阅读说明：本技术 一种对钢液进行散状物料喂线处理的包芯线产品及其加工方法 (Cored wire product for feeding molten steel with loose materials and processing method thereof ) 是由 乌力平 李国安 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种对钢液进行散状物料喂线处理的包芯线产品及其加工方法,属于冶金技术领域。本发明的产品在加工时通过对已完成散装内芯物料装料和封口的管状容器钢壳局部沿轴向进行连续挤压,并对挤压部位形成凹陷状的钢壳横截面进行减径圆整,使得产品横截面因具有局部凹口而变小,其内部物料填充密实度高、与外壳的接触密度大,内部气体含量少。采用本发明的技术方案可以延长外壳封闭时间,有效抑制气体急剧蒸发,减少镁或/和钙的蒸发和氧化损失,从而提高和稳定采用喂线工艺时钢中合金化或夹杂物改性变质处理元素的收得率,并同时减少喂线(特别是镁或/和钙处理)时对钢液的污染和现场环境的危害。(The invention discloses a cored wire product for feeding molten steel with a loose material and a processing method thereof, belonging to the technical field of metallurgy. When the product is processed, the local part of the steel shell of the tubular container which is filled with the bulk inner core material and sealed is continuously extruded along the axial direction, and the cross section of the steel shell with the concave shape formed at the extrusion part is reduced and rounded, so that the cross section of the product is reduced due to the local notch, the filling compactness of the material in the product is high, the contact density with the shell is high, and the content of gas in the product is low. The technical scheme of the invention can prolong the enclosure closing time, effectively inhibit the rapid evaporation of gas and reduce the evaporation and oxidation loss of magnesium or/and calcium, thereby improving and stabilizing the yield of alloying or inclusion modification treatment elements in steel when a wire feeding process is adopted, and simultaneously reducing the pollution to molten steel and the harm to the field environment when the wire is fed (particularly the magnesium or/and calcium is treated).)

1. The utility model provides a carry out core-spun yarn product that loose form material feed line was handled to molten steel which characterized in that: the material feeding device comprises a shell (110) and a material (210), wherein the shell (110) is processed into a tubular strip-shaped structure, and notches (410) distributed along the length direction of the shell (110) are processed on the surface of the shell; the material (210) is granular and is densely filled in the inner cavity of the shell (110) and used for feeding molten steel.

2. The cored wire product for molten steel bulk material feeding treatment according to claim 1, wherein: the recess (410) includes at least one.

3. A cored wire product for molten steel bulk material feeding treatment according to claim 2, characterized in that: the recess (410) is located at a seal (310) on the housing (110).

4. The cored wire product for molten steel bulk material feeding treatment according to claim 1, wherein: the recess (410) includes two, one at the seal (310) on the housing (110) and the other at the other side of the seal (310).

5. A cored wire product for molten steel subjected to wire feeding treatment of a bulk material according to any one of claims 1 to 4, wherein: the shell (110) is made of a low-carbon steel strip, and the thickness range of the low-carbon steel strip is 0.3-1.2 mm.

6. A cored wire product for molten steel subjected to wire feeding treatment of a bulk material according to any one of claims 1 to 4, wherein: the housing (110) comprises a double structure with a recess (410) at the closure (310) of the housing (110).

7. A method of manufacturing a cored wire product by feeding molten steel with a strand of a bulk material according to any one of claims 1 to 6, wherein: the method comprises the following operation steps:

step one, manufacturing a shell (110) into a groove container with a U-shaped cross section, and distributing materials (210);

step two, closing the upper end opening of the shell (110) and processing the shell into a closed tubular structure with a seal (310), wherein the diameter of the closed tubular structure is recorded as D₀；

Step three, setting a proper length distance from the closed sealing position to start extrusion processing, carrying out local continuous extrusion and diameter reduction rounding on the tubular structural body obtained after the sealing in the step two is finished along the longitudinal direction or the axial direction, forming longitudinally distributed notches (410) on the treated shell (110), recording the diameter of the treated tubular structural body as D, wherein D is less than D₀。

8. The method for processing a cored wire product for molten steel bulk material feeding treatment according to claim 7, characterized in that: in the third step, the distance from the closed sealing point to the extrusion processing starting point is controlled to be more than 10 times of the diameter of the core-spun yarn product.

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to a cored wire product for feeding molten steel by adopting bulk materials (reactive type or non-reactive type), and a processing method and a using method thereof, aiming at improving the quasi-bulk density of the bulk materials in an inner cavity, reducing residual air in the inner cavity, promoting the heat absorption of the internal materials, prolonging the melting time of a shell and promoting the reaction of the reactive materials.

Background

The method for feeding the molten steel through the cored wire is a method for adding the inner core material in the refining process (particularly in the final stage of refining) widely adopted in the molten steel refining process, can avoid the adverse effect of the top slag of the steel ladle on feeding, can directly add the material into the deep part of the molten steel, and increases the yield of the molten steel on the material. The core-spun yarn is characterized in that materials wrapped inside the core-spun yarn comprise an integral solid round bar material (such as a pure calcium bar and the like), more fine powder bulk materials with different particle sizes are provided, the bulk materials are non-reactive materials (such as carbon powder and the like) only subjected to alloying, and reactive materials (such as direct reduction alloying powder, silicon calcium powder for inclusion modification and the like) subjected to real-time chemical reaction after being fed into molten steel are also provided, so that the core-spun yarn is convenient to feed when being coiled and refined, the core-spun yarn is preformed according to a circular cross section and is sealed and locked after being gravity fed, and certain internal material looseness can occur according to the types and particle sizes of the materials. The existing bulk material core-spun yarn has loose and not compact internal materials, and has the following problems in the use and transportation process:

1. because the accurate density of the internal material of the cored wire is not high, the contact between the material and the shell and between the material and the material is not tight, so that the heat transfer resistance of the molten steel from the shell to the material and the material is large, the shell is heated up quickly and melted early relatively, the isolation of the internal material relative to the molten steel is not facilitated, and the thicker cored wire shell needs to be consumed to a certain extent.

2. For reactive bulk materials, it is often desirable to stimulate and drive real-time chemical reactions by the heat energy of the molten steel, and it is also more desirable that the steel shell be able to melt and fracture as late as possible to allow internal chemical or physicochemical reactions to proceed more fully. However, the loose materials cause large heat transfer thermal resistance, which is not beneficial to the excitation and reaction of chemical reaction and the sealing of reaction, and can generate adverse effect on the wire feeding treatment of molten steel.

3. The wire feeding treatment is generally the last link of the molten steel refining process. The core-spun yarn has loose and non-compact internal materials, namely the capacity of internal air is large, no matter oxygen and nitrogen in the air react with elements in the steel or are dissolved in the steel in the core-spun yarn or after entering the steel liquid, certain pollution can be formed on the steel liquid, and especially the negative influence on ultra-pure steel is large.

4. The cored wire has loose materials and large air capacity, and can suddenly expand several times to form large bubbles and float upwards to escape after being suddenly heated, so that molten steel in a ladle is violently overturned and seriously exposed, the loss of aluminum in relative steel is large, nitrogen is seriously increased, and the molten steel is polluted. Meanwhile, when calcium, magnesium or magnesium-calcium treatment is carried out, 1) calcium or/and magnesium high vapor pressure elements easily enter air bubbles and are combined into oxides by oxygen in the air to be directly oxidized and lost; 2) calcium or/and magnesium vapor enters the bubbles to reduce partial pressure and reduce dissolution to molten steel; 3) calcium or/and magnesium vapor enters the bubbles to enlarge the bubbles, the floating speed is accelerated, and the loss is caused when large bubbles float upwards and overflow the molten steel; 4) the combination and superposition of the air bubbles and the calcium-magnesium steam can cause severe turnover and severe exposure of the molten steel in the treatment process, and can also cause extra temperature loss of the molten steel in the treatment process, even molten steel overflow, severe pollution of the field operation environment and overflow loss of the molten steel.

5. The inside material of covering wire is loose, not closely knit, can make to found the inside material granule of rolling up the covering wire of transportation and storage to fall and slide because vibration etc. appear in commodity circulation in-process such as transportation of rolling up, produces the macrosegregation of material matter kind and particle diameter in the covering wire etc. has negative effects to the reaction process and the abundant degree of reaction type material.

6. The inside material of cored wire is loose again, not closely knit, can make to roll up the inside material granule of transportation and the cored wire of storage immediately and gather because the serious gravity landing of production inside material such as vibration etc. produces in commodity circulation processes such as transportation for the line is rolled up and is surpassed the position and appear periodic dead space, and the smooth and easy of the operation of feeding the line is influenced because of pinch roller pressure collapses when feeding the line and handle, especially can also appear the condition that the line caused the interrupt in the operation to thin shell cored wire even.

Because the existing core-spun yarn made of bulk materials has the problems, especially for the conditions of reactive materials and thin shells, the composition yield of molten steel wire feeding treatment is low, the fluctuation is large, the molten steel pollution is serious, the field environment is dirty and messy, and the process state and the final result are not ideal.

Through search, the Chinese patent application numbers are: 201110078560.5, filing date: 3, 29 months in 2011, the name of the invention is: cored wire and method for preparing the same. The cored wire disclosed in the application comprises a sheath and a core material, wherein the core material is tightly filled in the sheath, the sheath comprises an outer steel sheet layer and an inner metal layer, the two sides of the sheath are inwards turned at a sheath interface and are extruded and fixed, the melting point of the metal layer is smaller than steel, the thickness of the metal layer is 0.2mm, and the thickness of the steel sheet layer is 0.2 mm. The core-spun yarn is claimed to be capable of compactly filling the core material in the sheath, and researches show that the core-spun yarn tightly filled in the sheath cannot be obtained by the production method for sealing provided by the application due to the compression and slippage of the material, and the problems still occur when the core-spun yarn is used for feeding molten steel, so that the yield and the fluctuation of alloying elements are finally high, the pollution of the molten steel is serious, and the pollution of the field environment is poor.

Disclosure of Invention

1. Problems to be solved

Aiming at the problems of loose and non-compact materials and much residual air in the prior bulk material cored wire for molten steel wire feeding treatment, the invention provides a cored wire product for performing the bulk material wire feeding treatment on molten steel and a processing method thereof. The technical scheme of the invention can prolong the closing time of the shell in the molten steel, effectively inhibit the rapid evaporation of gas, and reduce the evaporation and oxidation loss of magnesium or/and calcium, thereby improving and stabilizing the yield of alloying or inclusion modification treatment elements in the steel when the wire feeding process is adopted, and simultaneously reducing the pollution to the molten steel and the harm to the field environment when the wire is fed (particularly the magnesium or/and calcium is treated).

2. Technical scheme

In order to solve the problems, the technical scheme adopted by the invention is as follows:

the invention relates to a cored wire product for carrying out wire feeding treatment on molten steel in a bulk state, which comprises a shell and materials, wherein the shell is processed into a tubular strip-shaped structure, and notches distributed along the length direction of the shell are processed on the surface of the shell; the material is powdery and is densely filled in the inner cavity of the shell and used for feeding molten steel.

Further, the recess includes at least one.

Further, the recess is located at a seal on the housing.

Further, the recess includes two, one at the seal on the housing and the other at the opposite side of the seal.

Furthermore, the shell is made of low-carbon steel materials, and the total thickness of the shell ranges from 0.3mm to 1.2 mm.

Further, the housing includes a double-layered structure with a recess at a seal of the housing.

The invention relates to a processing method of a cored wire product for carrying out bulk material wire feeding treatment on molten steel, which comprises the following operation steps:

step one, manufacturing a shell into a groove container with a U-shaped cross section, and distributing materials;

step two, closing the upper end opening of the shell, and processing the shell into a closed tubular structure with a seal, wherein the diameter of the closed tubular structure is marked as D₀；

Step three, setting a proper length distance from the closed sealing to start extrusion processing, carrying out local continuous extrusion and diameter reduction rounding on the tubular structural body obtained in the step two along the longitudinal direction or the axial direction, forming longitudinally distributed notches on the treated shell, recording the diameter of the treated tubular structural body as D, wherein D is less than D₀。

Further, in step three, the length distance from the point of closing the seal to the point of starting the extrusion process is controlled to be larger than the diameter of the core-spun yarn (the diameter of the product without extrusion, diameter reduction and rounding, i.e., D)₀) 10 times higher than the original value.

Drawings

FIG. 1 is a schematic cross-sectional view of a cored wire product after sealing (without longitudinal or axial continuous extrusion and diameter reduction rounding of the product);

FIG. 2 is a schematic cross-sectional view of the core-spun yarn product after longitudinal or axial continuous extrusion and diameter reduction rounding treatment;

fig. 3 is a schematic cross-sectional view of the core-spun yarn product with a double-layer sheath according to the present invention (in the production process, the partial continuous extrusion and diameter reduction and rounding treatment along the longitudinal or axial direction are completed).

In the figure:

110. a housing; 210. material preparation; 310. sealing; 410. a recess.

Detailed Description

As shown in fig. 1 to 3, the cored wire product for performing the wire feeding treatment on the molten steel in a bulk state comprises a shell 110 and a material 210, wherein the shell 110 is processed into a tubular strip-shaped structure, the shell 110 is made of a low-carbon steel material and can be designed into a single-layer or double-layer structure, and as shown in fig. 3, when the shell is double-layer, a locally continuous extrusion concave position of an outer-layer steel shell is arranged at a butt joint closed position of an inner-layer steel shell. The total thickness of the sheath material is 0.3-1.2mm, and it should be noted that, in order to facilitate the production of the core-spun yarn product, when the sheath 110 is of a single-layer structure, the thickness is relatively difficult to control when the thickness is more than 1.0mm, and generally can be 0.3-0.8 mm. The materials 210 are mainly bulk materials for steelmaking, including alloying materials, bulk steelmaking auxiliary materials and the like, and are not limited specifically, such as common carbon powder, calcium silicate powder and the like, then the materials 210 are made into fine particles, and are densely filled in the inner cavity of the shell 110, sealing is firstly completed, then the extrusion processing is started to be performed on the cored wire shell 110 at a fixed point according to a length distance which is ten times larger than the diameter of the cored wire product, and after a notch (410) is formed, rounding is performed, and the cored wire product with a reduced cross section is processed to be used for feeding molten steel.

Specifically, the quasi-density of the bulk materials in all the core-spun yarn products on the market is not high, the contact between the materials and the shell and between the materials is not tight, and the main reason for the situation is the structure and the processing characteristics of the core-spun yarn, and the core-spun yarn is locally extruded at the sealing position when the sealing is generally carried out, but the bulk materials are easy to slide and overflow from the side to be sealed due to extrusion and can not be compacted. The processing method of the product of the invention mainly comprises the following steps:

step one, manufacturing the shell 110 into a groove container with a U-shaped cross section by adopting the existing production equipment, and distributing materials 210;

step two, after the material distribution is completed, the upper end opening of the shell 110 is closed by using the existing production equipment, and the tubular structure with the seal 310 is processed, as shown in fig. 1, the diameter (i.e. the diameter of the circular cross section) of the processed tubular structure is marked as D₀；

Step three, starting extrusion processing by setting a proper length distance l from the closed sealing position, locally and continuously extruding, reducing and rounding the tubular structural body obtained in the step two along the longitudinal direction or the axial direction, forming longitudinally distributed notches 410 on the processed shell 110, recording the diameter (namely the diameter of the circular cross section of the tubular structural body as shown in fig. 2) of the processed tubular structural body as D, wherein D is less than D₀。

It should be noted that, in the third step, the length distance l from the point of closing the seal to the start of extrusion processing is particularly important for the filling compactness of the material 210, and when the length is too short, the material 210 slides and overflows at the processing position of the seal 310 in the extrusion process, so that it cannot be guaranteed that the material 210 in the cavity of the core-spun yarn shell 110 is extruded tightly; the processing length is too long, so that the existing core-spun yarn processing equipment is greatly changed, the equipment size is large, the occupied area is large, and the production cost is high. The invention optimizes the processing method, especially the processing length l, and controls l to be more than 10D₀During the time, can effectively make material 210 in the extruded instant too late to transmit pressure and take place mutual slip and spill over from sealing the position to can effectively guarantee material 210's the closely knit degree of packing, and then solve the problem of current cored wire in transportation and use. Meanwhile, as shown in FIG. 2 or FIG. 3, the surface of the product of the present invention has a longitudinal concave portionThe shape of the notch 410 is maintained after reducing and rounding, and the number of the notches 410 at least comprises one. When one recess 410 is provided, it may be located at the seal 310 of the housing 110 or at other locations on the housing 110. When the number of the recesses 410 is two (not shown), one of the recesses 410 may be provided at the seal 310 on the housing 110 and one may be provided at the other side of the seal 310. The optimization of the number and the position distribution of the notches 410 can further improve the filling compactness of the material 210 and ensure the use effect of the cored wire product of the invention. When a double skin is used, a single notch 410 is used, preferably located at the seal 310 of the skin 110, to ensure that the seal is intact and to reduce the power of the compression device.

In addition, the volume of the inner cavity reduced after the product is extruded and rounded is the volume of the air to be extruded, and the increase of the quasi-density of the internal material corresponds to the reduced volume of the inner cavity. The cross section of the inner cavity of the product shell 110 after the diameter reduction and rounding treatment is smaller than that before the continuous extrusion treatment. The roundness of the cross section of the cored wire is still kept due to rounding after local extrusion and out-of-round, and no negative influence is caused on winding and wire feeding in the production process of products. More optimally, when the cored wire product is deformed by external force during coiling or feeding, the extrusion groove (namely the notch 410) can elastically deform to a certain degree to enlarge the cross section area of the wire, so that the tension on the longitudinal sealing position of the cored wire generated during deformation can be released, and the sealing can not crack.

Compared with the existing cored wire, the cored wire product can compactly fill the bulk material 210 in the shell 110, and can reduce the cross section area of the shell and the volume of the total inner cavity to a certain extent, so that air remained in partial inner gaps is discharged, the collection compactness of the material is increased, the contact and combination tightness between the material and between the material and the shell are improved, the heat transfer of molten steel heat from the shell to the material and the material is facilitated, the macro segregation of the material types and the particle sizes of the inner materials is eliminated, and the problems of periodic empty sections and the like of the inner materials of a cored wire coil are avoided.

Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:

1) during molten steel wire feeding treatment, heat is transferred to internal materials and materials from the shell, so that the melting time of the shell is prolonged;

2) the reaction type materials needing to be excited by heat transmitted by molten steel promote the internal reaction process and the full degree;

3) the corresponding pollution of oxygen, nitrogen and the like in the discharged redundant air to the molten steel is reduced;

4) the molten steel pollution and metal splashing caused by the turnover of the liquid level of the steel ladle due to the violent expansion of the residual gas in the process of treatment are reduced;

5) the influence of partial pressure reduction of magnesium and calcium vapor caused by air on the dissolution of molten steel and the overflow of magnesium and calcium caused by the appearance of large bubbles during magnesium and calcium treatment are reduced;

6) the consumption of oxygen in the residual air to the reducing agent in the reactive material is reduced;

7) the macrosegregation of the material types and the grain diameters in the core-spun yarns caused by vibration and the like in the material flow process of the reaction type core-spun yarns is eliminated, and the negative influence on the internal reaction caused by the nonuniform reactants is basically avoided;

8) the problems that the core-spun yarn roll is generated due to more pores, the serious gravity accumulation of internal materials in the core-spun yarn roll logistics process causes periodic empty sections and the like to influence the smoothness of the yarn feeding operation are solved.

The invention is further described with reference to specific examples.

Example 1

In this example, a cored wire having a diameter of 13mm was produced. When the notch 410 is pressed, the distance l from the pressing point to the sealing point is set to 145mm (about l: 11D)₀). Taking 10.0m finished core-spun yarn, dividing the finished core-spun yarn into five sections, each section is 2.0m, weighing core materials in each section, simultaneously measuring the diameter (outer diameter) of each section and converting the equivalent diameter, and obtaining the result:

comparative example 1

This comparative example uses substantially the same core wire size and raw material as in example 1, and is processed substantially in the same manner as in example 1, except that the diameter reduction by extrusion is directly performed as in example 1. After a core-spun yarn product is prepared, 20.0m of finished core-spun yarn is uniformly divided into ten sections of 2.0m, and the weighing result of bulk materials in each section is as follows:

example 2

In this example, a cored wire having a diameter of 13mm was produced. When the notch 410 is pressed, the distance l from the pressing point to the sealing point is set to 145mm (about l: 11D)₀). Taking 20.0m finished core-spun yarn, uniformly dividing the finished core-spun yarn into ten sections of 2.0m, and weighing the bulk materials in each section as follows:

numbering	1	2	3	4	5	6	7	8	9	10	Average	Standard deviation of
													Weight (g)	179	181	181	180	181	179	179	180	180	181	180.1	0.876

Comparative example 2-1

The comparative example uses the core-spun yarn and raw material which are basically the same as those of the example 1, and the processing method is basically the same as the example 1, and is different from the processing method of the example 1 in that the extrusion and the diameter reduction are directly and synchronously carried out during the sealing. After a core-spun yarn product is prepared, 20.0m of finished core-spun yarn is uniformly divided into ten sections of 2.0m, and the weighing result of bulk materials in each section is as follows:

numbering	1	2	3	4	5	6	7	8	9	10	Average	Standard deviation of
													Weight (g)	171	171	169	165	170	171	169	166	167	170	169.5	2.183

Comparative examples 2 to 2

This comparative example, which employed substantially the same core wire size and material as in example 1 and was processed substantially in the same manner as in example 1, was different from the processing method of example 1 in that the extrusion device was moved in the direction of the sealing point during extrusion of the notch 410 so that the distance l from the extrusion point to the sealing point was 90mm (about l to 7D)₀). After the core-spun yarn product is prepared, 20.0m of finished core-spun yarn is uniformly divided into ten sections of 2.0m, and the weighing result of bulk materials in each section is as follows:

numbering	1	2	3	4	5	6	7	8	9	10	Average	Standard deviation of
													Weight (g)	176	180	177	179	176	179	177	178	176	178	177.5	1.430

Example 3

In this embodiment, calcium treatment is performed on molten steel, calcium powder with calcium and silicon contents of 30% and 55% respectively is used to prepare a cored wire with an outer diameter of 10mm, the granularity of a core material is not more than 1.5mm, and a low-carbon steel strip of a shell of the cored wire is a single-layer and has a thickness of 0.55 mm.

The processing method of the invention is adopted to manufacture the cored wire, and the cored wire is locally pressed down and rounded along the axial direction by adopting the roller after being packaged, and a concave groove is formed at the pressed position of the shell. The core-spun yarn is fed into a ladle with the molten steel amount of 130 tons at the speed of 1.8m/sec in the later refining stage of the ladle furnace, the yarn feeding process is basically stable, and the phenomena of molten steel overturning and ladle top slag inclusion are not obvious. After the steel ladle is blown with argon and stirred weakly, calcium is increased by 18ppm in the final molten steel, the yield of the calcium is 31.5 percent, and the acid-soluble aluminum in the steel is lost by 6 ppm.

Comparative example 3

In the comparative example 1, molten steel is added under almost the same conditions and modes as those of the core-spun yarn in the example 1 in the specification and the raw materials (only pressurization and diameter reduction are not performed) and the molten steel is overturned relatively seriously in the yarn feeding process, so that the phenomenon of ladle top slag inclusion is obviously caused, the yield of final calcium after refining is 27.3%, and the loss of acid-soluble aluminum in steel is 8 ppm.

Example 4

In this embodiment, the carbon content of the molten steel is finely adjusted, and the cored wire with the outer diameter of 13mm is manufactured by using carbon powder with the purity of 99%, the granularity of the carbon powder is not more than 1.0mm, the cored wire low-carbon steel strip is a single-layer, and the thickness of the cored wire low-carbon steel strip is 0.3 mm. The core-spun yarn is fed into a ladle with the molten steel amount of 130 tons at the speed of 2.0m/sec in the later refining stage of the ladle furnace, the yarn feeding process is basically stable, the phenomena of molten steel overturning and ladle top slag inclusion are not obvious, the recarburization is accurate, and the carbon yield is 100%.

Comparative example 4

In the comparative example 3, molten steel is added under almost the same conditions and modes as those of the core-spun yarn in the example 2 in the specification and the raw materials (only pressurization and diameter reduction are not performed), the molten steel at the feeding point is overturned in the yarn feeding process, the bright ring phenomenon that the top slag of the steel ladle is pushed away exists, the recarburization is accurate, and the carbon yield is 98.5%.

Example 5

In this example, magnesium-calcium composite treatment was performed. The internal material is a reaction type, and the core-spun yarn with the outer diameter of 10mm is prepared by fully and uniformly mixing magnesium oxide (MgO) with the purity of 90%, calcium, silicon calcium powder with the silicon content of 30% and 55% respectively and aluminum powder with the aluminum content of 99% according to the proportion. The granularity of each material in the core material is not more than 1.5mm, the thickness of the inner layer low-carbon steel band of the core-spun yarn is 0.55mm, the thickness of the outer layer steel band is 0.45mm, the core-spun yarn is manufactured by adopting the processing technology of the invention, and a concave groove is formed and rounded by pressurizing the folding seal of the outer layer steel band at the butt joint of the inner layer steel band when the core-spun yarn is manufactured. The core-spun yarn is fed into a ladle with the molten steel amount of 130 tons at the speed of 1.2m/sec in the later refining stage of the ladle furnace, the yarn feeding process is basically stable, and the phenomena of molten steel overturning and ladle top slag inclusion are not obvious. After the steel ladle argon blowing weak stirring, the increment of magnesium and calcium in the final molten steel is respectively 16 ppm and 14ppm, the yield of the magnesium and the calcium is 34.7 percent and 32.4 percent, the acid-soluble aluminum in the steel is increased by 8ppm in the treatment process, the influence of 17ppm of aluminum increased by the reaction excess aluminum, which is considered according to 70 percent, in the magnesium treatment process is removed, and the acid-soluble aluminum net loss is 7ppm in the actual treatment process.

Comparative example 5

This comparative example 4 used the same core wire gauge, raw material and double shell cored wire structure as in example 3, and molten steel was added in almost the same conditions and manner without performing local pressurization reducing. The phenomena of molten steel turnover and ladle top slag inclusion are obvious in the wire feeding process. After the steel ladle argon blowing weak stirring, the increment of magnesium and calcium in the final molten steel is 14ppm and 13ppm respectively, the yield of the magnesium and the calcium is 27.1 percent and 30.7 percent, and the net loss of acid-soluble aluminum in the steel is 10ppm in the treatment process).