Smelting deoxidation method for slab Q195 steel

Abstract

The invention discloses a smelting deoxidation 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 an N2-Ar combined blowing mode; (2) adding a composite deoxidizing material according to the proportion in tapping, impacting and mixing by virtue of tapping steel flow, blowing Ar, stirring and refining, and completing deoxidizing alloying; and (3) the molten steel obtained in the step (2) is subjected to slab continuous casting. While the deoxidation is enhanced, measures are taken to ensure that most of high-melting-point deoxidation products Al2O3 and deoxidation products of Ca, Si and Mn form a low-melting-point composite phase, and the low-melting-point composite phase is in a liquid state at the steelmaking temperature and is easily discharged from molten steel during Ar blowing, stirring and refining, so that the cleanliness of the molten steel is improved, the liquidity of the molten steel is ensured, and normal production of slab continuous casting is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of steelmaking, and in particular to a slab Q195 steel smelting and deoxidation method. Background Art

[0002] All plate and strip products are processed materials. Strip steel must be processed into different products on various user processing lines before it can be used in various industries. The downstream users of hot-rolled Q195 strip steel, which consumes the most, are mainly pickling and cold rolling, galvanizing, cold forming, cold stamping, bending and pipe making, coiling, cutting and welding to make steel components, and so on. The strip steel product processing process is a process of repeated inch-by-inch inspection of product quality. Any defects in the product will be apparent during processing and cause objections. Strip steel production control requirements are higher than those of general building materials. Strip steel market competitiveness is mainly based on quality, while the production of general building materials focuses on economic efficiency. Q195 slabs are prone to substandard deoxidation depth, resulting in unstable cold bending and cold working performance, affecting user product quality and causing losses.

[0003] Deoxidation of slab Q195 is crucial in smelting and is a key step in determining product quality. While strengthening deoxidation, measures must be taken to ensure that most of the deoxidation product Al2O3 is removed from the molten steel to ensure the fluidity of the molten steel and the normal production of slab continuous casting. Our company's original deoxidation process only used Al blocks for deoxidation. The single Al block deoxidation produced a large amount of high-melting-point flocculent deoxidation Al2O3 products, which could not be effectively removed from the molten steel in the current process. The water sluice problem frequently occurred during casting, resulting in the oxygen content of the molten steel failing to meet the requirements. Observation showed that the relative density of the Al block was relatively low, only 2.7g / cm 3 The deoxidizing Al blocks added during converter tapping float on the surface of the hot molten steel. Even after melting into Al liquid, they still float on the surface. Deoxidation can only be achieved by the impact and mixing of the tapping steel stream to allow the Al liquid to contact the hot, highly oxidizing molten steel. However, it is quite difficult to achieve complete deoxidation of the entire molten steel in a short tapping time and meet the required standards. During tapping, some molten steel is incompletely or unevenly deoxidized. Although Ar is blown from the bottom of the ladle to stir the molten steel, a small amount of highly oxidizing final slag will occur in the later stage of tapping. As a result, the Al liquid floating on the surface of the molten steel is quickly oxidized, losing its deoxidizing ability and turning into Al2O3 that enters the slag. The Al2O3 generated by the part of Al that has completed the deoxidation task has a high melting point of 2050℃ and remains in the steel as dispersed, fine, solid flocculent oxides. It is very difficult to discharge from the molten steel. As a result, the high-melting-point Al2O3 precipitates out of the molten steel during casting and sticks to the nozzle, causing sludging. This makes the slab process extremely unstable. The single Al deoxidation process is not suitable for the company's current process. Summary of the Invention

[0004] The purpose of the present invention is to provide a smelting and deoxidation method for slab Q195 steel, so as to solve the problems of poor fluidity of molten steel, difficulty in casting due to nozzle clogging, and inability to cast, and multiple nozzle clogging and forced casting to be stopped when the slab is continuously cast and the amount of Al used for deoxidation is increased.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A smelting and deoxidation method for slab Q195 steel comprises the following steps:

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

[0008] Step 2) Add composite deoxidation materials according to the proportion of steel tapping, rely on steel flow impact, mixing and Ar blowing stirring refining to complete deoxidation and alloying;

[0009] The composite deoxidizing materials include: deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, FeSi alloy; the addition ratio of each material is: deoxidizer 3.5-5.5kg / t, BaCaAlSi 0.55-1.0kg / t, aluminum block 0.36-0.87kg / t, MnSi alloy 0.6-2.5kg / t, FeSi 0.36-0.88kg / t,

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

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

[0012] Step 1.1) The converter is quantitatively charged in stages according to the service life and furnace;

[0013] Step 1.2) The converter is charged with molten iron and scrap steel; in terms of weight percentage, the molten iron is 80-85%, and the scrap steel is 15-20%;

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

[0015] Furthermore: 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] Furthermore: the temperature of the molten iron is 1200-1350°C.

[0017] Furthermore: the tapping temperature is 1615-1665°C.

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

[0019] Step 2.1) Control the slab Q195 steel smelting endpoint requirements to perform steel tapping, deoxidation, and alloying;

[0020] Step 2.2) When the molten steel reaches 1 / 3 of the ladle, a composite deoxidizing material is added for deoxidation and alloying. At the same time, Ar is blown into the molten steel to stir and remove deoxidation products to improve the cleanliness of the molten steel;

[0021] Step 2.3) Use a slag stop trolley to position the slag during tapping, and control the slag volume to be ≤80mm;

[0022] After the steel is tapped and deoxidized and alloyed in step 2.4), the ladle is subjected to Ar blowing and stirring refining. During stirring, the composition, oxygen activity, and temperature of the molten steel are adjusted. Simultaneously, an optimized Ar blowing and stirring process is implemented during the Ar blowing and stirring process to promote the collision, aggregation, and growth of high-melting-point Al2O3 deoxidation products with deoxidized oxides of calcium, silicon, and manganese, forming a low-melting-point composite phase (liquid). Under optimized Ar blowing and stirring driving conditions, the composite phase is discharged from the molten steel into the ladle top slag, thereby improving the cleanliness of the molten steel and reducing the problem of sludging caused by the high-melting-point Al2O3 phase precipitated from the molten steel during the casting process and adhering to the nozzle wall. The Ar blowing intensity and stirring time are controlled.

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

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

[0025] Slab continuous casting is carried out according to the full protection casting requirements, which include the long shroud of the large ladle, the immersion shroud of the middle ladle and the protection casting of the mold slag to prevent the molten steel from generating air absorption and secondary oxidation;

[0026] Large ladle casting requires a long nozzle to protect the casting. The long nozzle is inserted into the tundish liquid level 180-250mm, and the tundish is operated with the liquid level full. The tundish casting adopts a segmented immersion nozzle, which is inserted into the crystallizer 110-135mm. The crystallizer liquid level is protected by a special mold protection slag for casting;

[0027] Slab continuous casting strictly implements the three stability control rules of "stable tundish temperature, stable control of casting speed, and stable control of crystallizer liquid level" to produce qualified castings.

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

[0029] (1) While enhancing deoxidation, measures are taken to ensure that most of the high-melting-point deoxidation products Al2O3 and the deoxidation products of Ca, Si, and Mn form a low-melting-point composite phase. The low-melting-point composite phase is liquid at the steelmaking temperature, which is conducive to its removal from the molten steel, thereby improving the cleanliness of the molten steel, ensuring the fluidity of the molten steel, and guaranteeing the normal production of slab continuous casting.

[0030] (2) The independent innovation of composite deoxidation process in steelmaking has greatly reduced the production cost of strip steel.

[0031] (3) Composite deoxidation mainly uses four deoxidizing elements, Ca, Al, Si, and Mn, for deoxidation at the same time. The deoxidation products formed are CaO, Al2O3, SiO2, and MnO. These four deoxidation products are very easy to collide and aggregate under the impact of steel flow, mixing and Ar blowing to form a low-melting point composite phase. The low-melting point deoxidation products are liquid at the steelmaking temperature. The liquid inclusions are easily floated and removed from the steel through Ar blowing and stirring refining, thereby reducing the deoxidation inclusions remaining in the steel while ensuring the deoxidation depth, improving the cleanliness of the steel and ensuring the fluidity of the steel, and realizing stable control of slab continuous casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a picture of cold stamping cracking of the product prepared in the comparative example of the present invention.

[0033] Figure 2 The product prepared in the comparative example of the present invention has broken edges of the strip.

[0034] Figure 3 The product prepared as a comparative example in the present invention has a pore pattern. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] Example 1:

[0037] A smelting and deoxidation method for slab Q195 steel comprises the following steps:

[0038] Step 1) Add molten iron and scrap steel into the converter and adopt N2→Ar nitrogen and argon combined blowing mode for smelting:

[0039] The converter is charged in stages and in fixed quantities according to the service life and furnace; the converter is charged with molten iron and scrap steel; 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%, and the As is ≤0.060%, and the molten iron temperature is 1200-1350°C; the slab Q195 steel is smelted in a nitrogen-argon combined blowing mode, and the blowing volume is executed according to the set value of the automatic control software to strictly control the nitrogen content in the steel; the end point composition of the slab Q195 steel is controlled, and the end point requirements of the slab Q195 smelting are C content ≤0.06%, P content ≤0.025%, and S content ≤0.030%; the tapping temperature is 1615-1665°C.

[0040] Step 2) Add composite deoxidation materials according to the proportion during steel tapping, and complete deoxidation and alloying by impacting and mixing the steel flow and blowing Ar to stir and refine;

[0041] Control the slab Q195 steel smelting endpoint requirements for steel tapping deoxidation and alloying;

[0042] When the molten steel reaches 1 / 3 of the ladle, composite deoxidation materials are added for deoxidation and alloying. The composite deoxidation materials include: deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, FeSi alloy; at the same time, Ar is blown into the molten steel to stir it evenly, remove deoxidation products, and improve the cleanliness of the molten steel; the slag is positioned by a slag stopper to control the slag volume to ≤80mm; after the deoxidation and alloying of the steel is completed, Ar is blown into the ladle for refining and stirring, and the steel is completed during the Ar blowing refining and stirring process. The liquid composition is adjusted, the oxygen is fixed, the oxygen activity is adjusted, and the temperature of the molten steel is adjusted. At the same time, an optimized Ar blowing refining and stirring process is implemented during the Ar blowing refining and stirring process, which promotes the collision, aggregation and growth of high-melting-point Al2O3 deoxidation products with deoxidation oxides of calcium, silicon and manganese to form a low-melting-point composite phase (liquid). Under the optimized Ar blowing and stirring driving conditions, the composite phase is discharged from the molten steel into the ladle top slag, thereby improving the cleanliness of the molten steel and reducing the problem of sludging caused by the precipitation of high-melting-point Al2O3 phase on the nozzle wall during the casting process.

[0043] During the Ar blowing refining and mixing process at the Ar blowing refining and mixing station, the optimized Ar blowing and mixing process is strictly implemented. The key control points are the Ar blowing gas intensity and the Ar blowing refining and mixing time, which must meet the requirements. When the Ar blowing refining and mixing composition, oxygen activity, temperature, and time meet the process control requirements, the slab can be discharged from the station for continuous casting.

[0044] The molten steel obtained in step 3) is subjected to slab continuous casting;

[0045] Slab continuous casting requires safe, protective casting, including a long shroud for the ladle, an immersion shroud for the tundish, and mold powder protection to prevent aspiration and secondary oxidation of the molten steel. Ladle casting requires a long shroud for protection, inserted 180-250mm above the tundish liquid level, and operated with the tundish fully filled. Tundish casting utilizes a segmented immersion shroud, inserted 110-135mm into the mold, and a dedicated mold powder for protection. Slab continuous casting adheres to the strict "three stability" control principles of "stable tundish temperature, stable casting speed, and stable mold liquid level" to produce qualified slabs.

[0046] The other examples were all operated according to the preparation method in Example 1. The present invention is further described in detail below with reference to the examples, as shown in Table 1.

[0047] Table 1 Process parameters of the embodiment of the present invention

[0048]

[0049]

[0050] As can be seen from Table 1, the slab Q195 steel prepared and produced in each embodiment has low carbon content in the molten steel at the end of smelting, high end temperature, high oxygen content in the steel, and the deoxidizing materials and alloys are relatively increased; the carbon content in the molten steel at the end of smelting is relatively high, the end temperature is relatively low, the oxygen content in the steel is relatively low, and the deoxidizing materials and alloys are relatively reduced; when there is a lot of residue in the ladle during the smelting process and abnormal slag blocking occurs during steel tapping, the addition ratio of the composite deoxidizing material, the stirring time, and the temperature are taken to the upper and lower limits. By adjusting the process, the oxygen content in the steel is better controlled. The slab Q195 steel produced by the process of the present invention reduces cracking during cold stamping, edge breakage of the strip steel, and the appearance of pores in the ingot.

[0051] Composite deoxidation mainly uses four deoxidizing elements, Ca, Al, Si, and Mn, for deoxidation at the same time. The deoxidation products formed are CaO, Al2O3, SiO2, and MnO. These four deoxidation products are very easy to collide and aggregate under the impact of steel flow, mixing and Ar blowing and stirring to form a low-melting point composite phase. In particular, the high-melting point Al2O3 is converted into a low-melting point deoxidation product, which appears in liquid form at the steelmaking temperature. The liquid inclusions can be easily floated and removed from the steel by blowing Ar and stirring, thereby reducing the deoxidation inclusions remaining in the steel while ensuring the deoxidation depth, improving the cleanliness of the steel and ensuring the fluidity of the steel, and realizing stable control of the quality of the slab continuous casting.

[0052] The deoxygenation products formed are:

[0053]

[0054] Composite deoxidation mainly uses four deoxidizing elements, Ca, Al, Si, and Mn, for deoxidation at the same time. The deoxidation products formed are CaO, Al2O3, SiO2, and MnO. These four deoxidation products are very easy to collide and aggregate under the impact of steel flow, mixing and Ar blowing and stirring to form a low-melting point composite phase, which becomes a low-melting point deoxidation product. It is liquid at the steelmaking temperature. The liquid inclusions can be easily floated and removed from the steel by blowing Ar and stirring, thereby reducing the deoxidation inclusions remaining in the steel while ensuring the deoxidation depth, improving the cleanliness of the steel and ensuring the fluidity of the steel, and realizing stable control of slab continuous casting.

[0055] Comparative Example

[0056] Single Al block deoxidation: The Al block deoxidation process first melts into Al liquid or Al film, which comes into contact with the molten steel for deoxidation and floats on the surface of the molten steel. During the tapping process, 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 and comes into contact with the molten steel to produce a deoxidation reaction:

[0057] The deoxygenation process has the following reactions:

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

[0063] 2[Al]+3(FeO)=[Al2O3] 夹杂物 +3Fe

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

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

[0066] The surface tension between [Al2O3] generated after Al deoxidation and the molten steel is very large. The [Al2O3] generated by the initial deoxidation is solid and dispersed in the molten steel in the form of flocs. Some of the fine [Al2O3] particles collide and aggregate into larger-sized deoxidation products under the impact of the steel flow, mixing and Ar blowing, and float to the slag surface under buoyancy and the movement of the molten steel, and are adsorbed by the slag and removed. However, the size of the initially generated [Al2O3] particles is very small, and there are still many that do not collide and aggregate quickly under the action of stirring to form larger-sized deoxidation products and are eliminated. Instead, larger-sized deoxidation products begin to form as time goes by. At this time, the molten steel is already being cast. During the casting process, as the molten steel flows, they come into contact with the stopper rod and the nozzle surface, precipitate and adhere to the stopper rod and the nozzle surface, causing flocculent nozzle problems, which have a great impact on the fluidity of the molten steel.

[0067] The collision, aggregation and growth process of [Al2O3] deoxidation inclusions in steel: The removal of [Al2O3] deoxidation inclusions in steel is a process of collision, aggregation and growth, and the removal of [Al2O3] deoxidation inclusions by blowing Ar into the molten steel and stirring it to float up and be adsorbed by the top slag. Under the condition of single Al deoxidation, the deoxidation products generated in the molten steel are mainly solid [Al2O3] particles. The melting point of Al2O3 is as high as 2054℃ and the density is 3.5g / cm 3 It is solid at the steelmaking temperature. It is quite difficult to remove solid Al2O3 particles from the molten steel. If they are not removed from the molten steel in time, larger ones will remain in the steel to form brittle inclusions, which will cause great harm to the quality of the steel.

[0068] Single Al block deoxidation has the following disadvantages:

[0069] (1) The relative density of Al blocks is relatively low, only 2.7 g / cm 3 The deoxidized Al blocks added during converter tapping float on the surface of the high-temperature molten steel. Even after melting into Al liquid, they still float on the surface. The deoxidation effect can only be achieved by the impact and mixing of the tapping steel flow to allow the Al liquid to contact with the high-temperature, high-oxygen molten steel. However, it is difficult to ensure that all the molten steel is in contact with the Al liquid to produce deoxidation within a short tapping time. During tapping, some molten steel is incompletely or unevenly deoxidized. Although Ar is blown from the bottom of the ladle to stir the molten steel, a small amount of highly oxidizing final slag will appear in the later stage of tapping, causing the Al liquid floating on the surface of the molten steel to be quickly oxidized and lose its deoxidation ability, turning into Al2O3 and entering the slag.

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

[0071] (3) The removal of [Al2O3] inclusions in steel is a process of collision, aggregation, growth, and floating through the stirring movement of the molten steel and adsorption and removal by the top slag. Under the condition of single Al deoxidation, the deoxidation products generated in the molten steel are mainly solid [Al2O3] particles. The melting point of Al2O3 is as high as 2054℃ and the density is 3.5g / cm 3 It is solid at the steelmaking temperature. It is quite difficult to remove solid Al2O3 particles from the molten steel. If they are not removed from the molten steel in time, larger ones will remain in the steel to form brittle inclusions, which will cause great harm to the quality of the steel.

[0072] To improve the quality of Q195 products, deoxidation must be enhanced. However, simply increasing the amount of Al has repeatedly caused poor fluidity of molten steel, difficulty in continuous casting of slabs, and multiple accidents of nozzle clogging that forced casting to be stopped, causing great difficulties in actual production.

[0073] Our Q195 strip steel users have encountered problems during processing, including cracking into two pieces during cold stamping, broken strip edges, and insufficient deoxidation depth leading to pores in the cast slab. In actual production, if only Al is used for enhanced deoxidation in Q195 slab smelting, continuous casting will not function properly. This enhanced deoxidation alone will significantly reduce the fluidity of the molten steel, causing frequent water slugs and even blockages in the slab continuous casting process, resulting in disruptions to normal production. However, the market demand for strip steel products is relatively strong, making it easier to achieve sales, recover capital, and maintain normal production and operations. Therefore, while enhancing deoxidation, measures must be taken to ensure that most of the deoxidation product, Al2O3, is removed from the molten steel to ensure fluidity and maintain normal slab continuous casting production.

[0074] Therefore, we choose to adopt innovative composite deoxidation to promote the deoxidation products to form any phase in the composite phase, and realize the transformation into liquid deoxidation products. As long as the liquid deoxidation products are formed, they can be easily removed from the molten steel by blowing Ar and stirring, thereby ensuring the deoxidation depth and cleanliness while improving the castability of the molten steel, realizing stable production of slab continuous casting, and improving the quality of strip steel Q195.

[0075] Reduced deoxidation and alloying costs for Q195 slabs. According to field investigations, external steelmakers use up to 1.2-1.5 kg / t of aluminum when producing continuous-cast Q195 slabs. After slag washing and Ca treatment, the average cost is approximately 32.39 yuan / t. However, the innovative composite deoxidation process costs approximately 20.2 yuan / t, approximately 12.19 yuan / t lower than external steelmakers. From January to November 2023, smelting production totaled 1.2892 million tons of slabs, including 879,400 tons of Q195 slabs. Calculated at a ton-of-steel cost of approximately -12.19 yuan / t lower than external steelmakers, Xianfu Steel's Q195 slab production costs are 10.71985 million yuan lower than external steelmakers of the same grade.

[0076] Although the present invention has been described herein with reference to a number of illustrative examples thereof, it will be understood that numerous other modifications and implementations may be devised by those skilled in the art that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure and claims, numerous variations and improvements may be made to the components and / or layout of the subject combination arrangement. In addition to variations and improvements to the components and / or layout, other uses will also be apparent to those skilled in the art.

Claims

1. A smelting and deoxidation method for slab Q195 steel, characterized in that: The following steps are involved: Step 1) adding molten iron and scrap steel into a converter and smelting in a nitrogen-argon combined blowing mode; Step 2) Add composite deoxidation materials according to the proportion of steel, rely on steel flow impact, mixing and blowing Ar stirring refining to complete deoxidation and alloying; The composite deoxidation materials include: deoxidizer, BaCaAlSi, aluminum block, MnSi alloy, FeSi alloy; the addition ratio of each material is: deoxidizer 3.5-5.5kg / t, BaCaAlSi 0.55-1.0kg / t, aluminum block 0.36-0.87kg / t, MnSi alloy 0.6-2.5kg / t, FeSi 0.36-0.88kg / t; Step 3) The molten steel obtained in step 2) is subjected to slab continuous casting.

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

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

4. The smelting and deoxidation method of a slab Q195 steel according to claim 2, characterized in that: The temperature of the molten iron is 1200-1350°C.

5. The smelting and deoxidation method of a slab Q195 steel according to claim 2, characterized in that: The steel tapping temperature is 1615-1665°C.

6. The smelting and deoxidation method of a slab Q195 steel according to claim 1, characterized in that: In the step 2), the deoxidation alloying comprises the following steps: Step 2.1) Control the slab Q195 steel smelting end point requirements to perform steel alloying; Step 2.2) When the molten steel reaches 1 / 3 of the ladle, add composite deoxidation materials for deoxidation and alloying. The molten steel is subjected to Ar blowing and stirring refining; Step 2.3) The slag blocking trolley is used to position the slag blocking during steel tapping, and the slag volume is controlled to be ≤80mm; Step 2.4) After the steel is deoxidized and alloyed, the ladle is blown with Ar for refining and stirring. During stirring, the composition of the molten steel, the oxygen activity, and the temperature of the molten steel are adjusted, and the blowing intensity of Ar and the stirring time are controlled; Step 2.5) When the Ar blowing refining and stirring composition, oxygen activity, temperature and time meet the process control requirements, the slab can be continuously cast.

7. The smelting and deoxidation method of a slab Q195 steel according to claim 1, characterized in that: In the step 3), the slab continuous casting comprises the following steps: Slab continuous casting is performed according to the full protection casting requirements, which include long shroud for large ladle, immersion shroud for medium ladle and protection casting of crystallizer slag; Large ladle casting requires a long shroud to protect the casting. The long shroud is inserted into the middle ladle liquid level 180 to 250 mm, and the middle ladle is operated with the liquid level full. The middle ladle casting adopts a segmented immersion shroud, and the immersion shroud is inserted into the crystallizer 110 to 135 mm. The crystallizer liquid level is protected by special crystallizer protective slag for casting.

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