CN105734419B - A kind of V, Ti micro alloyed steel and its smelting process and purposes - Google Patents

Abstract

The invention belongs to the field of iron and steel smelting, and in particular relates to a V and Ti micro-alloy steel and its smelting method and application. In the prior art, metal deoxidation materials are mostly used as deoxidation materials in steelmaking, and the cost of deoxidation is high. The present invention provides a smelting method that can reduce the cost of steelmaking, including converter steelmaking, small platform furnace external treatment and continuous casting steps, converter steelmaking The new deoxidation alloying process is adopted in the stage, and the outbound oxygen activity of the small platform is controlled to be ≤50ppm in the stage of small platform furnace treatment, so as to produce V and Ti microalloy steels. The invention saves the amount of metal deoxidation materials used, introduces V and Ti microalloys at the same time, reduces the addition of silicon and manganese, saves costs, and the steel produced can meet the performance requirements of construction steel.

Description

A kind of V, Ti microalloy steel and its smelting method and application

technical field

The invention belongs to the field of iron and steel smelting, and in particular relates to a V and Ti microalloy steel and its smelting method and application.

Background technique

Plain carbon steel is the main type of steel in my country's iron and steel industry and plays an important role in the development of the national economy. According to statistics, the proportion of ordinary carbon steel plate in the plate is more than 70%. Construction steel is a kind of ordinary carbon steel. Generally, the strength, toughness and plasticity of the steel plate are not high. It only needs to meet the mechanical properties of the national standard GB/T700-2006 for general ordinary carbon steel. Yield strength ≥ 235Mpa; tensile strength 370-500Mpa; elongation after breaking ≥ 26%.

There have been some domestic research results on the industrial production and product application of Q235 low-alloy high-strength structural steel. For example, in the document "Wu Haohong. Performance and cost optimization of Q235B thin plate on CSP line of Lianyuan Iron and Steel Co., Ltd. [J]. Metal Materials and Metallurgical Engineering, 2010, June, 34-38." After adjustment, the content of Mn, the element that controls the strength of the steel, is mainly adjusted to 0.28-0.38%. The performance of the finished product fully meets the national standard and the needs of users. The Mn content in Q235 low-alloy high-strength structural steel such as Jiugang and Wuhan Iron and Steel is generally above 0.35%. In order to ensure that the strength of Q235 low-alloy high-strength structural hot-rolled steel sheets meets the standard requirements, the content of the main alloying element Mn is basically controlled at a relatively high level above 0.35%, resulting in high production costs.

The production cost of steelmaking in the prior art is high, how to reduce the content of Si and Mn which have great influence on the strength of steel so as to make the steel to achieve the required mechanical properties has very important practical significance for saving production cost.

Contents of the invention

For the problems existing in the above-mentioned prior art, the purpose of the invention of the present invention is to provide a kind of V, Ti microalloy steel and its smelting method and application, the method can produce vanadium, titanium microalloy steel with Panzhihua Iron and Steel characteristics, by adding Ferro-vanadium and ferro-titanium provide V and Ti microalloys, thereby reducing the content of silicon and manganese. On the basis of meeting the national standard for mechanical properties, it greatly reduces the cost of steelmaking and has good economic benefits.

The first technical problem to be solved by the present invention is to provide a kind of V, Ti microalloy steel, its composition is: by weight percentage, C: 0.20～0.25, Si: 0.03～0.08, Mn: 0.10～0.15, P: 0 to 0.035, S: 0 to 0.035, V: 0.01 to 0.05%, Ti: 0.01 to 0.05%, Cr: 0 to 0.03%, Ni: 0 to 0.03%, and the balance is Fe and unavoidable impurities.

Among them, the above-mentioned V and Ti microalloy steels preferably have the following components: by weight percentage, C: 0.21-0.24, Si: 0.04-0.07, Mn: 0.11-0.14, P: 0-0.025, S: 0 ～0.025, V: 0.02～0.04%, Ti: 0.02～0.04%, Cr: 0～0.02%, Ni: 0～0.02%, and the balance is Fe and unavoidable impurities.

Wherein, the above-mentioned V and Ti micro-alloy steels are produced by the following smelting methods, including converter steelmaking, small platform out-of-furnace treatment and continuous casting steps. The deoxidation alloying process in the converter steelmaking stage is: When the content is ≤0.04%, add carbon powder and carburizer for pre-deoxidation when the molten steel covers the bottom of the ladle tank, and then add carburant, Composite deoxidizer and silicon-manganese alloy, after tapping, add ferro-vanadium and ferro-titanium; when the carbon content at the end point of converter smelting molten steel is > 0.04%, add directly when the tapping weight accounts for 1/3 to 1/2 of the total weight Carbon agent, composite deoxidizer, and silicon-manganese alloy, after tapping, add ferrovanadium and ferrotitanium; in the small platform furnace out-of-furnace treatment stage, control the oxygen activity of the small platform to ≤50ppm.

The second technical problem to be solved by the present invention is to provide a method for smelting V and Ti microalloy steels, which includes the steps of converter steelmaking, small platform furnace treatment and continuous casting;

The deoxidation alloying process in the converter steelmaking stage is as follows: when the carbon content at the end point of the converter smelting molten steel is ≤0.04%, when the molten steel covers the bottom of the ladle tank, first add carbon powder and carburizer for pre-deoxidation, and the weight of the steel after tapping accounts for the total When the weight is 1/3~1/2, then add recarburizer, composite deoxidizer and silicon-manganese alloy in sequence, after tapping, add ferrovanadium and ferrotitanium; When the tapping weight accounts for 1/3 to 1/2 of the total weight, directly add recarburizer, composite deoxidizer and silicon-manganese alloy. After tapping, add ferrovanadium and ferrotitanium;

The outbound oxygen activity of the small platform is controlled to be less than or equal to 50ppm in the small platform furnace treatment stage.

Wherein, in the above-mentioned smelting method of V and Ti micro-alloy steels, the amount of carbon powder added is 0.15-0.30 kg/t steel.

Wherein, in the above-mentioned smelting method of V and Ti microalloy steels, the addition amount of the recarburizer is as follows: when the carbon content is ≤0.04, the recarburizer is added for the first time at 0.2-0.5 kg/t steel, and the second time is added with the recarburizer. Carbon agent 2.1~2.8kg/t steel; when carbon content>0.04%, add carburizer 2.2~2.6kg/t steel.

Wherein, in the above-mentioned smelting method of V and Ti microalloy steel, the composite deoxidizer is a composite deoxidizer of 60-65wt% CaC2 and _28-34wt % Si, and the addition amount is 1.4-1.6kg/t steel.

Wherein, in the above-mentioned deoxidation alloying method of V and Ti microalloy steels, the particle size of the composite deoxidizer is 15-20 mm.

Wherein, in the smelting method of the above-mentioned V and Ti microalloy steel, the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, and the addition amount is 2.1-2.4kg/t steel .

Wherein, in the smelting method of the above-mentioned V and Ti microalloy steel, the added amount of the ferrovanadium is 0.7-0.95kg/t steel, and the ferrovanadium is ferrovanadium with a V content of 50%.

Wherein, in the above-mentioned smelting method of V and Ti microalloy steels, the added amount of ferrotitanium is 1.2-1.45kg/t steel, and the ferrotitanium is ferrotitanium with a Ti content of 30%.

The third technical problem to be solved by the present invention is to provide a use of the above-mentioned V and Ti micro-alloyed steel for the construction industry and the pipe industry.

The beneficial effect of the present invention is: the present invention provides a kind of V, Ti microalloy steel and its deoxidation alloying method and application thereof, the method adopts low-cost steelmaking deoxidation alloying process, uses carbon powder to carry out pre-deoxidation earlier, reduces The amount of metal deoxidation materials used also avoids the pollution of molten steel by metal deoxidation products; at the same time, after deoxidation, ferrovanadium and ferrotitanium are added for alloying treatment, and the addition of V and Ti microalloys reduces the addition of silicon and manganese. The cost of steelmaking has been greatly reduced, so that vanadium and titanium microalloy steels with Panzhihua's characteristics can be produced. While reducing costs, the steel can fully meet the mechanical performance requirements of the national standard GB/T 700-2006, and can be mainly used in construction and plumbing.

detailed description

The invention provides a V and Ti micro-alloy steel, the composition of which is: by weight percentage, C: 0.20-0.25, Si: 0.03-0.08, Mn: 0.10-0.15, P: 0-0.035, S: 0-0.035 , V: 0.01-0.05%, Ti: 0.01-0.05%, Cr: 0-0.03%, Ni: 0-0.03%, and the balance is Fe and unavoidable impurities.

Among them, the above-mentioned V and Ti microalloy steels preferably have the following components: by weight percentage, C: 0.21-0.24, Si: 0.04-0.07, Mn: 0.11-0.14, P: 0-0.025, S: 0 ～0.025, V: 0.02～0.04%, Ti: 0.02～0.04%, Cr: 0～0.02%, Ni: 0～0.02%, and the balance is Fe and unavoidable impurities.

Wherein, the above-mentioned V and Ti microalloy steels are produced by the following smelting methods, including converter steelmaking, small platform out-of-furnace treatment and continuous casting steps, and the deoxidation alloying process in the converter steelmaking stage is: When the carbon content is ≤0.04%, add carbon powder and carburizer for pre-deoxidation when the molten steel covers the bottom of the ladle tank, and then add carburizer in turn when the tapping weight accounts for 1/3 to 1/2 of the total weight , compound deoxidizer and silicon-manganese alloy, after tapping, add ferrovanadium and ferrotitanium; when the carbon content at the end point of converter smelting molten steel is >0.04%, add it directly when the tapping weight accounts for 1/3-1/2 of the total weight Carburizers, composite deoxidizers and silicon-manganese alloys are added to ferro-vanadium and ferro-titanium after tapping; the out-of-station oxygen activity of the small platforms is controlled to be ≤ 50ppm in the small platform furnace treatment stage.

The present invention also provides a method for smelting V and Ti microalloy steels, comprising the steps of converter steelmaking, small platform furnace treatment and continuous casting;

The deoxidation alloying process in the converter steelmaking stage is as follows: when the carbon content at the end point of the converter smelting molten steel is ≤0.04%, when the molten steel covers the bottom of the ladle tank, first add carbon powder and carburizer for pre-deoxidation, and the weight of the steel after tapping accounts for the total When the weight is 1/3~1/2, then add recarburizer, composite deoxidizer and silicon-manganese alloy in sequence, after tapping, add ferrovanadium and ferrotitanium; When the tapping weight accounts for 1/3 to 1/2 of the total weight, directly add recarburizer, composite deoxidizer and silicon-manganese alloy. After tapping, add ferrovanadium and ferrotitanium;

The outbound oxygen activity of the small platform is controlled to be less than or equal to 50ppm in the small platform furnace treatment stage.

Among them, in order to achieve the pre-deoxidation effect, when the carbon content of the end point of the converter smelting molten steel is ≤0.04%, first add 0.15-0.30kg/t steel carbon powder. The present invention uses carbon powder as a non-metal deoxidation material for deoxidation, which can significantly reduce the amount of metal deoxidation material. The deoxidation efficiency of carbon powder and the deoxidation efficiency of pure aluminum can be converted by 1:1. By promoting the use of converter carbon deoxidation technology, relatively Based on the original smelting process for producing ordinary carbon steel, it not only reduces the amount of metal deoxidation materials, but also reduces the pollution of metal deoxidation products to molten steel.

In order to adjust the carbon content of molten steel at the end of smelting, when the carbon content of molten steel at the end of converter smelting is ≤0.04%, two recarburizers should be added. The first addition is mainly to exert the carbon deoxidation effect of the recarburizer, and the second addition is to increase carbon. When the carbon content at the end point of the converter smelting molten steel is >0.04%, it is enough to directly add a recarburizer once. At this time, the recarburizer is mainly used for recarburization of the converter to the steel grade requirement range of C: 0.20-0.25%. Among them, the amount of carburizing agent added is: when the carbon content is ≤0.04, the first time adding carburizing agent is 0.2~0.5kg/t steel, and the second adding carburizing agent is 2.1~2.8kg/t steel; carbon content> 0.04%, add recarburizer 2.2~2.6kg/t steel.

In order to carry out deoxidation better and save cost, the present invention adds composite deoxidizer to carry out deoxidation simultaneously, reduces the consumption of metal deoxidation material, reduces the quantity of inclusion and lowers production cost; Preferred composite deoxidizer among the present invention consists of: CaC ₂ 60-65wt%, Si 28-34wt%, the balance Fe, the addition amount is 1.4-1.6kg/t steel. At the same time, the particle size of the deoxidizer will affect the deoxidation effect. In the present invention, the particle size of the deoxidizer is limited within the range of 15-20 mm, which can effectively ensure the deoxidation effect.

In order to obtain high-strength steel, it is necessary to add an appropriate amount of silicon-manganese alloy. In the present invention, since ferrovanadium and ferro-titanium are added in the later stage, the amount of silicon-manganese alloy added can be effectively reduced. The preferred amount of silicon-manganese alloy added is 2.1-2.4kg /t steel, the composition of the silicon-manganese alloy is: by weight percentage, Mn: 60.0-67.0%, Si: 14.0-17.0%, C: ≤2.5%, P: ≤0.2%, S: ≤0.2%, and The amount is Fe.

In particular, the present invention adds ferrovanadium and ferrotitanium to make steel, and the amount of ferrovanadium added is 0.7-0.95kg/t steel, preferably ferrovanadium with a V content of 50%, but it is not limited to limit the V content within this range, according to The amount of ferro-vanadium is adjusted according to the difference in V content; the amount of ferro-titanium added is 1.2-1.45kg/t steel, preferably ferro-titanium with a Ti content of 30%, but it is not limited to limit the Ti content within this range, according to the Ti content The difference to adjust the amount of ferro-titanium added.

Continuous casting is continuous casting. It is a casting process in which molten steel continuously passes through a water-cooled crystallizer during steelmaking, condenses into a hard shell, and is continuously pulled out from the outlet below the crystallizer. After being cooled by water spray, it is completely solidified and then cut into billets. In the smelting method of the present invention, the continuous casting is carried out by a conventional continuous casting method.

The technical solutions of the present invention will be further described below in conjunction with the examples, but it does not mean that the scope of protection is limited to the scope of the examples.

The products used in the examples are common commercially available products.

Example 1

120t converter steelmaking, 133t steel tapping. The carbon content at the end point of smelting molten steel is 0.03%. During the tapping process, when the molten steel covers the bottom of the ladle tank, 0.20kg/t steel carbon powder and 0.3kg/t steel recarburizer are added for pre-deoxidation, and the carbon-oxygen reaction in the ladle is required. After calming down (approximately 1/3~1/2 of tapping), add recarburizer, composite deoxidizer and SiMn alloy in order, among which 2.6kg/t steel is added to recarburizer, 1.5kg/t steel is added to composite deoxidizer t steel, silicon manganese is added quantitatively at 2.2kg/t steel. The outbound oxygen activity of the small platform is 30ppm, the addition amount of FeTi30-A is 1.36kg/t steel, and the addition amount of FeV50-A is 0.83kg/t steel. Continuous casting is carried out after the small platform leaves the station, and the steel composition after the final product is: C: 0.23, Si: 0.06, Mn: 0.13, P: 0.025, S: 0.015, V: 0.03%, Ti: 0.03%, Cr: 0.015%, Ni: 0.015%, the balance being Fe and unavoidable impurities.

Final properties: yield strength: 337MPa, tensile strength: 427MPa, elongation after break: 36%. The V and Ti microalloy steels produced fully meet the national standards and user requirements.

Example 2

120t converter steelmaking, 135t steel tapping. The carbon content at the end point of smelting molten steel is 0.07%. After the carbon-oxygen reaction in the ladle tends to calm down during the tapping process (about 1/3 to 1/2 of the tapping), add carburizers, composite deoxidizers, and SiMn alloys in sequence, among which A total of 2.45kg/t steel is added to the carburizer, 1.4kg/t steel is added to the composite deoxidizer, and 2.1kg/t steel is added quantitatively to silicon manganese. The outbound oxygen activity of the small platform is 28ppm, the addition amount of FeTi30-A is 1.25kg/t steel, and the addition amount of FeV50-A is 0.75kg/t steel. Continuous casting is carried out after the small platform leaves the station, and the steel composition after the final product is: C: 0.21, Si: 0.045, Mn: 0.13, P: 0.020, S: 0.014, V: 0.02%, Ti: 0.02%, Cr: 0.014%, Ni: 0.021%, the balance being Fe and unavoidable impurities.

Final properties: yield strength: 341MPa, tensile strength: 432MPa, elongation after break: 40%. The V and Ti microalloy steels produced fully meet the national standards and user requirements.

Example 3

120t converter steelmaking, the steel output is 134t. The carbon content at the end point of smelting molten steel is 0.06%. After the carbon-oxygen reaction in the ladle tends to be calm during the tapping process (about 1/3~1/2 of tapping), add carburizer, composite deoxidizer and SiMn alloy in sequence, among which A total of 2.6kg/t steel is added to the carburizer, 1.6kg/t steel is added to the composite deoxidizer, and 2.35kg/t steel is added quantitatively to silicon manganese. The outbound oxygen activity of the small platform is 34ppm, the addition amount of FeTi30-A is 1.4kg/t steel, and the addition amount of FeV50-A is 0.9kg/t steel. Continuous casting is carried out after the small platform leaves the station, and the steel composition after the final product is: C: 0.23, Si: 0.08, Mn: 0.14, P: 0.019, S: 0.012, V: 0.035%, Ti: 0.035%, Cr: 0.016%, Ni: 0.028%, the balance being Fe and unavoidable impurities.

Final properties: yield strength: 326MPa, tensile strength: 441MPa, elongation after break: 42%. The V and Ti microalloy steels produced fully meet the national standards and user requirements.

It can be seen from the examples that the present invention utilizes ferrovanadium and ferrotitanium to provide V and Ti microalloys, adding a small amount of V and Ti in molten steel will form part of TiC and VC, and fine dispersed particles will be precipitated in the rolling and cooling process. TiC and VC can effectively prevent the movement of dislocations and play a strong precipitation strengthening effect. A small amount of vanadium and titanium can make up for the influence of the strength caused by the reduction of manganese content. Through the strengthening method of vanadium and titanium microalloying, the ordinary carbon steel maintains good mechanical properties, which not only increases the strength of the steel, but also saves silicon. The addition of manganese alloy reduces the production cost, and the mechanical properties of the produced microalloy steel meet the requirements of the national standard GB/T700-2006, which can be mainly used in the construction industry and the pipe industry.

Claims (25)

1. a method for smelting V, Ti microalloy steel, comprising converter steelmaking, small platform furnace external treatment and continuous casting steps, characterized in that: The deoxidation alloying process in the converter steelmaking stage is as follows: when the carbon content at the end point of the converter smelting molten steel is ≤0.04%, when the molten steel covers the bottom of the ladle tank, first add carbon powder and carburizer for pre-deoxidation, and the weight of the steel after tapping accounts for the total When the weight is 1/3~1/2, then add recarburizer, composite deoxidizer and silicon-manganese alloy in sequence, after tapping, add ferrovanadium and ferrotitanium; When the tapping weight accounts for 1/3 to 1/2 of the total weight, directly add recarburizer, composite deoxidizer and silicon-manganese alloy. After tapping, add ferrovanadium and ferrotitanium; The outbound oxygen activity of the small platform is controlled to be less than or equal to 50ppm in the small platform furnace treatment stage; The composition of the V and Ti micro-alloyed steel is: by weight percentage, C: 0.20-0.25%, Si: 0.03-0.08%, Mn: 0.10-0.15%, P: 0-0.035%, S: 0-0.035% , V: 0.01-0.05%, Ti: 0.01-0.05%, Cr: 0-0.03%, Ni: 0-0.03%, and the balance is Fe and unavoidable impurities. 2. The method for smelting V and Ti micro-alloyed steels according to claim 1, characterized in that: the amount of carbon powder added is 0.15-0.30 kg/t of steel. 3. The method for smelting V and Ti microalloyed steels according to claim 1 or 2, characterized in that: the amount of the recarburizer added is: when the carbon content is ≤0.04%, add 0.2% of the recarburizer for the first time ~0.5kg/t steel, add carburant 2.1~2.8kg/t steel for the second time; when carbon content>0.04%, add carburant 2.2~2.6kg/t steel. 4. The method for smelting V and Ti microalloyed steels according to claim 1, characterized in that: the composite deoxidizer is a composite deoxidizer of CaC ₂ 60-65wt%, Si 28-34wt%, and the addition amount is 1.4 ~1.6kg/t steel. 5. The method for smelting V and Ti microalloyed steels according to claim 2, characterized in that: said composite deoxidizer is a composite deoxidizer of CaC ₂ 60-65wt%, Si 28-34wt%, and the addition amount is 1.4 ~1.6kg/t steel. 6. The method for smelting V and Ti microalloy steels according to claim 3, characterized in that: the composite deoxidizer is a composite deoxidizer of CaC ₂ 60-65wt%, Si 28-34wt%, and the addition amount is 1.4 ~1.6kg/t steel. 7. The method for smelting V and Ti micro-alloyed steel according to claim 1, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 8. The method for smelting V and Ti micro-alloyed steel according to claim 2, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 9. The method for smelting V and Ti microalloyed steel according to claim 3, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 10. The method for smelting V and Ti micro-alloyed steel according to claim 4, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 11. The method for smelting V and Ti micro-alloyed steels according to claim 5, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 12. The method for smelting V and Ti micro-alloyed steels according to claim 6, characterized in that: the silicon-manganese alloy is a silicon-manganese alloy of Mn: 60.0-67.0wt%, Si: 14.0-17.0wt%, adding The amount is 2.1~2.4kg/t steel. 13. The method for smelting V and Ti micro-alloyed steel according to claim 1, characterized in that: the ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 14. The method for smelting V and Ti micro-alloyed steel according to claim 2, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 15. The method for smelting V and Ti micro-alloyed steel according to claim 3, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 16. The method for smelting V and Ti micro-alloyed steel according to claim 4, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 17. The method for smelting V and Ti micro-alloyed steel according to claim 5, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 18. The method for smelting V and Ti micro-alloyed steel according to claim 6, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 19. The method for smelting V and Ti micro-alloyed steel according to claim 7, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 20. The method for smelting V and Ti micro-alloyed steel according to claim 8, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 21. The method for smelting V and Ti micro-alloyed steel according to claim 9, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 22. The method for smelting V and Ti micro-alloyed steel according to claim 10, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 23. The method for smelting V and Ti micro-alloyed steel according to claim 11, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 24. The method for smelting V and Ti micro-alloyed steel according to claim 12, characterized in that: said ferrovanadium is ferrovanadium with a V content of 50%, and the addition amount is 0.7-0.95kg/t steel. 25. The method for smelting V and Ti microalloyed steel according to any one of claims 1-2, 4-24, characterized in that: the ferrotitanium is ferrotitanium with a Ti content of 30%, and the addition amount is 1.2 ~1.45kg/t steel.