slab Q195 steel smelting;

[0042] When the molten steel is tapped to 1 / 3 of the ladle, the composite deoxidizing material is added for deoxidizing and alloying, wherein the composite deoxidizing material comprises a deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, and FeSi alloy; meanwhile, the molten steel is blown with Ar for stirring, the stirring is uniform, the deoxidizing products are removed, and the cleanliness of the molten steel is improved; the slag stopping is positioned by using a slag stopping trolley, and the amount of the slag is controlled to be ≤80mm; after the tapping deoxidizing and alloying are completed, the ladle is blown with Ar for refining and stirring, the composition of the molten steel is adjusted, the oxygen content is adjusted, the oxygen activity is adjusted, and the temperature of the molten steel is adjusted in the process of the blowing Ar refining and stirring, and meanwhile, the optimized blowing Ar refining and stirring process is executed in the process of the blowing Ar refining and stirring, so as to promote the collision, gathering and growing of the high-melting-point Al2O3 deoxidizing products and the deoxidizing oxides of calcium, silicon and manganese, form a low-melting-point composite phase (liquid state), and be removed from the molten steel into the top slag of the ladle under the optimized blowing Ar stirring driving conditions, so as to improve the cleanliness of the molten steel and reduce the problem of the high-melting-point Al2O3 phase sticking to the water gap wall in the casting process.

[0043] The optimized blowing Ar stirring process is strictly executed in the process of the blowing Ar refining and stirring at the blowing Ar refining and stirring station, and the key points of the control are that the blowing Ar gas intensity and the blowing Ar refining and stirring time must meet the requirements. When the composition, oxygen activity, temperature and time of the blowing Ar refining and stirring meet the process control requirements, the slab continuous casting can be started.

[0044] Step 3) the obtained molten steel is cast by slab continuous casting;

[0045] The slab continuous casting safety protection casting requires casting, full protection casting including ladle long nozzle, tundish immersion nozzle and mold flux protection casting, preventing the steel liquid from generating air absorption and secondary oxidation; the ladle casting requires long nozzle protection casting, the long nozzle is inserted into the tundish liquid surface by 180-250 mm, the tundish full liquid surface operation, the tundish casting adopts sectional immersion nozzle, the immersion nozzle is inserted into the mold by 110-135 mm, and the mold liquid surface adopts special mold flux protection casting. The slab continuous casting casting executes three stable control strict rules "stable tundish temperature, stable control casting speed and stable control mold liquid surface", and produces qualified casting blank.

[0046] Other embodiments are operated according to the preparation method in the embodiment 1. The application is further described in detail in combination with the following examples, as shown in Table 1.

[0047] Table 1 Process parameter table of the embodiment of the application

[0048]

[0049]

[0050] As seen from Table 1, the slab Q195 steel produced by each embodiment has low carbon in the steel liquid at the end of smelting, high end temperature, high oxygen content in the steel, relatively increased deoxidizing material and alloy, relatively high carbon in the steel liquid at the end of smelting, relatively low end temperature, relatively low oxygen content in the steel, and relatively reduced deoxidizing material and alloy; when there are more residues in the ladle during the smelting process and the tapping slag blocking occurs abnormally, the proportion of the composite deoxidizing material, the stirring time and the temperature are taken as the upper limit value, the oxygen content in the steel is well controlled by adjusting the process, the slab Q195 steel produced by the application reduces the cold stamping cracking, the strip edge breaking and the air hole in the casting blank.

[0051] The composite deoxidizing mainly uses Ca, Al, Si and Mn four deoxidizing elements to deoxidize at the same time, and the deoxidizing products formed are CaO, Al2O3, SiO2 and MnO. The four deoxidizing products are extremely easy to collide and gather to form low melting point composite phase under the impact, mixing and Ar blowing stirring of the steel flow, especially the high melting point Al2O3 is converted into low melting point deoxidizing product, which is in liquid state at the steelmaking temperature. The liquid inclusions are easily floated and removed from the steel by Ar blowing stirring, realizing the reduction of the deoxidizing inclusions remaining in the steel under the condition of ensuring the deoxidizing depth, improving the cleanliness of the steel and ensuring the fluidity of the steel, and realizing the stable control of the slab continuous casting blank quality.

[0052] The deoxidizing products formed are:

[0053]

[0054] The composite deoxidation mainly uses Ca, Al, Si and Mn to deoxidize simultaneously, and the deoxidation products formed are CaO, Al2O3, SiO2 and MnO. Under the impact of the steel flow, the mixing and the blowing Ar stirring, the four deoxidation products are extremely easy to collide and gather to form a low-melting-point composite phase, become low-melting-point deoxidation products, and present as liquid at the steelmaking temperature. The liquid inclusions are easily floated and removed from the steel by blowing Ar stirring, so that the deoxidation depth is ensured, the deoxidation inclusions remaining in the steel are reduced, the cleanliness of the steel is improved, the fluidity of the steel is ensured, and the stable control of the slab continuous casting is realized.

[0055] Comparative example

[0056] Single Al block deoxidation: the Al block deoxidation process is first melted into Al liquid or Al film to contact with the molten steel for deoxidation and float on the surface of the molten steel. In the process of tapping, due to the impact and mixing of the steel flow, part of the Al liquid is brought into the molten steel by the impact kinetic energy to contact with the molten steel to produce a deoxidation reaction:

[0057] The deoxidation process exists the following reactions:

[0058] → Al directly reacts with [O] in the molten steel to produce a deoxidation reaction:

[0059] 2[Al]+3[O]=[Al2O3] 夹杂物

[0060] → Al reacts with {O2} in the air:

[0061] 2[Al]+3 / 2O2=[Al2O3] 夹杂物

[0062] → Al reacts with (FeO) in the slag:

[0063] 2[Al]+3(FeO)=[Al2O3] 夹杂物 +3Fe

[0064] → Al reacts with SiO2 in the slag or the lining material:

[0065] 2[Al]+3 / 2(SiO2)=[Al2O3] 夹杂物 +3 / 2[Si]

[0066] The surface tension between [Al2O3] and the molten steel is very large after Al deoxidation. The initial deoxidation product [Al2O3] is in solid state and dispersed in the molten steel in the form of flocculation. A part of the fine [Al2O3] particles collide and gather to become larger deoxidation products under the impact, mixing and Ar blowing stirring of the molten steel flow. The larger deoxidation products float to the slag surface and are absorbed by the slag. However, the initial [Al2O3] particles are very small and cannot be removed by the stirring. They form larger deoxidation products only after a long time. At this time, the molten steel has been cast. The larger deoxidation products contact the surface of the stopper and nozzle and are deposited on the surface of the stopper and nozzle, causing the nozzle to be blocked by the deposition. The deposition has a great influence on the flowability of the molten steel.

[0067] The collision, gathering and growing process of [Al2O3] deoxidation inclusions in the molten steel: The removal of [Al2O3] deoxidation inclusions in the molten steel is a process of collision, gathering and growing and floating by the Ar blowing stirring and being absorbed by the top slag. Under the condition of single Al deoxidation, the deoxidation product in the molten steel is mainly solid [Al2O3] particles. The melting point of Al2O3 is as high as 2054°C and the density is 3.5 g / cm 3 The solid Al2O3 particles are difficult to be removed from the molten steel. If they are not removed in time, the larger particles remaining in the molten steel form brittle inclusions, which have a great harm to the quality of the steel.

[0068] The single Al block deoxidation has the following disadvantages:

[0069] (1) The relative density of Al block is relatively low, only 2.7 g / cm 3 The deoxidation Al block added in the converter is floated on the surface of the high temperature molten steel. Even if it is melted into Al liquid, it is also floated on the surface. The deoxidation effect can be achieved only by the impact and mixing of the molten steel flow. It is difficult for all the molten steel to contact with the Al liquid in a short time. Some of the molten steel is not completely or uniformly deoxidized. Although the bottom Ar stirring is used in the ladle, a small amount of high oxidizing final slag is discharged at the late stage of tapping, which causes the Al liquid on the surface of the molten steel to be rapidly oxidized and lose the deoxidation ability to become Al2O3 and enter the slag.

[0070] (2) The deoxidation product Al2O3 is difficult to be removed from the molten steel.

[0071] (3) Steel [Al2O3] inclusion removal is collision, aggregation and growth and through the liquid steel stirring movement to make it float and be absorbed by the top slag exclusion process, under the condition of single Al deoxidation, the deoxidation product generated in the liquid steel is mainly solid [Al2O3] particles, Al2O3 melting point is as high as 2054℃, density 3.5g / cm 3 , at steelmaking temperature, solid Al2O3 particles are very difficult to be removed from the liquid steel, if not removed from the liquid steel in time, the larger size remaining in the steel will form brittle inclusions, which is harmful to the quality of the steel.

[0072] To improve the quality of Q195 products, deoxidation must be enhanced, and increasing the amount of Al alone has caused poor liquid steel flowability, slab continuous casting casting difficulties and multiple nozzle clogging accidents, causing great difficulty in actual production.

[0073] Problems in the user's processing process of our company's Q195 strip steel: cold stamping processing into 2 pieces, strip steel edge breakage, insufficient deoxidation depth, and porosity in cast slab. In actual production, if only the amount of Al is increased for deoxidation, continuous casting cannot be normally cast, and only increasing deoxidation will cause a significant decrease in liquid steel flowability, and continuous casting of slabs frequently appears to be clogged or even dead, resulting in normal production. However, the reality is that the demand for strip steel products in the market is relatively good, which is easier to achieve sales, capital return and normal production and operation of enterprises. Therefore, while enhancing deoxidation, measures must be taken to ensure that most of the deoxidation products Al2O3 are removed from the liquid steel, to ensure the flowability of the liquid steel and the normal production of continuous casting of slabs.

[0074] Therefore, by adopting innovative composite deoxidation, any one phase of the composite phase is formed, and the deoxidation product is changed into a liquid state. As long as the liquid deoxidation product is formed, it can be easily removed from the liquid steel by blowing Ar stirring, which can ensure the deoxidation depth and cleanliness, improve the castability of the liquid steel, realize stable production of continuous casting of slabs, and improve the quality of Q195 strip steel.

[0075] The cost of deoxidation and alloying of slab Q195 is reduced. According to the on-site investigation, the amount of Al used in the production of slab continuous casting Q195 by external factories is as high as 1.2-1.5 kg / t, and the average cost after slag washing and Ca treatment is about 32.39 yuan / t. The cost of innovative composite deoxidation process is about 20.2 yuan / t, which is about 12.19 yuan / t lower than that of external factories. From January to November 2023, a total of 128.92 million tons of slabs were smelted and produced, of which 87.94 million tons of Q195 slabs were produced. According to the calculation of 12.19 yuan / t lower than that of external factories per ton of steel, the cost of Q195 slab steel produced by Xianfu Steel is 1071.985 million yuan lower than that of external factories of the same grade steel.

[0076] While the application has been described with reference to numerous exemplary embodiments, it will be understood that various other modifications can be made within the scope of the application as disclosed herein. More particularly, many modifications can be made to the components and / or arrangements of the subject combinations within the scope and spirit of the disclosure and claims. In addition those skilled in the art will recognize or be able to ascertain using no more than routine experimentation many equivalents to the specific embodiments described herein. It is therefore to be understood that any embodiments disclosed herein are merely illustrative of the principles of the present application and that various modifications can be made by those skilled in the art which will accomplish like results.

Claims

1. A method for smelting and deoxidizing Q195 steel slabs, characterized in that: Includes the following steps: Step 1) Add molten iron and scrap steel to the converter and smelt using a nitrogen-argon combined blowing mode; Step 2) When the steel is tapped, the composite deoxidizing material is added according to the proportion. The steel is then refined by impacting, mixing and blowing Ar to complete the deoxidation and alloying. The composite deoxidizing material includes: deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, and FeSi alloy; the proportions of each substance are as follows: deoxidizer 3.5-5.5 kg / t, BaCaAlSi 0.55-1.0 kg / t, aluminum block 0.36-0.87 kg / t, MnSi alloy 0.6-2.5 kg / t, and FeSi 0.36-0.88 kg / t. Step 3) Cast the molten steel obtained in Step 2) into slabs using continuous casting. In step 2), deoxidation alloying includes the following steps: Step 2.1) Control the alloying process to achieve the final smelting requirements for Q195 steel slabs; Step 2.2) When the molten steel reaches 1 / 3 of the ladle, add composite deoxidizing material for deoxidation and alloying, and at the same time, blow Ar and stir the molten steel for refining. Step 2.3) Slag blocking during steel tapping is achieved by using a slag blocking trolley for positioning and blocking, controlling the slag discharge amount to ≤80mm; Step 2.4) After the deoxidation and alloying of the steel is completed, the ladle is subjected to Ar blowing refining and stirring. During stirring, the composition of the molten steel, oxygen activity, and temperature of the molten steel are adjusted, and the intensity of Ar blowing and stirring time are controlled. Step 2.5) Once the Ar refining and stirring composition, oxygen activity, temperature, and time meet the process control requirements, the slab can be continuously cast. Step 3) of the slab continuous casting process includes the following steps: Slab continuous casting is carried out in accordance with the requirements of full protective casting, which includes casting with protective slag from the ladle long nozzle, the tundish immersion nozzle and the mold mold flux. For ladle casting, a long nozzle is required for protection during casting. The long nozzle is inserted into the liquid surface of the tundish 180-250mm. The tundish is filled with liquid during operation. Tundish casting uses a segmented immersion nozzle, which is inserted into the crystallizer 110-135mm. The liquid surface in the crystallizer is protected by a special crystallizer protective slag during casting.

2. The smelting and deoxidation method for Q195 slab steel according to claim 1, characterized in that: In step 1), the smelting process includes the following steps: Step 1.1) The converter is loaded with water in stages and in fixed quantities according to the furnace service life and the furnace chamber; Step 1.2) Charge the converter with molten iron and scrap steel; by weight percentage: molten iron 80-85%, scrap steel 15-20%; Step 1.3) The slab Q195 steel is smelted using a nitrogen-argon combined blowing mode during the smelting process. The final composition of the slab Q195 steel is controlled as C≤0.06%, P≤0.025%, and S≤0.030%.

3. The smelting and deoxidation method for Q195 slab steel according to claim 2, characterized in that: The molten iron has a C content ≥3.60%, a Si content 0.08~0.65%, a P content ≤0.150%, a S content ≤0.040%, and an As content ≤0.060%.

4. The smelting and deoxidation method for Q195 slab steel according to claim 2, characterized in that: The temperature of the molten iron is 1200–1350℃.

5. The smelting and deoxidation method for Q195 slab steel according to claim 2, characterized in that: The tapping temperature is 1615–1665℃.

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