A small square billet sulfur titanium-containing welding wire steel and a preparation method thereof

Abstract

The present application relates to a kind of small square billet sulfur titanium-containing welding wire steel and its preparation method, belong to the technical field of steelmaking.The converter smelting process, refining process and continuous casting process, specifically are as follows:in the converter smelting process, tapping is carried out using aluminum block, ferrosilicon, silicon manganese deoxidation alloying, pre-slagging is carried out by adding lime, after tapping is finished, the total mass content of FeO and MnO in slag is controlled≤2.5%;In the refining process, lime, calcium carbide and aluminum particles are added for slagging and diffusion deoxidation, after slagging is finished, the slag basicity is controlled to be 2.5~3.0, the total mass content of FeO and MnO in slag is≤0.5%, the total oxygen content of molten steel is≤10ppm, sulfur wire and titanium wire are accurately fed;In the continuous casting process, the inclusion is controlled to gather in the stopper head and the water gap bowl by stopper shaking method, and the basicity of protective slag is controlled to be 0.85~0.95.The sulfur titanium-containing welding wire steel prepared by the above method.The present application solves the problems of small square billet sulfur titanium-containing welding wire steel surface slag inclusion, intermediate crack and water gap nodule.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of small billet sulfur-containing titanium-containing welding wire steel and its preparation method, belong to the technical field of steelmaking. BACKGROUND

[0002] Titanium-containing welding wire steel has good covering and low spatter, and has been widely used and popularized in the field of gas shielded welding. However, due to the high Ti content of the steel, a large amount of TiOx is generated during smelting, and is accumulated at the stopper head and the water gap bowl. When small billets are poured, the water gap nodulation problem is more prominent, which seriously affects the continuous casting.

[0003] The patent application with publication number CN104259414A provides a production method of titanium-containing welding wire steel for reducing continuous casting water gap nodulation. By establishing the thermodynamic boundary conditions of aluminum-titanium competitive oxidation, controlling the oxygen activity in the steel, controlling the aluminum and titanium content, determining the titanium-nitrogen product, selecting the water gap refractory and the tundish covering agent, and controlling the continuous casting process parameters, the titanium-containing welding wire steel water gap nodulation is reduced. However, this method does not fundamentally solve the problem of easy accumulation of small-sized inclusions at the stopper head and the water gap bowl of small billets, and the control measures for oxygen content, nitrogen content, aluminum content and calcium content in the steel are not clear.

[0004] The patent with publication number CN115351458B provides a steel for submerged arc welding wire, a wire rod, a submerged arc welding wire and a preparation method thereof. By calcium treatment, the oxygen content in the steel is reduced, and the content of aluminum and titanium oxides in the molten steel is also reduced, thereby improving the Al2O3 and TiOx type water gap nodulation. However, this method ignores the secondary oxidation of molten steel caused by calcium treatment and the nodulation problem of calcium sulfide and calcium titanate generated by calcium treatment in sulfur-containing titanium-containing welding wire steel.

[0005] In the existing disclosed technologies, there is no good method to solve the water gap nodulation problem of small billet sulfur-containing titanium-containing welding wire steel during pouring, and the surface quality and internal quality of the cast billet are often ignored. To solve the above problems, the present application provides a small billet sulfur-containing titanium-containing welding wire steel and its preparation method, which provides technical support for producing sulfur-containing titanium-containing welding wire steel from small billets. SUMMARY

[0006] In order to solve the above problems, the present application discloses a small billet sulfur-containing titanium-containing welding wire steel and its preparation method, and the specific technical scheme is as follows:

[0007] A preparation method of a small billet sulfur-containing titanium-containing welding wire steel, comprising a converter smelting process, a refining process and a continuous casting process, specifically:

[0008] In the converter smelting process, the tapping is deoxidized and alloyed by aluminum block, ferrosilicon and silicon manganese, and the lime is added to pre-slag, and the bottom blowing flow is controlled at 1000~1500NL / min, and after the tapping is finished, the total mass content of FeO and MnO in the slag is controlled to be ≤2.5%;

[0009] In the refining process, lime, carbide and aluminum particles are added for slagging and diffusion deoxidation, and after the end of slagging, the slag basicity is controlled to be 2.5~3.0, the total mass content of FeO and MnO in the slag is ≤0.5%, and the total oxygen content of the molten steel is ≤10ppm, and at 23~27min of refining, 1100~1300m titanium wire is fed above the argon blowing point, and 8~10min apart, and when [S]≤30ppm, 80~100m sulfur wire is fed, and when 30ppm<[S]≤60ppm, 40~80m sulfur wire is fed, and the feeding speed of titanium wire and sulfur wire is controlled at 200~300m / min, and the bottom blowing flow is 100~200NL when feeding the wire;

[0010] In the continuous casting process, the inclusion is controlled to be gathered at the stopper head and the water gap bowl by the stopper shaking method, the basicity of the protective slag is controlled to be between 0.85~0.95, the TiO2 is controlled to be between 3%~4%, the viscosity is controlled to be between 1.0~1.1Pa·S, the inner and outer arc nozzle spacing and the left and right side arc nozzle spacing at the same height of the second cooling zone 1 and 2 are controlled to be between 386±0.2mm, and the inner and outer arc nozzle spacing and the left and right side arc nozzle spacing at the same height of the second cooling zone 3 and 4 are controlled to be between 364±0.2mm.

[0011] Further, in the converter smelting process, the converter tapping volume is 130~140t, and when 30t is tapped, aluminum block, ferrosilicon and silicon manganese are sequentially added for deoxidation and alloying, wherein the aluminum block is 60~80kg, the ferrosilicon is 900~1000kg, and the silicon manganese is 800~900kg, and when 80t is tapped, 300~400kg of lime is added for pre-slagging, and the molten steel is mixed and stirred while the bottom blowing flow is increased for slag-metal stirring.

[0012] Further, in the refining process, the slag composition includes CaO: 59~62%, SiO2: 19~24%, Al2O3: 5~14%, MgO: 4~6%, (FeO+MnO)≤0.5%, and the rest is unavoidable impurities.

[0013] Further, in the refining process, soft stirring is started 15~18min after the titanium wire is fed, and the soft stirring time is 10~12min.

[0014] Further, in the continuous casting process, the continuous casting billet cross section is 140mm×140mm, the continuous casting speed is controlled to be between 2.5~2.6m / min, and the tundish superheat is 45~55℃.

[0015] Further, in the continuous casting process, the tundish adopts a premelted high basicity covering agent with basicity of 6-8, the stopper adopts a shaking stopper method, when the [Ti] loss in the molten steel is ≤200ppm, the shaking amplitude of the stopper increases by 0.2mm, and the shaking frequency is 3 times / s, when the [Ti] loss in the molten steel is >200ppm, the shaking amplitude of the stopper increases by 0.3mm, and the shaking frequency is 5 times / s.

[0016] Further, in the continuous casting process, the composition of the protective slag includes, in mass percentage, SiO2: 34-35%, CaO: 29-33%, MgO: 0.9-1.0%, TiO2: 3-4%, Fe2O3: 1.0-1.1%, Al2O3: 7-8%, F ~ : 3-4%, C: 13-14, moisture ≤0.5%, and the balance is unavoidable impurities.

[0017] A sulfur and titanium-containing welding wire steel prepared by the method.

[0018] Further, the composition of the finished sulfur and titanium-containing welding wire steel includes, in mass percentage, C: 0.055-0.085%, Si: 0.75-0.85%, Mn: 1.44-1.54%, Ti: 0.16-0.21%, Al: 0.008-0.01%, P ≤0.015%, S: 0.006-0.017%, Ca ≤0.0012%, and the balance is Fe and other unavoidable impurities.

[0019] The technical principle of the present application is:

[0020] In the converter tapping process, aluminum blocks, ferrosilicon, silicon manganese and lime are added for deoxidization and alloying and slag making, which not only can control the total oxygen content of the molten steel, but also can reduce the oxidizability of the slag. During tapping, the molten steel is mixed and the bottom blowing flow is increased, the mixing and stirring between the slag and the gold are enhanced, which is beneficial to removing a large amount of non-metallic inclusions through slag washing.

[0021] In the refining process, the total oxygen content in the steel is controlled by increasing the basicity of the slag, and the calcium carbide and aluminum particles are spread on the slag surface for diffusion deoxidization. The sulfur in the steel is inevitably reduced to a low level during the process, so it is necessary to feed sulfur wire in the later stage of refining to meet the composition requirements. Precise control of the wire feeding speed and timing can not only reduce the secondary oxidation of the molten steel, but also ensure sufficient floating time of the inclusions.

[0022] The continuous casting process adopts the stopper shaking technology to control the inclusion gathering in the nozzle bowl and the stopper head, and improves the viscosity of the protective slag to reduce the influence of the stopper shaking on the liquid surface fluctuation, and through improving the basicity and TiO2 content of the protective slag, the reaction between SiO2 in the protective slag and Ti element in the molten steel is inhibited, and the intermediate ladle superheat is beneficial to the melting of the protective slag and the reduction of TiN precipitation, and the distance between the nozzle of the secondary cooling zone and the surface of the casting blank is increased to avoid the surface and center strong cooling, which is beneficial to reducing the generation of intermediate cracks.

[0023] The beneficial effects of the present application are:

[0024] The present application controls the total oxygen content in the steel and reduces the inclusion quantity by optimizing the deoxidizer and deoxidizing slagging mode.

[0025] The present application precisely controls the wire feeding speed and wire feeding timing, reduces the secondary oxidation of molten steel, and ensures sufficient floating time of inclusions.

[0026] The present application adopts the stopper shaking technology to control the inclusion gathering in the stopper head and the nozzle bowl, and avoids causing nozzle clogging.

[0027] The present application optimizes the composition of the protective slag, reduces the influence of the stopper shaking on the liquid surface fluctuation, and inhibits the slag-metal reaction.

[0028] The present application optimizes the position of the secondary cooling nozzle, which is beneficial to the uniform cooling of the casting blank, thereby controlling the intermediate cracks.

[0029] In summary, the present application solves the problems of slag inclusion on the surface of small square billet sulfur and titanium welding wire steel, intermediate cracks and nozzle clogging. DETAILED DESCRIPTION

[0030] The present application will be further illustrated in conjunction with the specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present application and not to limit the scope of the present application.

[0031] The following gives four specific embodiments of the present application, the production method includes converter smelting, LF refining and continuous casting process, and the specific process steps are described as follows:

[0032] In the converter process, aluminum block, silicon iron and silicon manganese are used for deoxidation and alloying during tapping, lime is added for pre-slagging, the bottom blowing flow is controlled at 1000-1500 NL / min, and after the tapping is completed, the content of (FeO+MnO) in the slag is controlled to be less than or equal to 2.5%; the converter tapping amount is 130-140 t, and when 30 t of molten steel is tapped, aluminum block, silicon iron and silicon manganese are sequentially added for deoxidation and alloying, wherein the aluminum block is 60-80 kg, the silicon iron is 900-1000 kg, and the silicon manganese is 800-900 kg; when 80 t of molten steel is tapped, 300-400 kg of lime is added for pre-slagging, and the molten steel is mixed and stirred to increase the bottom blowing flow for slag-metal stirring. The data of specific embodiments 1-4 are as shown in Table 1.

[0033] The converter tapping quantity is 130 t, 60 kg of aluminum block, 900 kg of ferrosilicon, and 800 kg of ferromanganese are added at the time of tapping 30 t to carry out deoxidation and alloying, 300 kg of lime is added at the time of tapping 80 t to carry out pre-slagging, and the slag-steel stirring is carried out by increasing the bottom blowing flow while mixing the molten steel. The bottom blowing flow is controlled at 1000-1500 NL / min during the converter tapping, and the content of (FeO+MnO) in the slag is 2.5% after the tapping is completed.

[0034] Table 1

[0035]

[0036] In the refining process, lime, carbide, and aluminum particles are added to carry out slagging and diffusion deoxidation, the slag basicity is controlled at 2.5-3.0 after the slagging is completed, the content of (FeO+MnO) in the slag is ≤0.5%, and the total oxygen content of the molten steel is ≤10 ppm, the sulfur wire and the titanium wire are accurately fed according to the sulfur and titanium contents of the second refining sample, the wire feeding speed is controlled at 200-300 m / min, and the bottom blowing flow is at 100-200 NL during the wire feeding; the slag composition includes CaO: 59-62%, SiO2: 19-24%, Al2O3: 5-14%, MgO: 4-6%, (FeO+MnO) ≤0.5% by mass %, and the rest is other unavoidable impurities. The soft stirring is started 15-18 min after the titanium wire is fed, and the soft stirring time is 10-12 min. The data of specific embodiments 1-4 are as shown in Table 2.

[0037] Table 2

[0038]

[0039] In the continuous casting process, the stopper shaking technology is used to control the aggregation of inclusions at the stopper head and the water gap bowl, the shaking amplitude increase is 0.2 mm, and the shaking frequency is 3 times / s. The basicity of the protective slag is controlled at 0.85, the TiO2 is controlled at 3%, and the viscosity is controlled at 1.0 Pa·S, the composition of the protective slag includes SiO2: 34%, CaO: 29%, MgO: 1.0%, TiO2: 4%, Fe2O3: 1.1%, Al2O3: 8%, F: 4%, C: 14, moisture is 0.5%, and the rest is unavoidable impurities by mass %. The distance between the inner and outer arc nozzles and the distance between the left and right arc nozzles at the same height of the second and third cooling zones are controlled at 385.8 mm, and the distance between the inner and outer arc nozzles and the distance between the left and right arc nozzles at the same height of the third and fourth cooling zones are controlled at 363.8 mm. ~

[0040] ​In the continuous casting process, the method of stopper shaking is used to control the aggregation of inclusions at the stopper head and the nozzle bowl, the basicity of the mold powder is controlled at 0.85-0.95, TiO2 is controlled at 3%-4%, the viscosity is controlled at 1.0-1.1 Pa·S, the distance between the inner and outer arc nozzles and the left and right arc nozzles at the same height of the secondary cooling zone 1 and 2 is controlled at 386±0.2 mm, and the distance between the inner and outer arc nozzles and the left and right arc nozzles at the same height of the secondary cooling zone 3 and 4 is controlled at 364±0.2 mm. The cross section of the continuous casting billet is 140 mm×140 mm, the continuous casting speed is controlled at 2.5-2.6 m / min, and the overheat degree of the tundish is 45-55 °C.

[0041] The tundish uses high basicity covering agent, and the stopper uses the shaking method. When the [Ti] loss in the molten steel is ≤200 ppm, the increase of the shaking amplitude of the stopper is 0.2 mm, and the shaking frequency is 3 times / s. When the [Ti] loss in the molten steel is >200 ppm, the increase of the shaking amplitude of the stopper is 0.3 mm, and the shaking frequency is 5 times / s. The composition of the mold powder includes, by mass percentage, SiO2: 34-35%, CaO: 29-33%, MgO: 0.9-1.0%, TiO2: 3-4%, Fe2O3: 1.0-1.1%, Al2O3: 7-8%, F~: 3-4%, C: 13-14, moisture ≤0.5%, and the balance is unavoidable impurities. The data of specific examples 1-4 are shown in Table 3.

[0042] Table 3

[0043]

[0044] The properties of the molten steel in the process of preparing the examples 1-4 are described in detail below, and are shown in Table 4.

[0045] Table 4

[0046]

[0047] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless otherwise defined.

[0048] Based on the above ideal embodiments according to the present application, and based on the above description, relevant personnel can make various changes and modifications without deviating from the technical concept of the present application. The technical scope of the present application is not limited to the content of the specification, and must be determined by the scope of the claims.

Claims

1. A method of producing a small square billet sulfur titanium-containing welding wire steel, characterized by, The method comprises a converter smelting process, a refining process and a continuous casting process, and specifically comprises the following steps: In the converter smelting process, aluminum block, ferrosilicon and silicon manganese are used for deoxidization and alloying during tapping, and lime is added for pre-slagging, and the bottom blowing flow is controlled to be 1000-1500 NL / min, and after the tapping is completed, the total mass content of FeO and MnO in the slag is controlled to be ≤2.5 %; In the refining process, lime, carbide and aluminum particles are added for slagging and diffusion deoxidization, and after the slagging is completed, the slag basicity is controlled to be 2.5-3.0, and the slag composition comprises, in percentage by mass, CaO: 59-62 %, SiO2: 19-24 %, Al2O3: 5-14 %, MgO: 4-6 %, (FeO+MnO) ≤0.5 %, and the rest is inevitable impurities; the total oxygen content of the molten steel is ≤10 ppm, and at 23-27 min of the refining, 1100-1300 m titanium wire is fed above the argon blowing point, and after the titanium wire is fed for 15-18 min, soft stirring is started, and the soft stirring time is 10-12 min; 8-10 min is interval, and when [S] ≤30 ppm, 80-100 m sulfur wire is fed, and when 30 ppm<[S] ≤60 ppm, 40-80 m sulfur wire is fed, and the feeding speed of the titanium wire and the sulfur wire is controlled to be 200-300 m / min, and the bottom blowing flow is 100-200 NL during the wire feeding; In the continuous casting process, the inclusion aggregation at the stopper head and the nozzle bowl is controlled by using the stopper shaking method, the tundish is provided with a premelted high-basicity covering agent with a basicity of 6-8, the stopper is provided with a shaking method, when the [Ti] loss in the molten steel is ≤200 ppm, the stopper shaking amplitude increase is 0.2 mm, and the shaking frequency is 3 times / s, when the [Ti] loss in the molten steel is >200 ppm, the stopper shaking amplitude increase is 0.3 mm, and the shaking frequency is 5 times / s; the basicity of the protective slag is controlled to be between 0.85 and 0.95, the TiO2 is controlled to be between 3 % and 4 %, the viscosity is controlled to be between 1.0 and 1.1 Pa·S, the inner and outer arc nozzle spacing and the left and right arc nozzle spacing at the same height of the secondary cooling 1 zone and the secondary cooling 2 zone are controlled to be between 386±0.2 mm, and the inner and outer arc nozzle spacing and the left and right arc nozzle spacing at the same height of the secondary cooling 3 zone and the secondary cooling 4 zone are controlled to be between 364±0.2 mm.

2. A process for the production of small square sulphur and titanium bearing welding wire steel as claimed in claim 1, wherein, In the converter smelting process, the converter tapping amount is 130-140 t, and when 30 t of molten steel is tapped, aluminum block, ferrosilicon and silicon manganese are sequentially added for deoxidization and alloying, wherein the aluminum block is 60-80 kg, the ferrosilicon is 900-1000 kg, and the silicon manganese is 800-900 kg, 300-400 kg of lime is added for pre-slagging when 80 t of molten steel is tapped, and the molten steel is mixed and stirred to increase the bottom blowing flow for slag-metal stirring.

3. A process for the production of small square billet sulphur and titanium bearing welding wire steel as claimed in claim 1, wherein, In the continuous casting process, the continuous casting billet section is 140 mm×140 mm, and the continuous casting speed is controlled to be between 2.5 and 2.6 m / min, and the tundish superheat is 45-55 ℃.

4. A process for the production of small square billet sulphur and titanium bearing welding wire steel as claimed in claim 1, wherein, The composition of the protective slag in the continuous casting process includes, in mass percentage, SiO2: 34-35%, CaO: 29-33%, MgO: 0.9-1.0%, TiO2: 3-4%, Fe2O3: 1.0-1.1%, Al2O3: 7-8%, F ~ : 3-4%, C: 13-14, moisture ≤0.5%, and the balance being unavoidable impurities. 5.A sulfur and titanium-containing welding wire steel prepared by the method for preparing the sulfur and titanium-containing welding wire steel according to any one of claims 1-4.

6. The sulphur and titanium-containing welding wire steel according to claim 5, characterized in that, The finished product composition of the sulfur-containing titanium-containing welding wire steel includes, in mass percent, C: 0.055-0.085%, Si: 0.75-0.85%, Mn: 1.44-1.54%, Ti: 0.16-0.21%, Al: 0.008-0.01%, P≤0.015%, S: 0.006-0.017%, Ca≤0.0012%, the remainder being Fe and other unavoidable impurities.

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